Homemade VHF Sergey Vitsan. VHF receiver in the housing of the radio designer "Yunost" - Homemade - Receivers, components and blocks. Efficient portable radio antenna

Comments (28):

#1 Filyuk Victor October 31 2014

Hello. As far as I understand, the reception frequency of the device lies within the VHF “our range”. How do you need to change the coil data so that you can cover the entire FM range??? .Thank you.

#2 root October 31 2014

For the FM range, you will need to reduce the number of turns of inductor L1. The value of the number of turns is selected experimentally; also, expanding/decreasing the distance between the turns of the coil affects the operating frequency of the L1C2 circuit.

For the range 65.8-73 (MHz) the transistor must be P416 with the letter B or another higher frequency one.
For the 88-108 (MHz) range, you need a higher frequency transistor than the P416B. For the new range, you can try using GT308B-G (threshold 120 MHz), as well as KT361 with any letter (threshold 250 MHz) or KT3107 (threshold 200 MHz).

#3 V. Borovkov December 01 2014

Hello! I’m somehow not sure that even regeneration noise, a useful signal, will be heard in headphones (phones), the noise is very small. Did you make such a receiver yourself and did it work for you?? At least I’m not sure, but I wonder if it’s possible that it will work as written...

P416 p-n-p, and KT603 n-p-n.. be careful when giving beginners analogs.. or you need to specify Kt603 to change the polarity..*** just for fun I collected.. a couple of stations work near Kyiv...

#5 root December 25 2014

March, thanks for the note. The mention of KT603 was removed from the article so as not to confuse newcomers. Now there are quite a lot of high-frequency transistors that can replace the old germanium P416.

I don’t think that the P416 is no longer there; there are still many in storage, from P401 to 416*422, old GT308, etc. But germanium generally works better. (I’ll send it to whoever needs it..)

#7 root December 26 2014

Yes, there are still such transistors at flea markets; I recently bought several GT308s for pennies - the sellers were surprised that someone still needed these rarities))
Germanium transistors do have some advantages over silicon ones. In the article Tube-transistor ULF for headphones there is a plate that compares the physical properties of silicon and germanium.
Let me give you a brief summary advantages of germanium over silicon:

the density is more than 2 times higher;
the mobility of electrons and holes is approximately 3 times higher;
The lifespan of an electron is 2 times higher.

For radio receiving and sound reproducing equipment, germanium can prove to be very interesting! In addition, germanium transistors can be used to assemble very economical designs, for example:

Economical radios with low voltage power supply (0.3-0.7V) from an earth battery;

Therefore, in this design, a VHF receiver on one transistor will also be a plus using germanium transistor.

#8 Clide January 07 2015

Hello, I'm a beginner in this business. Please write to the account of capacitors C1 and C3 what units of measurement are there, and how important is the capacitance indicated in the diagram

#9 root January 08 2015

Capacitor C1 = 12 pF (picoFarad) - here you can allow some deviation, most likely the capacitance of the capacitor within 10-15 pF will not affect the operation.
Capacitor C3 = 36 pF (picoFarad) - in this circuit a minimum deviation is desirable, you can try 30-40 pF.

Also, any capacitance, if the exact value is not available, can be added up from several capacitors by connecting them in parallel - in this case, the capacitance of all capacitors is summed up.
Example: you need a 36pF capacitor - we connect two capacitors 10pF and 25pF in parallel, you get 35pF, which is quite suitable for installation in a circuit.

#10 Clide January 16 2015

Hello again. Thank you very much for your help, thanks to you I assembled my first receiver!
Ps: Picks up FM lightly :)

The P416B transistor can be replaced with a GT308A or other high-frequency N-P-N structure. Here we go again... not N-P-N but P-N-P.

#12 root January 16 2015

When I was editing the article I made a mistake due to carelessness. Why am I so attached to N-P-N, it seems to be due to close communication with the circuits on the KT315)) Corrected! Thank you, March.

Clide, this is great! If you don't mind, write down what parts you changed and what headphones you used.

#13 Clide January 16 2015

Transistor p422 c1 and c3 30pf each C2 - KPE with an air gap, L1 11mm (by the way, this is clearly a AA battery) 10 turns with a cross section of 0.4mm. The headphone output from the player is through a 500-1000 Ohm resistor, and also in parallel with the 500 Ohm resistor through a capacitor I put the outputs on the UHF amplifier
Since the transistor is quite weak, I’m afraid to burn it with my lack of theoretical knowledge

#14 Clide January 28 2015

I need help again, in general I added one amplifying stage on a compound transistor, the receiver became louder, everything seemed to be as it should, but when I increased the power from 2.5V to 5V it began to work the other way around, namely to create very strong interference, completely jamming TV, and the receiver function almost completely disappears. Tell me at least approximately why this could happen.

Here is a complete diagram of this enemy of neighbors.
And yes, I still burned the old transistor, accidentally)

#15 root January 29 2015

Quite a working solution. The circuit becomes a transmitter because you gave the KT603 transistor a lot of current - try replacing the 100 Ohm resistor with a 2-5 kOhm variable resistor and experiment, also try reducing the capacitance of the input capacitor by 10 µF to 0.47 - 1 µF or less. The values to change are highlighted in red on your diagram.

In the article Scheme of a VHF (FM) super-regenerator with two transistors there is a similar solution; you can try connecting the amplifier in the same way only with a compound transistor.

Here are some diagrams and articles from which you can take ideas and knowledge on simple homemade FM radio receivers using transistors:

A simple regenerative VHF-FM receiver using four transistors
Super-generative transistor VHF receivers with low-voltage power supply (1.5V)
Transistor VHF (FM) receivers with ring stereo decoder

#16 Clide January 29 2015

Yes, the 100 ohm resistor was indeed to blame for the interference. I temporarily installed a variable one and installed a 1 µF capacitor. I got rid of the interference, but unfortunately, for some reason, the receiver still refuses to work normally at 5 volts, namely, the sound is very distorted, and excessive sensitivity appears, where you have to turn it micron by micron, and you can’t move. In general, I think that this is some kind of feature of the transistor, I’ll look for another one, I’ll try, if it doesn’t work, I’ll reduce the voltage and that’s it, or I’ll assemble it using a different circuit

#17 root January 29 2015

Connect the 5V power supply and try installing a 200-300 kOhm variable resistor instead of R1, rotating the knob and see how the operation of the receiver changes.

In the amplifier circuit, replace the 280 Ohm resistor with 2-3 kOhm, and select the operating mode with the 52 kOhm resistor you have in the circuit.

Try installing a GT313 or GT311 transistor. They have a cutoff frequency of about 400 MHz. The first p-n-p structure is the same as P416, P422. Second n-p-n, the power polarity changes. GT313 can be found in SCM blocks or VHF blocks of Soviet radio receivers such as Okaen, etc.

#19 Sergey October 10 2018

What resistance p1 am I just not seeing?

#20 root October 10 2018

Sergey, the resistance of resistor R1 is 330 kOhm (330,000 Ohm).

#21 Alexander Compromister October 11 2018

I have a question, suggestion and comment: firstly, why does resistor R1 have a relatively high power of 0.5 W instead of the common power of 0.125 W (see Zakharov-Sapozhnikov diagram)? - In this regard, coil L1 can be wound directly on resistor R1 (but you need to select the number of its turns). - This is secondly, and thirdly, a note: according to the ESKD rules, the power switch is drawn in the opposite direction, i.e. not from the power source, but from the load.

#22 root October 12 2018

The diagram has been redrawn. Resistor R1 is low-power, can be set to 0.125 W or any other power. Coil L1 is frameless.

#23 Kostya May 06 2019

Hello. I am doing a coursework according to your scheme. Help with choosing a speaker. I connected the speaker, but it doesn't even hiss. More details if possible!

#24 root May 06 2019

Hello. You cannot directly connect 4-8 ohm speakers or 16-50 ohm headphones to this circuit. If you do this, the transistor will fail. The circuit is designed to connect phones with a resistance of 1600-2200 Ohms. To use such speakers and headphones, you need to connect a matching transformer.

A miniature matching transformer can be removed from an old radio receiver or made yourself.

You need to connect it to the circuit with winding I with a resistance of more than 1 kOhm, and to the speaker or headphones with winding II, with a resistance of several tens of Ohms.

#25 Alexander Compromister May 07 2019

Is a transformer from a subscriber loudspeaker suitable?

#26 root May 08 2019

Alexander, it will do, but the playback volume will be lower than using a transformer removed from a portable radio.

#27 Alexander Compromister May 08 2019

Is it possible to use mode D of the output transistor in this case and increase the voltage? - What value of sampling frequency should I choose in this case? - Yes, obviously fd>=2fв, but what should we take equal to fв?

#28 Seawar May 08 2019

This is an analog circuit. The output transistor simultaneously acts as an input transistor - as a local oscillator, as a switch, as an AMP, and as a VLF. You can (and optimally) connect the additional ULF, and select which mode you want - on the right hand side.

The all-wave receiver is very good. You press a key, and the multilingual chatter of the planet immediately bursts into the room. You are aware of all the events of the day.

But this receiver has one drawback. Atmospheric and industrial interference sometimes distort music broadcasts so much that it is better to turn off the radio. We offer a way out of this situation. Build a VHF receiver and your room will be filled with pure music, never interrupted by interference.

Schematic diagrams of high-frequency receiver units are shown in Figures 1 and 3.

Figure 1 shows a diagram of the VHF unit and broadband input circuits: a coupling coil with antenna L1 and an oscillating circuit formed by coil L2 and capacitors C1-C2. The received high-frequency signal from the radio station from the circuit is fed to a high-frequency amplifier (UHF), assembled on triode T1. The transistor is connected according to a common base circuit and ensures stable operation of the cascade at VHF frequencies in the 65.8-73.0 MHz range).

The collector circuit of triode T1 includes a selective oscillatory circuit L4-C4-C5-C6. The circuit is adjusted smoothly within the operating range using a variable capacitor C4.

From the UHF circuit the signal is supplied to the emitter of transistor T2. It acts as a high frequency converter.

The heterodyne is assembled according to a circuit with inductive-capacitive coupling. Just like the UHF cascade, it contains a tunable circuit L4-C13-C14-C16, which is continuously tuned using a variable capacitor. The intermediate frequency is 10.7 MHz.

The mixing part of the converter is made according to a standard design. The signals from the local oscillator and the received radio station are supplied to the emitter of transistor T2.

Its collector circuit includes a load - a bandpass filter L5-C15, tuned to an intermediate frequency.

The required DC modes of transistors T1 and T2 are provided by the base bias voltage. It is selected by resistors R3 and R6 included in the divider circuit.

Figure 3 is a schematic diagram of a three-stage intermediate frequency amplifier and frequency detector, made on triodes T3, T4, T5 and diodes D1 and D2. Individual stages of the amplifier are loaded onto filters L7-C20; L9-C24; L11-C36, which are tuned to an intermediate frequency of 10.7 MHz (capacitance C20 and C24 are 160 each, C29-150, and C30 -300 pcf). Communication between the stages is carried out using coils L8, L10, L12, inductively coupled to the loop ones.

The required modes of the DC intermediate frequency amplifier transistors are determined by resistors R9, R15, R21 included in the voltage dividers.

The amplifier is connected through coil L6 to the high-frequency part of the receiver circuit.

There are few homemade parts - these are contour coils and boards. Any resistors and capacitors are suitable for the receiver. True, before purchasing them, you need to clarify what the receiver will be like. If desktop, then you can use ordinary parts, if portable, then small-sized: resistors such as ULM, VS-0.125, capacitors such as KT-1a, KLS, K10-7V, EM, K-50-6, etc.

A dual block of variable capacitors C4-C13 with a maximum capacity of 20-30 pF can be selected either ready-made or converted from some block for transistor receivers by removing the required number of rotor and stator plates.

If only one VHF radio station is received in your area, the unit can be replaced with separate tuning ceramic capacitors of the KPK-M type, and the receiver setting can be made fixed. Make frames for contour coils from plexiglass or polystyrene. Of course, you can also choose ready-made, factory-made ones (see Fig. 2).

Coil L1 of the input circuit contains 5 turns, and L2 - 6 turns of PEL or PEV wire 0.15-0.18. Coil L3 of the UHF circuit contains 11 turns of copper wire without insulation 0.4-0.51 mm. Winding L1 and L2 turn to turn, and L3 with a pitch of 1 mm.

Wind the high-frequency choke coil Dr in a row on the ceramic base of a resistor type BC-0.125. The winding consists of 25 turns of PEL or PEV wire 0.12-0.15. The coil leads are soldered directly to the resistor leads. The heterodyne coil L4 is wound in 1 mm increments with the same wire as L3. It should contain 8 turns with a tap from the 3rd turn, counting from the side of the output connected to the positive bus. High frequency coils with carbonyl iron tuning cores. You will find such trimmers in armor cores of the SB-1a or SB-12a type. They have an M4 thread and a height of 10 mm.

The loop coils of intermediate frequency filters L5, L7, L9, L11 are wound tightly in a row with PELSHO-0.15 wire, 18 turns each. The communication coils are wound in the same way as the previous ones, with PEL or PEV-0.1 wire. Coil L6 contains 2, L8 and L10 - 3 each, and L11 - 6 turns. Coil L12 contains 2x15 turns. It is wound into two wires at once. The individual parts of the coil are connected in series - the end of one to the beginning of the other.

The intermediate frequency filter coils are equipped with 100NN grade ferrite cores pressed into threaded plastic plugs. Such cores are commercially available and used in short-wave coils of industrial radio receivers “Meridian”, “Russia”, etc. The coils are enclosed in metal screens used in the intermediate frequency circuits of the same receivers.

To ensure inductive coupling between coils L4, L13 and L12, make 5x5 mm holes in the bottom of their screens.

It is advisable to place the high-frequency part on a separate board made of foil getinax or PCB and, after assembly, enclose it in a common rectangular screen, which will facilitate setup.

A low-frequency amplifier can be assembled using a transformerless circuit. It is connected to the IF board at points 4 and “-”.

After installation, start setting up. It can be carried out without a standard signal generator. First, use a DC milliammeter or voltmeter to set the operating modes of the transistors. Collector currents should be in the range of 0.9-1.0 mA. After this, connect an external television antenna to the receiver input, set the tuning cores of the loop coils to the middle position and, by rotating the axis of the capacitor unit, try to tune in to the station. If this fails, then the adjustment should be repeated, only using the tuning core of the local oscillator circuit. Having achieved reception, adjust all circuits to the maximum signal, not forgetting about the sound quality of the transmission. The accuracy of tuning the frequency detector circuit is especially important here.

We will talk about how to make the simplest and cheapest radio transmitter that anyone who doesn’t even understand anything about electronics can assemble.

Reception of such a radio transmitter occurs on a regular radio receiver (on a landline or in a mobile phone), at a frequency of 90-100 MHz. In our case, it will work as a radio extender for headphones from a TV. The radio transmitter is connected via an audio plug to the TV via a headphone jack.

It can be used for different purposes, for example:
1) wireless headphone extender
2) Radio nanny
3) A bug for eavesdropping and so on.

To make it we will need:
1) Soldering iron
2) Wires
3) Audio plug 3.5 mm
4) Batteries
5) Copper varnished wire
6) Glue (Moment or epoxy) but it may not be needed
7) Old boards from a radio or TV (if any)
8) A piece of simple textolite or thick cardboard

Here is his circuit, it is powered by 3-9 volts

The list of radio parts for the circuit is in the photo; they are very common and finding them will not be difficult. Part AMS1117 is not needed (just ignore it)

The coil should be wound according to the following parameters (7-8 turns with a wire with a diameter of 0.6-1 mm, on a mandrel 5mm, I wound it on a drill 5mm)

The ends of the coil must be cleaned of varnish.

A battery housing was used as a housing for the transmitter.

Everything inside was cleaned. For ease of installation

Next, we take the textolite, cut it and drill a lot of holes (it’s better to drill more holes, it will be easier to assemble)

Now we solder all the components according to the diagram

Take the audio plug

And solder the wires to it, which are shown in the diagram as (input)

Next, place the board in the case (it is most reliable to glue it) and connect the battery

Now we connect our transmitter to the TV. On the FM receiver we find a free frequency (one on which there is no radio station) and tune our transmitter to this wave. This is done by a tuned capacitor. We slowly turn it until we hear sound from the TV on the FM receiver.

Our transmitter is now ready for use. To make it convenient to set up the transmitter, I made a hole in the body

Why does the antenna match the 75 ohm cable? My stereo requires a 50 ohm antenna. How to coordinate the antenna and RK-50 cable in this case?
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According to tradition (since the times of the Union), all television antennas are supplied with a cable with a characteristic impedance of 75 Ohms. When using individual television antennas, you can use the same cable and connect the same antennas to the receiver. In practice, you most likely will not notice the difference in the transition from 75 to 50 Ohms (European standard). If you want to do everything honestly, then use Fig. 1.
The balancing-matching device (U - elbow) must be made with a 75 Ohm cable. To the connection point (to the U-elbow), connect a section consisting of two parallel cables with a characteristic impedance of 75 Ohms and a length equal to L2 (Fig. 1), and from this series-connected section lead a reduction cable with a characteristic impedance of 50 Ohms.
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Hello Vyacheslav Yurievich! I think, let me write and ask. As they say, be simpler and people will be drawn to you. I share your position - there is no one to talk to.
My problem is this. I live in the suburbs, the TV signal is not enough. We install amplifiers on the antennas. Something doesn’t work for me, I have to climb onto the roof. And at home there is an indoor antenna with an amplifier, with a clock and a 12 V output. Another ring with a diameter of about 20 cm, as I understand it, for relaying. And I need to make it selective on 24 (498 MHz) and 53 (730 MHz) channels on which digital, terrestrial television is now broadcast in Kursk and thereby increase the signal level.
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Hello.
I recommend checking out the articles on homemade antennas for receiving terrestrial digital television, which are on this blog. Here is the latest article.
"Homemade antenna for receiving terrestrial digital television."
It contains links to previous articles. It will also be useful to read the comments to these articles.
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I hope that a year later, the topic of VHF antennas is still relevant? :)
I encountered the following problem: we often have power cuts at our dacha, we have to turn on inverter lighting, there is 220 volts throughout the house, pure sine, as the inverter manufacturer claims. But here’s a strange thing - the sensitivity of the VHF receiver noticeably decreases, no, those stations that broadcast from 100 to 107 MHz work as if nothing had happened, but those in the 88-94 MHz range practically disappear in the “hiss.”
By the way, the same thing (decrease in sensitivity) was noticed if I connect 12 volt power directly from the battery to the radio, where the batteries should be)
I decided to make an antenna with a discontinuous linear vibrator, according to your formulas, it turns out that the span of one aluminum tube is 163 cm + 4 cm gap + 163 tube, in total, the total length with a gap is 3.3 meters.
The questions are:
1) I think correctly, the total length L includes a gap of 40 mm, then two tubes are added, so what would the total length L be according to the formula?
2) I found aluminum tubes only from curtains, their diameter is 33 mm, not too thick?
3) How is the coaxial cable that fits the music center properly attached? the central wire can simply be connected to the retractable telescopic antenna of the radio or remove it and solder directly to the receiver board. And where to connect the cable sheath?
4) I got the “loop” of the U-elbow of the L1 cable according to the formula of 1.66 meters, as it should be, just hang, straighten it into a ring, an oval, or braid it :), is it important how it will be attached? Or is it the length that matters? Is it possible to fold it in half and tape it to a pole?
5) Should we assume that everything that is soldered or screwed should be well insulated from rain?
6) The dacha is located under a power line, this also affects the quality of reception (although when the power is from the mains, the necessary stations are picked up, but without “stereo”) If the power line affects, then how to remove this influence?
With uv. Alexei. Ural.
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Well, of course! Calculation using your formulas in the pictures. Loop U-elbow L1 (0.75 x 3.33): 1.51 = 1.653 meters. Or as you have L1 = (3x3.33) : 4) : 1.51 = 1.653 meters. Everything is correct, not one meter... although yes, you don’t have the number 0.75, I think it’s 75 ohms, but still, both you and the other formula have the same result - length L1 of the U-elbow = 1.653 meters. And the coefficient of 1.51 has already been applied in the calculations.
Regarding the vibrator, in the picture the formula is L = 3.33: 2 = 1.65 cm. In the formula in the picture there is no division of the resulting amount by another 1.5
Oops:) I WAS WRONG AND I WAS NOT CAREFUL! You have a note below about the coefficient 1.51, which means 1.65: 1.51 = 1.092 meters. This means the length of the tube is 48cm. + 4cm. gap + 48cm. tube = 100 cm. Right? My material will be copper, I couldn’t find aluminum.
And as for the U-elbow, everything is so accurate, I recalculated it again by dividing by a factor of 1.51 L1 = 1.653 cm and L2 = 0.55 cm. Is the total length of the loop twice the span of the vibrator?
Alas, I haven’t seen metallic tubes in our stores, the sellers shrug their shoulders.
Yes, and how did you calculate the overall dimensions of 1350 x 110 of this antenna? And in this U-elbow loop there is no segment L2?
Today they “gave” electricity and the sensitivity of the receiver to the telescopic antenna increased again; before this, the radio was powered by an inverter providing 220 volts. Why is that? The receiver power is 18 watts, the inverter power is 300 watts... it seems, then, what's the difference? inverter or city network? The same effect if I directly connect a 55 ah car battery, the sensitivity also decreases...
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A follow-up question: if there is a special socket for an antenna, then when connecting an external one, in this case, remove the standard telescopic antenna, unsolder it, or simply fold it compactly as provided for in the design for carrying?
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Hello. I suggested that you make a Pistolkors vibrator and the size of the U-elbow loop 1 meter long (half the wavelength taking into account the shortening factor 1.51) refers to it. This antenna is more noise resistant. Everything has been calculated for a long time, there are graphs and tables. The shortening factor in the figure applies only to 75 Ohm coaxial cable and has nothing to do with tubes. Therefore, the span (overall size) of the split vibrator made of two tubes is 1.6 m with a cut of 40 mm.
The overall size of the Pistolkors vibrator turned out to be this way, since with other bends the tube could burst. In practice, at this frequency a peak-to-peak of 0.47 wavelengths is used, and the overall loop width is 80 mm.
Network wires or external power wires affect the parameters of the antenna, being its continuation or, technically speaking, serving as a counterweight. In one case or another, its effectiveness can be worsened or improved, which leads to a change in sensitivity. The location of the receiver and its height relative to the ground also influences.
It is impossible to get pure sine from an inverter. It will still be saturated with short pulses, which create interference over a wide range of frequencies, which directly degrades the sensitivity of the receiver. The wiring from the inverter is an antenna that emits a wide range of interference that falls within the operating range of the receiver.
Usually a switch is installed (two directions with a central position) next to the socket of the external antenna and the built-in one. The central terminal of the switch is connected to the antenna wiring point. All connections are made as short as possible.
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Thanks for the advice! I decided to make two antennas, started with a linear split antenna, and then Pistolkorsa. I'll experiment.
Tell me, how do you solder the braid of a coaxial cable? Somehow, neither rosin nor flux took it, I just had to twist the two ends....
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I unravel the braid of the coaxial cable in the form of a fan, and clean (scrape) with a sharp knife all the veins in different planes. Then I connect the braids of all coaxial cables, spread out like a fan, in a bouquet in one plane so that, if possible, each wire of the fan lies between the wires of another fan, like crossing fingers, and twist the bouquet. I solder the twist obtained in this way. If aluminum tape is additionally used in the coaxial cable, it is not involved in either twisting or soldering. The soldering should be skeletal, that is, each wire should be visible under the layer of solder. It is convenient to use tubular solder with rosin. I strongly do not recommend using active fluxes and acids. For rigidity, I use a metal clamp that tightens all coaxial cables and provides additional electrical contact for the braids.
Good luck!
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Everything worked out!

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Great!
Just in case, let me remind you that the gain of the made antenna and the Pistolkors vibrator loop are the same and amount to 0 dB. The only difference is in noise immunity - the vibrator cable has it better.
1. Don’t worry too much about the diameter of the tube, try it. Stick to dimensions of 0.47 wavelength, which will be 1.44 meters and a vibrator width of 80 cm. The length of the U-elbow remains unchanged - 1 meter.
2. Radio waves propagate over the surface of the metal and everything else has no real basis.
To obtain the antenna gain, if you are not bothered by its dimensions, use the article “Homemade wave channel antenna made of metal plastic.”
There is a drawing of a 4-element antenna. Your vibrator is already made. To obtain antenna gain, a reflector is added, and the antenna already has a one-way directionality and due to this has a gain (5 dB). For greater amplification, directors are installed.
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Everything worked out!
I made the first antenna from an aluminum tube with a diameter of 40 mm, gap 45 mm, span 130 cm.
The range from 88 to 100 MHz came to life, and these are the radio stations of the regional center 70 km from me.
Now I'm planning a Pistolkors vibrator. But there’s a problem here: for some reason we don’t have metal-plastic tubes for sale. I took out a 6 mm copper tube, 310 cm long.
1) can it be used with the same dimensions as in your description or should the dimensions be different?
2) as a child I heard that if you fill the antenna tubes with iron filings, the signal is amplified, but supposedly it causes disturbances for the neighbors, and this, they say, cannot be done, because can be identified and punished. Do you think these are just stories or have a basis in reality?
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Hello, HabarUral.
I'm glad for you that everything worked out. But why the comment is repeated is unclear. However, in my previous comment I made a mistake, 80 cm should be read as 8 cm or 80 mm. In the last century, receiving antennas could create interference due to homemade receivers assembled according to the super-regenerative detector circuit. Due to their simplicity and excellent sensitivity, such receivers were popular among radio amateurs. The disadvantage of such receivers is that they emit a wide range of interference into the air. Yes, it's time to go to another link.
Homemade antenna made of metal for the FM range (87.5 - 108 MHz).
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Vyacheslav Yurievich! Thank you very much! It looks like I don’t need another antenna anymore, today I took the GoldStar car radio instead of the usual Panasonic radio, and lo and behold! The number of radio stations has doubled in the range from 72 to 96 MHz, the quality is excellent. This was not the case at Panasonic, but I was very pleased with that, but here, such a breakthrough! I think that in the car radio, in the circuitry of the radio itself, there are noise-eliminating units (cars still emit interference) or are the quality of older generation receivers better and higher sensitivity? One way or another, GoldStar (now this brand is called LG) settled in my dacha forever, with this antenna (linear split vibrator) in the attic.
With uv. Alexei.
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Vyacheslav Yurievich! Thank you in advance for your topic “Homemade antenna designs for receivers with the VHF (FM) range.” I have little experience in this matter, but I really need an FM antenna (88-108MG) for the SONY ST-A35L tuner (I use 1 meter of wire in place of the antenna). I tried to replicate your antenna from two aluminum tubes (the tubes I used were from ski poles with a diameter of 16mm). The length of each tube was 81 cm (photo 4), the gap between the tubes was 4 cm (everything was done according to photo 6), I used a 75 Ohm television cable, screwed the center of the cable to one aluminum tube, and the braid to the other tube as in photo 6. Connected the other end of the cable to the tuner to the FM connector at 75Om, center for a screw, braid for a clamp. Almost nothing has changed regarding the reception of stations, maybe I did something wrong. I live in a 5-story building with a 9-story building blocking the front.

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Answers

Good day. As I recall, aluminum ski pole tubes are coated with paint or colored varnish that needs to be scraped off for better contact.
Nowadays, most FM transmitters transmit a signal with vertical polarization, so you should try to position the antenna structure vertically. In the case of horizontal polarization, the antenna must be positioned parallel to the ground and its plane oriented towards the transmitter.
If the receiver is on the 5th floor, then you will not notice the difference between the 1 meter wire and this antenna.
These antennas are used when the receiver is at ground level or in a shadow area and by raising the antenna above this level, using a coaxial cable, you can ensure reliable communication with the transmitter.
This antenna has a gain of 0 dB. The gain of multi-element antennas is measured from this design. If you think that the gain in the reception path is not enough, then you need to make a multi-element antenna. for example, “wave channel”, it is also called “Uda-Yagi” or “Yagi”.
When making a conventional split vibrator, it would be more correct to use Figure 1.

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Good day! I sanded the ski pole tubes at the cable connection points. The receiver is located on the 3rd floor (a building of 5 floors) in a room 3 by 4 meters near the window, from the window in front there is a 9-story building about 200 meters away. There is no way to place the antenna on the roof. There are 5 LEDs on the receiver that show the received signal (on almost all radio stations that my receiver receives, only one LED lights up, sometimes in the evening two LEDs). You're probably right, I need to build an antenna with high gain. Can you give me a link for the antenna?

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Hello. When receiving a radio station, have you tried positioning the antenna vertically (braid at the bottom), and then horizontally? How did different antenna positions affect the level indicator (on the bulbs)? In the case of horizontal polarization of the transmitter, the antenna should be rotated (without touching it with your hands) in a horizontal plane to find the maximum reception level in order to ensure its optimal orientation towards the transmitter.
The best results are obtained with the antenna in photo 12, although theoretically such an antenna also has no gain. Perhaps the material (plastic metal) from which it is made plays an important role here.
Homemade plastic antenna for FM band.
Antennas are more complex, that is, antennas with amplification, at these frequencies they are larger in size, but purely for reference, I present a drawing of a “wave channel” antenna. He's in this post
Homemade decimeter “wave channel” antenna made of plastic.
The dimensions of the vibrator and reflector and the distances between them are in the previous post. Everything else can be easily calculated from the drawing.

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I have a Technix music center. The frequency range stretches from 66 to 108, second floor, northwest, shadow zone. In the room I receive confidently on frequencies 101-108, stations of interest to me in the ranges 71-94, continuous hiss. I noticed that if I turn on a laptop, and even more so an additional monitor to it, the interference increases. What I did was take an ordinary telescopic indoor TV antenna and put it on the balcony, the reception improved, but there was no stereo, then I just took a pole and moved the antenna one and a half meters outside the balcony, twisted it - the reception became simply gorgeous! Apparently you have the same problem - interference from household appliances, equipment and wiring, perhaps your neighbor has a computer with a monitor behind the wall, opposite your tuner. Try to move the antenna outside the wall of the house, just open the window, attach the antenna and place the structure outside the window, rotate it... I’m sure the reception will improve. And then, it’s a matter of technology to consolidate it all.

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Hello. I tried turning the antenna to horizontal and vertical positions, carried it around the room, there was no strong effect. One thing I noticed was that the gain did not increase, but there was less interference in the reception, and at some stations the gain decreased. I’ll also try HabarUral’s advice - take it out the window. There is also an idea to install an amplifier from a Polish antenna on the antenna.

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Thanks for the article on the topic of FM antennas for tuners. I made a split antenna from 16 mm aluminum tubes, but did not get any effect. I would be grateful if you give me advice on what’s wrong or “how to do it right.”
Apartment in the center of Samara, house on a high point, floor 11, walls are silicate brick, but all loggias are lined with corrugated board (this is almost the entire perimeter of the apartment, with windows). According to my concepts, the signal should be very good. YMAHA tuner, sensitivity characteristics below:
SECTION FM
Setting range
[USA and Canada models] ................... 87.5 – 107.9 MHz
[Other models] ................................... 87.50 – 108.00 MHz
50 dB Quiet Sensitivity (IHF, 100% mod.)
Mono/Stereo............... 2.0 mV (17.3 dBf) /25 mV (39.2 dBf)
Selectivity (400 kHz) .................................................. 70 dB
Signal to Noise Ratio (IHF)
Mono/Stereo................................................... .... 76 dB/70 dB
Harmonic distortion (1 kHz)
Mono/Stereo................................................... ......0.2%/0.3%
Stereo separation (1 kHz) .................. 42 dB
Frequency response......20 Hz – 15 kHz +0.5, –2 dB
The reception on the original wired antenna (about 1.4 meters) is noisy; when the wire is mounted vertically, the reception is better; my “walking” nearby affects the quality of reception and interference.
I made the antenna according to your recommendations, everything works, but not much better than the standard wire antenna.
There is also interference, the antenna orientation is vertical. The upper tube is connected to the central copper core, the lower one is connected to the braided 75 Ohm cable, the cable itself is run through the lower tube for convenience (inside the tube) - perhaps this is an error. Perhaps there is a lot of interference in the house and the reason for this is that only about 10 Wi-Fi networks (transmitters) are “visible” at a given point in the apartment. (a couple of mine and from neighbors).
I wanted to attach a photo of the antenna and its location, but I couldn’t do it in this blog window.
I will be a slave if you give me your email address, I can send you a photo.

Sincerely,
Alexei
[email protected]

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Vyacheslav Yurievich, good afternoon.
Thanks for your answer. There is no error with the sensitivity of the tuner, I checked it according to the original instructions (of course, there may be an error there too. I will think about moving the antenna to the external wall of the house, although this is not easy, if you do it well you have to hang out of the window on ropes, and this is the 11th floor.
Please answer a few questions.

1) I ran a 75 ohm cable inside the antenna tube connected to the outer braid - in theory, could this affect the quality of the antenna or not?

3) I saw on sale a 75 ohm coaxial cable with two shields (central core, insulation, first shield, insulation, second shield, outer insulation). Using such a cable can you reduce interference?

Sincerely,
Alexei
[email protected]

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Vyacheslav Yurievich, good afternoon.

Thanks for answers. I will make an external antenna on the facade. I will place 81 cm aluminum tubes inside a polypropylene (non-reinforced) water pipe, with a 4 cm PCB cylinder between them. The external pipe will protect the antenna from precipitation and other things.

1) Is there a difference between which tubes to use, aluminum or copper (both 14 mm with a 1 mm wall)?
2) When using a cable with two screens, should both screens be connected to the antenna beam (aluminum tube)? or as an option only an external screen (or an internal screen)?

Sincerely,
Alexei
[email protected]

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Vyacheslav Yurievich, good afternoon.
The question is purely theoretical.
Initial data: I live in the regional center, on the 8th floor in the shadow zone of FM radio transmitters. Radio transmitters are on the hill and in front of it, the house is behind the hill. The height of the hill is 150 meters. The house is 70-80 meters lower from the highest point of the hill. In the direction of the transmitters there are reinforced concrete houses. There is no direct visibility to the transmitting antennas either from these houses or from my apartment. There are 15 FM stations in the city. The external antenna of the receiver (wires 145 mm) picks up 12 and 3 in stereo mode. I installed the antenna (180 cm copper wire with a diameter of 4 mm insulated) and screwed the central core of the RK-75 wire to one end of the wire without soldering. The 75 ohm cable braid wire was left idle - not screwed on. external receiver antenna input - 75 ohm. He took the resulting vibrator to the balcony - 100 cm from the wall of the building. All 15 stations work in stereo mode.

The inconvenience is that the vibrator on the balcony takes up a lot of space (it was placed both vertically and horizontally).

The question itself is whether it is possible to make the antenna smaller by leaving 75 cm of copper wire (a quarter wave of the mid-FM range), located vertically, and the rest of it - 105 cm - twisted at 90 degrees in the form of a spiral with a diameter of 8-10 cm (you get 4-5 turns for the antenna base)? Should I use a braided coaxial cable (can be screwed to a copper wire 24 mm from the point where the central core of the feeder is attached (as in an antenna with foil)? Will there be an effect from such an upgrade?

Theoretical question - between the buildings there is a gap of about 100 meters into an open field, in the opposite direction from the transmitting antennas of our city, 80 km away there is another regional center. If I use a directional UHF television antenna with an amplifier (11 reflectors and a director) powered from 220 volts towards the gap between houses in another regional center, will I be able to hear radio stations of another city in the same quality as from the transmitters of my city? The UHF TV antenna in the village requires dismantling, which is why the question is theoretical. Thanks for the help.
Andrey.

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Answers

Hello Andrei. In theory, a quarter-wave length of wire is used, in this case its length should be 75 cm (for 100 MHz). Such a piece of wire will work as an antenna if it is directly inserted into the antenna socket of the receiver. When connecting a wire to a coaxial cable, it needs a counterweight. These are 3 - 4 pieces of wire equal in length (about 75 cm), attached to the cable braid, at the junction of the central conductor, and directed downward at 120 degrees from the vertical, with equal beams. Such an antenna will be called Ground plane (see the request for pictures). The wire is much inferior compared to a telescopic antenna, since it has a matching range with the input of about 10 MHz and, in this case, a tube made of brass, copper, or aluminum works better (good antennas are made from plastic). Taking into account the shortening coefficient, as the diameter of the tube increases, its length decreases. To simplify the solution of the problem, instead of counterweight beams, a larger diameter tube of the vibrator itself is used, through which a coaxial cable is passed.
I do not recommend using a decimeter antenna, even if it has a meter wave range of 56 MHz - 250 MHz (a split vibrator with a span of 2 meters).
I recommend additionally using a reflector (reflector), as shown in photo 10. I used an aluminum building rule as a reflector. This can be a metal stick about 1.5 meters long, installed parallel to the vibrator at a distance of 45 - 60 cm, behind it. Such a reflector, combined with a vibrator, gives a gain of as much as 5 dB.
The lack of stereophonic mode of some stations indoors is possible due to the presence of interference that creates an overload of the input path. In this case, preference should be given to frame or loop antennas. Try a loop antenna. This is a ring of wire 2.7 meters long, connected directly to the antenna socket of the receiver (body and center).
By the way, I’m preparing a post on the loop antenna; I think it will be sent to the main page in a week. Compared to a telescopic antenna, the frame performs much better in interference conditions.

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Vyacheslav Yurievich, good afternoon.
Thanks for the complete answer. I'm also making progress. I’ll tell you about them and ask you to evaluate what has been done in terms of improving the design of the antenna from the available materials, which I’ll talk about below.
So, from a 4 mm copper wire in a vinyl braid, 180 cm long, I made a vibrator (75 cm) and twisted the remainder (105 cm) into a spiral as a base (stand) for the vibrator. The result was a stand of 3 full circles (on average 35 cm in circumference). To the receiver, at the input of the external antenna, I connected the RK-75 cable (with a diameter of 2 mm - the size of a match for removal through the balcony door without drilling additional holes). Type F PRM socket. Antenna cable 20 meters long (from a radio store from the 80s). He pulled him around the room and led him out onto the balcony. I twisted the remainder into a circle of the same diameter as the coils of the copper rod and put it on the vibrator, pressing the spiral base of the antenna. I connected the feeder and the vibrator like this: the central core at the point where the copper wire was bent by 75 cm (it turned out to be 1/4 of the wavelength of the middle FM range), the feeder braid was connected to the end of the copper wire on the opposite side of the vibrator, at the end of the base spiral. I didn’t solder anything, just twisted. I placed the resulting antenna on the balcony, on the windowsill at the very corner. The balcony is glazed with metal-plastic windows. The distance from the concrete wall of the house to the antenna is 110 cm. Since the antenna is installed in the corner of the balcony, the aluminum edges of the balcony windows serve as a screen. The distance between the vibrator and the windows is 8-10 cm.
Result. I catch all FM stations in my city in stereo mode, 15 stations. Plus two stations of the regional center, located 40 km away. They broadcast on their FM frequencies in stereo mode, but I catch them in mono mode and one unknown station in good mono quality from a neighboring area. Total - 18 stations. Additional stations are a result of the reflection of waves from neighboring houses located 10-12 meters above mine. The district center is located on the opposite side of the reinforced concrete building. That is, I’m quite pleased with the result, but I’m still itching to improve something with wave reception without moving the antenna outside the balcony.
What can be done:
1. Shield the spiral under the vibrator at a distance of 75 cm and change the connection of the feeder braid to the created shield.
2. Reduce the length of the feeder without forming turns of wire on the base of the vibrator to 7 meters (I don’t plan to increase the thickness of the RK-75 wire - it’s too thick, this did not improve the reception, I tried).
3. Make a full-fledged dipole of 1/4 wavelength from a PVC water pipe by winding copper wire with a diameter of 2 mm onto a 20 mm PVC pipe 75 cm long on both sides.
4. Make a Pistolsky vibrator with U matching from a metal-plastic pipe.

Is it possible to improve an existing antenna with little effort?
Andrey.

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Hello Andrei.
At the end of this post I have placed figure #3 “Double Helix Antenna”. If something like this happens, it won’t get any better. All antennas discussed in this post, be it a split vibrator or a Pistolkors loop, are single-element antennas and have virtually no gain. So, the Pistolkors loop has a gain of 0 dB, and from this (it is considered ideal) antenna the gain of all other antennas is measured. Only then will the antenna have gain when it has a unidirectional pattern, for example, due to a reflector or directors.
Finally, I didn't understand. In order not to take the antenna out onto the balcony, did you try connecting directly to the antenna socket of the receiver: a quarter-wavelength piece of wire (75 cm), tubes, spirals, a wave ring (2.7 m)? After all, you can receive the reflected signal from houses.
As a quarter-wave segment or loop, I used coaxial cable, the conductive layer of which is the outer braid.

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Thanks for the consultation. Yes, apparently, the result is a double helical antenna, maybe not exactly exactly in size, but the reception quality is quite satisfactory for city stations. And for long-distance reception there is Internet and AUX input of the receiver. Andrey.

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Vyacheslav Yurievich, good afternoon.
The antenna itch does not go away. No longer in terms of receiving FM radio waves, I’ve already “played enough” with this, creating 6 types of antennas for my receiver. Trouble came from unexpected places. my wife says - remove your trash from the balcony or make an acceptable antenna for my eye on the balcony and your receiver.
We agreed that a PVC pipe standing in the corner of the balcony would suit it (in the corner - away from the wall of the house at a distance of 110 cm). There is no point in taking the antenna outside, because... I achieved reception of all radio stations in my city in stereo mode using various antennas placed on the balcony.
What options do I have: PVC pipe (not metal), i.e. radiotransparent. The internal diameter is 10 mm. There is a 2 mm braided wire from a 380 volt electric cable about 12 meters long, and a 4 mm braided RK-75 cable. There is a desire to place the antenna inside a PVC pipe (we ensure aesthetics) and the task is to ensure maximum quality of reception of FM radio stations in your city.
Reception results achieved with existing and previously made antennas:
1. Internal antenna of the receiver - 3 stations in stereo mode - 9 in mono.
2. External antenna 145 mm made of wire and an “F” type connector (came with the receiver) - 12 stereo stations, 3 mono stations. Sensitive to people walking around the room, because... without braid.
3. 180 cm pin on the balcony (4 mm braided copper wire) - 15 stations in stereo mode.
4. Homemade from a 180 cm pin - 75 cm vibrator and the rest in the form of 3 spirals under the base - 13 stations in stereo and 3 stations in mono (2 stations from the neighboring region).
5. Dippole from the RK-75 cable (we attach 75 cm of the braid without turning it out, but by screwing it with tape to the feeder below 75 cm of the vibrator - the central core of the RK-75 cable) - 15 stations in stereo and 2 stations in mono mode (2 stations from a neighboring region ).
6. Pistolkorsa vibrator made of metal-plastic pipe, as you showed above. Pipe with a diameter of 20 mm. Therefore, the dimensions turned out to be slightly different than in your article: length 139 cm, width 110 mm with the coordination of a U-elbow 1 meter long - I didn’t get the “WOW” effect, except for a blow to the head with a rolling pin for the loss of aesthetics on balcony from his wife demanding that this monster be removed from the balcony. In fact - 15 stations in stereo, 3 stations in mono (3 stations in the neighboring region). The bandwidth in which the station is caught in stereo mode has increased to +/- 0.5 MHz. At first I was happy about this, but then I realized that it was bad. The selectivity of the receiver deteriorated - the stations began to overlap one another, because they are densely located on the radio (102.2 and 102.7; 105.7 and 105.9; 106.6 and 106.8; 106.8 and 107.2). In this case, it took longer than usual to tune the receiver to the desired frequency with a vernier. From this I concluded that it is better to have a less powerful antenna. Although, according to theory, all antennas without a reflector and director have a gain of 0 dB.
Now the main thing is the question itself for you.
Which option would be better given the initial data described above, so as not to spoil the material once again:
1. Place the dipole from the RK-75 antenna cable in a plastic pipe and that’s it - it’s easy to move the PVC pipe with the cable below along the balcony and install it to the desired height without gluing the wire to the glass with tape.
2. Bend a piece of RK-75 wire 3 meters long in half and place it inside a plastic pipe. Connect the braid and the central core of the RK-75 cable placed in the pipe. Connect the other end of this loop with a length of L/2 to the feeder: one to the central core, and the other to the braid without a matching U-elbow. L-300 cm - wavelength of the middle FM range.
3. It differs from the 2nd in that instead of a loop we make a cable break at the top of the pipe and get a dipole with a length of L/2 with the only difference being that the counterweight of the vibrator is rotated 180 degrees, i.e. both the vibrator and the counterweight are located parallel inside the PVC pipe, and not rotated 180 degrees.
What is your advice?
With all respect, Andrew.
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Hello Andrei.
At the end of the post I placed Figure 4. Try to assemble and test such an antenna. Half of the plastic tube must be covered with food-grade aluminum foil, and the braid of the coaxial cable must be tightened to the foil with a clamp. You will have to make a hole in the middle of the tube in order to pull out the braid of the coaxial cable and solder the vibrator. To avoid spoiling the material, first make a mock-up of the antenna using cardboard. Good luck.
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I'll try this antenna. Best the enemy of the good. My plastic PVC pipe (for plumbing for soldering) also turned out to be aluminum! I discovered the shine when making a hole for the cable at the very edge under the plastic. Desperate. Then I put the antenna inside the PVC pipe according to point 5 of my previous post (quarter-wave dipole on a coaxial cable). I thought that since there was a screen, the reception had worsened, but unexpectedly for me it improved: there were more stations in another region and stations in my city all worked in stereo mode. Wow! There is no electrical connection between the braid and the central core with the pipe at my dipole. There can only be leads. But what an effect! How can I try the proposed antenna in Fig. 4 articles - I’ll unsubscribe.
With all respect, Andrew.
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I'm reporting. The antenna option according to Figure 4 works worse than the dipole option according to point 5 of my post dated 7.2.18 11:16. How does this manifest itself? Stations not in your region have disappeared. City stations are all in stereo. Does copper braided foil work poorly? I wound the foil around the cable, secured the cable braid between the turns of foil and tightened it with tape. I also wrapped the entire length of the cable in foil with tape. On the vibrator, I connected the braid to the central core. I kept the dimensions of the vibrator (700 mm), the gap with the counterweight (40 mm) and the counterweight itself (750 mm) as in Figure 4. I placed it in a plastic pipe - I did not notice any improvements.
I wanted to try a half-wave vibrator fed from one end, but I read on the Internet that it works no better than a quarter-wave dipole and needs to be adjusted by the transformer. Although it has a good radiation pattern (pressed to the ground) and reviews from practicing radio amateurs.
There is cable left for one more experiment. Which one will we conduct? I am inclined to option 2 of my previous experimental plan, namely: “2. Bend a piece of RK-75 wire 3 meters long in half and place it inside a plastic pipe. Connect the braid and the central core of the RK-75 cable placed in the pipe. The other end of this loop length L/2 connect to the feeder: one to the central core, and the other to the braid without a matching U-elbow L-300 cm - wavelength of the middle FM range." Do you approve, from the point of view of theory and your practice?
With all respect, Andrew.

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OK. Let's correct the technology, try to connect the cable braid to foil wound around a 75 cm pipe and covered with tape. At the same time, we take the vibrator outside the pipe and attach it to any dielectric inserted into the pipe. For example, we attach a vibrator to a dielectric to a stick 40-60 cm long with tape. The height of the structure will be: 200 cm pipe + 70 cm vibrator.

If, in any case, our pipe has an aluminum layer in a polyurethane foam environment (PP-R/AL/PP-R - this is the pipe marking I have), then how does the option you propose differ from a split quarter-wave dipole on a metal-plastic white pipe or not? split dipole, which works well for me on a regular RK-75-4 at a minimum cost?

You can eliminate aluminum in the pipe only by using a plastic cable channel for the wires, choosing a 20 mm square side, and place the cable channel itself in insulation (we make the counterweight thicker), on which we wrap 75 cm of food foil and connect it to the cable braid. The diameter of such a design will be 35-40 mm and under the foil - 25-30 mm. Then it will be a pure experiment, but there is no aesthetics in it.
With all respect, Andrew.

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I made an antenna according to Fig. 4 of the article text using your technology. I wound 75 cm foil around the pipe. I screwed the RK-75 cable braid to it with tape through a couple more turns of foil. I secured the connection with electrical tape and tape. Since the pipe is PVC with aluminum, I moved the vibrator outside the pipe. I inserted a suitable stick into the pipe from the side of the screwed foil and tied the vibrator to it with electrical tape (70 cm + 4 cm gap). Together with the pipe and vibrator, we got a 2-meter structure (another piece of pipe). Technologically, such an antenna turned out to be more complicated than a continuous dipole made of coaxial cable, where the braid is removed from the vibrator - the central core of the RK-75 cable and tied to the external insulation of the feeder with electrical contact of the braid without breaking. The second part of the dipole obtained in this way is attached to the cable with tape along the entire length of 75 cm from the point where the braid is removed from the cable. 75 cm central core insulated and 75 cm braid removed from the cable and twisted into copper wire about 2 mm thick. Mechanically this wire was connected to the braid. This is instead of a “stocking”, made of braid, turned back (I couldn’t do that). I chose this antenna as a basis for comparison based on the sounding method of stations not in my region and high-frequency interference between stations (analog tuner).

Result: The antenna-base of the comparison catches 12 stations in stereo and 3 stations in mono not of its region in decent quality. Dipole design with foil wound to the pipe - 12 stations in stereo mode and 1 station in decent quality outside of its region in mono mode. The high-frequency whistle is higher when moving from station to station on this antenna. Since there are two antennas next to each other on the balcony and I only switch to an external antenna on the receiver, first one antenna, then the other, I can compare without losing the feeling of reception from the previous antenna. The wires are the same RK-75-4. The feeder length of the comparison base antenna is 2 meters less. The total length of the wires is 5 and 7 meters.
The pipe is 200 cm, so with a vibrator it is 270 cm, so as not to make holes in it, since it is made of aluminum. But I found a piece of the same pipe, but shorter, and with a vibrator the result was a structure equal to the first antenna - 2 meters each. The feeder passes through the pipe in both cases. In principle, no miracle happened. Both antennas are approximately the same (all are twisted without soldering, due to this the second antenna produces more interference and the cable is also longer. The cables are connected to the receiver with standard different “F” connectors).

I'll try another antenna option and finish with the experiments. Thanks for the help and advice.
With all respect, Andrew.

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Still, the antenna shown in Figure 4 of the article works better. If you create equal conditions and remove the PVC pipe from the comparison base antenna, then it does not catch 3 stations of the neighboring region, but only its 12 stations in stereo mode with the same interference (HF whistle between stations). I wrote about the pipe above - it serves as a screen for removing HF interference in a continuous dipole, and in the antenna as shown in Fig. 4 articles there is no such screen for a vibrator. Under equal experimental conditions, everything changed exactly the opposite.

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The new antenna is based on the Pistolkors vibrator. PVC pipe (green, not metal-plastic) with a diameter of 20 mm, length 2000 mm. The wire from under the 380 volt cable is multi-core - 16 1.5 mm copper wires woven into one insulating sheath. A bit heavy in weight. I cut off 3 meters. At the ends I make a ring for fastening a coaxial cable with a diameter of 3 mm. I divide the wire in half (bend it). I slightly shift one side relative to the other so that there is a distance of 40 mm between the rings when the loop is fully extended. Starting from the end, I tie a wire to the PVC pipe on two opposite sides of the pipe, at 180 degrees. I pull it and secure it after 10-15 cm with electrical tape or tape. And so on until the end of the wires (to the rings). The result was a loop with the following dimensions: wire thickness 6 mm in rubberized insulation, distance between wires - 20 mm, taking into account insulation - 23-24 mm. I am making a meter-long matching device from a piece of RK-75 coaxial cable. I fold a piece of 110 mm cable in half and tie it with electrical tape (10 mm per twist of the central core). The result was 500 mm. I connect one central core of the matching device to one end of the loop (by simple twisting), and connect the other end of the loop to the second central core of the matching device. I connect the central core of the RK-75-4 coaxial cable with a copper mesh braid to one loop ring (any). I connect the three ends of the braid (two from the matching device and one from the coaxial cable) by twisting and wrapping them with 40 mm wide food foil several turns and securing them with electrical tape. The distance between the loop rings is 40 mm (one is higher than the other along the pipe on opposite sides). I connect the cable to the matching device in three places with electrical tape. I attach the entire structure of the matching device with the cable to the PVC pipe with electrical tape or tape. The whole structure turned out to be exactly 2000 mm (1500 mm antenna and 500 mm matching device). I connect it to an FM stereo receiver and an external antenna via an “F” type connector. I take the antenna out onto the balcony and place it vertically in the corner of the balcony, where I placed all previous antennas. There, an artificial reflector is obtained from the junction of two metal-plastic frames and an aluminum connector. I turn on the receiver.

3-4 stations are caught in stereo, the rest in mono mode. The result did not satisfy me. I turned the antenna horizontally, placed it on the window sill of the balcony and pointed it into the sky. I started turning the receiver's vernier and a miracle happened. Stations in stereo mode sound like you're sitting in a concert hall. Deep stereo effect, no interference and clear sound. I achieved this after 2 weeks of experimenting with different antennas.
Compared with the antenna in Fig. 4 of the article. The sound in stereo mode is significantly different from the new antenna - the sound is quieter and there is no such depth of the stereo effect, although the stereo signal in the form of a light bulb lights up without blinking, i.e. The wave tuning is good.

Peculiarities. The antenna turned out to be narrowly directional with good noise reduction, and due to the aluminum core in the form of a PVC pipe, also with amplification, apparently. It also works at an angle of 45 degrees, but not all stations are in stereo mode.
Here is the experience of experimental selection of antennas for urban listening to stereo FM. Receiver - Sangean WR-12. The cable waited in the wings for 30 years and finally brought benefit to the owner.
Thank you for your attention.
Laying technology. We ideally need to lay the wire in the form of a rectangle, where the height is 2 times greater than the base. We make a 2 cm gap on one of the vertical sides - in the middle. For a wire of 306 cm we get a rectangle: 306/2/3=51 cm - this is the length of the base. 51*2 = 102 is the height of the frame. Why exactly this frame size - no matching devices are needed. At the point where the coaxial cable is connected there will be a resistance of 75 ohms. We attach the cable to the frame like this: a braid to one end of the break on one side of the frame, and a central core to the other end. These are ideal laying conditions. But if the window is already 51 cm or 1-2 cm wider, then you have to fit the frame along the width of the window (up to the glazing beads on the wooden frame, and for plastic windows - up to the glass holders-clips).

As I did, I measured the width and height of the plastic window using the glass. One was 51.5 cm wide and 130 cm high, and the adjacent one was 3 cm smaller in width. I had to make two frames on adjacent windows and, in addition, the windows were located at 90 degrees - this is the angle of the balcony. I measured 50 cm up from the bottom of the window along the glass and secured one of the ends of the wire with ordinary tape, making a 1 cm turn towards the window frame at 90 degrees. Then we lay the wire down to the end of the window, i.e. to its bottom. We secured the corner with tape. We walked along the bottom to the opposite side of the frame - we got the bottom of the frame and half of one side of the frame with a gap for the cable. We laid the wire up to a height of 102 cm. We secured the corner with tape - the upper corner of the frame. Then horizontally to the opposite side of the frame. We secured the corner and down until it broke. To create a gap of 2 cm in the gap of the side (I have the right side of the first frame), we bend the wire towards the plastic of the frame and secure the gap with tape, leaving the bare ends of the wire for attaching a coaxial cable with a resistance of 75 ohms. To prevent the wire from sagging, we secure it with tape every 10-15 cm, both vertically and horizontally. We do not connect the cable.

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We attach the second piece of wire 306 cm to the adjacent window, but using a different technology. We need to connect two frames to one cable, so we tape the break of the second wire to the plastic frame with tape (it will be 2 cm). We got wires 2 cm parallel to each other along the width of the frame, 7 cm, and in the center there was a place for connecting the cable to the receiver. Next, we stretch the wire around the perimeter of the window to create a frame with identical bottom and top sides. First we fasten the corners, and then the wire between the corners is 10-15 cm.

We get two frames on adjacent windows, but one is strictly along a rectangle of 51 X 102 cm, and the other is smaller, by stretching the gap until it connects with the gap of the side of the other frame (I got 7 cm according to the width of the window frame). We connect the coax with two frames at the break point. I connected the central core at the top, and the braid at the bottom of the gap. I twisted the wires - they are all copper. It is clear that it is not worth and not worth soldering on the window.

The direction of the frames is one at 30 degrees to the tower of the transmitting center, and the other at 120 degrees. At a distance of 110 cm behind the first frame there is a concrete wall of the building that serves as a reflector. At a distance of 320 cm, another concrete wall of the building is a reflector for the second frame. Since the two frames on the windows are at an angle of 90 degrees and with reflectors, the main lobe of the radiation pattern of the two frames turned out to be at an angle from the transmitting center by 80-90 degrees from the transmitting center. Polarization - vertical of two frames, because the gap is at the height, not at the base of the rectangular frame.

As a result, all the radio stations in your city are in stereo mode with good sound depth and stereo effect. We catch repeaters on other frequencies of regional centers and 2 programs from a neighboring region in stereo mode. The best antenna I have tested and described above.

We improve the stereo effect due to the capacitive component and the width of the frame wire. I replaced the usual 1 mm thick wire under the frame with a double 1.5 mm wire, each wire of the wave rope type (noodles). I connected the ends of the parallel wires at the junction with the coaxial cable and laid the wires instead of the previously used ones. Two pieces of double cable, 306 cm each. I got a better stereo effect and a slightly wider radiation pattern, judging by the volume of poorly received radio stations from repeaters of regional centers (it decreased). I decided not to change the wire back (to a single-core one).
I am writing for those who want to have a do-it-yourself antenna in the form of frames on a balcony window.

With all respect, Andrew

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FM antenna based on an antenna made from beer cans, but without them.
TV antennas with horizontal polarization are made from beer cans. For FM reception you need a vertical one.
I decided to conduct an experiment with water bottles (1.5 liters plastic). I poured about 1 liter of water into one (for the stability of the structure). The caps of two bottles were fastened together with a bolt and a washer in the center. I screwed the fastened caps onto an empty 1.5 liter bottle, and the second onto a bottle of water. We got one plastic bottle standing on top of another. Take foil for baking (I have foil 29 cm wide and 11 microns thick). I screwed 3 turns onto the bottom bottle (it turned out from the very bottom to 2 cm from the cap). I secured the foil with tape in 3 places: in the center, from the edge near the bottom and 2 cm from the edge of the foil near the lid. He took off the top bottle and did the same to it. He screwed on the cap and connected the two bottles. We take a 75 ohm coaxial cable and make a U type matching device 1 meter long. We connect it with a twist to a coaxial cable: three braids together; twist two central cores (one from the feeder and the other from the matching device) together and leave a free end of 3 cm for attachment to the foil; We expose the central core of the second end of the matching device 3 cm. We connect everything like this: we insert two twisted central cores between the turns of foil on the bottom bottle and tighten them with tape, pressing them against the bottle; we do the same with a piece of wire 7-10 cm long and attach one end of it to the second, top bottle. We needed a piece of wire so that we could unscrew the bottles and replace the water with sand when it dried out from the snow. We connect the second end of the wiring with a twist to the free central core of the matching device. That's it - the antenna is ready. We are conducting tests. I screwed the matching device with tape to the bottom can, although it would be correct to place it at 90 degrees to the bottles. We are looking for a place on the balcony, on the windowsill. The directional pattern is circular at the antenna, moving the bottles at a distance of 39 cm from the reinforced concrete wall - we get a directional pattern away from the reinforced concrete wall (39 cm is 0.13 wavelengths in the 300 cm (mid-FM) range). We select the height of installation of the bottles on the windowsill so that they are in the middle between the ceiling (reinforced concrete slab) and the floor - the same slab. We turn on the receiver - all city FM stations in stereo mode across the entire width of the FM range from 88 to 108 MHz. The stereo sound in the receiver is not flat, it is voluminous, comparable to the stereo sound from a double square antenna (my post above from February 21). the distance between the foil of the two bottles was 10 cm between the points of attachment of the feeder to the foil (recommended 7.5). It is clear that it will not be possible to conduct an experiment by reducing this distance. In general, for a portable receiver one of the options is an external antenna.

3. For better contact between the braid and the central core of the cable to the foil (without a matching device, we attach the central wire and the braid to different bottles between the turns of foil) - screwed M6 washers and then inserted them between the turns of the braid to a depth of 1 cm and pressed them with tape to the bottle in 2 turns.
4. The height of the structure is 66 cm, the circumference of the bottles is 28 cm. The bottles are without a narrowing at the arm in the middle of the bottle.
5. The foil can be tied to a cardboard tube, leaving a gap between the turns of foil of 7.5 - 10 cm (the larger the diameter of the tube, the greater the distance between the ends of the foil). Foil can be glued to cardboard, but this results in a lot of glue consumption. Since the foil clings to objects during transportation and breaks, it is better to wrap it with tape along its entire length.
With all respect, Andrew.

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Good afternoon, V.Yu.
We are switching to magnetic antennas for receiving FM radio stations in dense buildings and balcony-window options. I made a frame antenna from one piece of copper wire with a diameter of 3 mm for a balcony glass with a perimeter of 306 cm with a gap in the larger side of the rectangle (43x110, gap 2 cm). I replaced a previously installed antenna of the same size, but made of flexible wire 2x1.5 mm. The results didn't impress me. The antenna turned out to be narrowband (the setting was 100 MHz). At frequencies above 107 and below 97 MHz, significant signal attenuation was felt. I read that a loop antenna with a frame perimeter of less than a quarter of the wavelength is more sensitive to the magnetic component of the wave rather than the electrical one. The second premise is that at frequencies that are multiples of the wavelength there is resonance. A loop antenna is effective when the frame perimeter is equal to the wavelength. An idea arose - to make a frame at a frequency that is a multiple of the wavelength, but less than a quarter.
I started counting - 100 MHz - the average frequency of the FM range (with a wavelength of 300 cm), but what if we increase the frequency 5 times? We get 500 MHz and a wavelength of 60 cm. Then the frame is obtained with sides of 10x20 cm. With such aspect ratios, no coordination is required. We will make a gap on one of the small sides of the rectangle of 2 cm (we cut and bend the wire to the sides 1 cm each). In fact, we begin to bend the wire (Ф=3mm) from one end: 1-4-20-10-20-4-1 = 60 cm. Since I do not encourage soldering in experiments, I used a 1 cm vinyl braided wire as a clamping device. I inserted the central core of the coax into it and secured it (pulled it) onto the end of the frame. Coaxial braid to the other end of the frame. That's it - the antenna is ready. RK-75 cable with copper braiding (so that the antenna and coaxial material are the same). Cable length - 40 cm (there was just such a piece without use). Started testing.
A room in a reinforced concrete house. no result. It catches something, but there are dips in the signal level from different stations.
I went out onto the balcony with the antenna - I placed it next to the metal-plastic frame on the windowsill and also in the corner of the balcony (slab on top, slab below, balcony wall - reinforced concrete), 0.17 wavelength from the wall - 50 cm.
And then the bite began - I didn’t have time to shoot both large and very large fish, in the sense of an FM station one after another with a high signal level. All stations are in stereo mode in their city and a couple of stations in mono in the neighboring region (80 km).
I continued testing by moving the frame on the windowsill up and down, left and right. I found out that the closer to the metal-plastic window, the better the signal. I calculated the distance from the reinforced concrete wall correctly. Elsewhere the signal weakened, but was not comparable to the signal level in the room. I left the frame in the place with the strongest signal level and connected a cable 11 meters long. I’m sitting in the room listening to such a small antenna and enjoying the signal level and sound quality. The signal level in dB for all stations is 475 dB, and a metal-plastic phased antenna with circles of 73.5 cm showed the result on the same balcony, but in a different place (opposite) - 479 dB. But the dimensions are not comparable on the balcony. I received gratitude for this from my wife.
This is how scraps of knowledge of radio engineering synthesized in practice an antenna suitable for use in my conditions. Practice is the criterion of truth!!!
Thanks for the site and creative ideas for new developments.
Andrey.

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Radio broadcasting on ultrashort waves is carried out using frequency modulation (FM) and occupies the following frequency bands:

VHF – 65.9-74 MHz
FM1 – 87.5-95 MHz
FM2 – 98-108 MHz

The VHF band was used in Soviet times and is currently used in Russia. Radio stations from other countries operate in the FM bands. It’s not difficult to make a tube radio receiver with your own hands.. The main difficulties lie in setting up and adjusting the design. If audio equipment can be adjusted by ear, since it is easy to check the presence and passage of a signal through the circuits, then to configure radio wave devices you will need a SSG (Standard Signal Generator) and an oscilloscope. GSS will allow you to configure radio receiving devices operating in all radio bands with amplitude or frequency modulation. If precise adjustment to the range and production of a scale with operating frequencies are not required, you can do without a generator.

With the advent of transistors and integrated circuits, tube designs were forgotten for some time. Nowadays, radio amateurs are increasingly turning to vacuum tubes in their designs. Homemade VHF tube radio receiver can be assembled on one lamp. The circuit uses the super-regenerator principle. Such devices use a small number of radio components. They are highly sensitive. The disadvantage of super-regenerative receivers is noise in the speakers in the absence of a useful signal.

The VHF receiver is assembled on a 6Zh5P finger pentode. A bridge rectifier is used as a power source, providing 100-120 V DC voltage. All capacitors, except the transition capacitor, are ceramic. Coil L contains 4 turns of copper wire with a diameter of 1 mm. It is best to use silver-plated or tinned wire. Typically, lamp filaments are powered from an alternating voltage of 6.3 V, but in this case, to reduce the background alternating current, a constant voltage from a separate rectifier is used.

Complete circuit diagram of a VHF-FM receiver with a low-frequency amplifier. Depending on the type of output transformer, the device can use a high-impedance headphone or a 4-8 ohm speaker.

In the power supply circuit of the lamp grids there is an electrolytic capacitor of 50.0 uF at 200 V. A variable resistor in the control grid circuit of the output lamp regulates the volume of the signal.

Simple DIY tube receiver

A VHF receiver with frequency modulation can be made using a different design. This is a super-regenerative detector that is designed to receive radio stations in the range from 36 to 75 MHz. You can assemble a tube radio receiver with your own hands on one lamp 6Zh3P or 6Zh5P.

The circuit retains the fundamental designations of the original circuit. The signal is fed to the input of the low-frequency amplifier through a 5000 pF capacitor. Capacitor C1 is a tuning ceramic or air capacitor. Coils L1 and L2 are frameless. They are wound on mandrels with a diameter of 15 mm. L1 contains 7 turns of tinned copper wire with a diameter of 1.5 mm, and L2 contains 3 or 4 turns of the same wire. The number of turns is selected experimentally. The distance between the coils is determined during the setup of the circuit. To receive stations in the FM range (88-104 MHz), the number of turns of the L1 coil must be reduced to 4.

To do this, after turning on the power, by rotating the knob of the variable resistor R2, you need to achieve super-regeneration. This is a hissing sound in the speakers. Then, by rotating the tuning capacitor C1, you need to make sure that the effect is present throughout the entire range. Generation failures are eliminated by selecting inductor turns, changing capacitance C4 or resistance R1 and capacitor C2. Then a whip antenna (a piece of wire) is connected and the station is tuned in. When a signal appears, the hissing disappears and the radio station can be heard. You can change the frequency of the received range by moving apart and compressing the turns of coil L1.

The maximum permissible voltage at the anode of the radio lamp is 300 V. To reduce the background alternating current, it is better to supply power to the lamp filament from a separate rectifier. The finished and configured structure must be placed in a metal screen, as is done in industrial receivers.

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