Very encouraging and informative video, i love experimenting with valves

@lishaton

2 жыл бұрын

Glad you found it useful! At least you can see the circuit actually tried out with different valves on the video. Do have a go with it sometime. Don't forget that by making small changes to the coil, you can pick up anything from ordinary FM radio on 88-108MHz, thru' the aircraft band (108-136MHz) right up to and including the 2M amateur band on approx 144MHz.

Hello again and thanks for another excellent video. Best wishes from Western Australia Clare

@lishaton

8 ай бұрын

Many thanks for more positive feedback Clare!

I had quite good results with the EF91 as described on my cool386 website (which I notice the first one valve circuit was from). Having said that, a lot depends on the circuit configuration as well as the valve type used. A lot of published circuits I've found to be poor performers, with varying the B+ to adjust the regeneration giving less sensitivity than adjusting grid voltage. Also, having both ends of the tuned circuit floating causes difficulties with tuning capacitor mounting and hand capacitance.

@lishaton

9 ай бұрын

Having had a look at your website, it looks to me like you've 'been there - done that'! Interesting about the EF91, as I felt that theoretically, it should be fine, but I just wasn't prepared to fiddle around with the bias etc. in order to make it work better, just to compare it with the other valves on test. Yes, you can see the effects of hand capacitance with the simple circuit used for my video. The other circuit I used in my 'everyday' radio, (in the black chassis pictures) is completely stable in this area and is hardly ever retuned from one week to the next, and never drifts. (I use it most days) The same can be said with the much more complicated Practical Wireless circuit I talk about earlier on in the video. Thanks for the interesting feedback. (I must have a better look at your site too!)

@cool386vintagetechnology6

9 ай бұрын

@@lishaton I recognised the PW circuit as a Fremodyne; something I’ve also covered extensively on the site. It’s a good performer in terms of sound quality, since it was designed specifically to have a response curve suited to slope detecting wide band FM. However, it isn’t quite as sensitive as a good straight super-regen set.

Great job.

@lishaton

2 жыл бұрын

Thanks for the feedback! Are you going to try and make one yourself? At least you can see the results to expect with each different type of valve if you do :-)

Hello! Good work! 13:47 - in my opinion: it would be useful to have an impedance matching. The input impedance of a tube and LC circuit is quite high. I had an experiment with BJT super-regen and matching coil. I achieved an excellent sensitivity - roughly 2 microvolts on 50Ohms. I used an additional matching coil - the main coil had 20 turns, and an additional - only 2 turns. The second important thing - is the waveform of quenching (signal an oscilloscope in a 4nF capacitor). You can connect in series a variable resistor. To blocking RF in this case connect a 100 picoFarad capacitor after RFC and ground.

@lishaton

11 ай бұрын

Some excellent suggestions! However, for this particular project, the plan was to keep it as 'simple' as possible, hence when we tried a couple of the sample valves, they didn't work particularly well (in this circuit) Clearly things would have been improved had we made small component and circuit alterations like those you've just suggested. It still surprises me just how well something like this can actually work!

@thomasvandevelde8157

11 ай бұрын

@andrewandrosow4797 Did you also build the Charles Kitchin Receiver? I build it using tubes instead of J-FETs and got it to run on 2 meters band. Just changed the circuitry for an EC92/6AB4 in the detector stage. Thanks to that Quench-Waveshape system he introduced, I could easily follow the local 2 meter repeater without an external antenna! Did you demodulate Narrowband FM succesfully with your version Sir? Regards, Thomas PS. Impedance matching is indeed very important with a super-regenerative detector, it's after all still a regenerative detector forced beyond it's comfort-zone! Inductive coupling is better than capacitive, and it must be variable.

@thomasvandevelde8157

11 ай бұрын

@@lishaton Yeah they're a small miracle these things, they kept me fascinated for decades now, trying to tame them for good. I still remember my first DIY transceiver for 11m band, build around a 6J6.

@andrewandrosow4797

11 ай бұрын

@@thomasvandevelde8157 Hello! I made a receiver that consisted from two BJT. Emitters was connected together, the base one and collector two was cinnected to ground.The base two and the collector one was connected to "hot" side of LC tuning circut (a cold side of a LC circuit connected to the ground). The emitters was connected through an inductor (5-20uH) to a small capacitor (200pF) to blocking HF on the ground. This point is very important - you get an audio signal from the one - let's assume that it is a point with a title "CP1". To CP1 was connected a variable resistor 270KOhms that connected to positve/negative (it depends a type of transistor) bus of a battery. Now we went to the essential circuit in our receiver - control mode circuit.This citlrcut consists from a capacitor (several nanoFarads) that connect in series with a variable resistor (several kiloOhms) between CP1 and ground.When a resistance is maximal - the receiver can generating continously without flashing and superregenerative noise: in a speaker can be silence. When you change this resistor's impedance- you change a quench waveform: from triangle or pulse to smooth (like sinewave). The output impedance of this receiver is quite heigh - 100..300 KiloOhms: it woult be correct to reduce noise to use tube or jfet audio amplifier. I made experiments with this receiver and I received FM broadcast stations with specifing overdrive distortions - because wideband of this recriver was quite small. The quench waveform in CP1 was quite smooth - and the superregenerative noise in speaker was less intensive and brown. Unfortunately I have a very small experience in tube electronics - I only made a regenerative MW receiver (using a triode) when I learnd in a school. This tube regenerator worked very vell - moreover it received FM stations with very clear sound (I thought so in my young years) . In my oppinion - you can achieve the same effect in tube receiver: the grid leak circuit can be more complex: for example 100KOhm resistor in parallel with a small RF capacitor (47pF) and also in parallel RC circuit (4.7nF, 10kOhm variable). I have not done the experiment with tube - it's my own opinion.

@thomasvandevelde8157

10 ай бұрын

@@andrewandrosow4797 I did use a complex grid-leak system once, consisting of a 300k + 2,5k in series with a 220pF capacitor. This was the timing circuit for the quench-frequency too (as is the case with many superregens using transistors too) and this had a huge impact on selectivity yes. The noise indeed changes, and becomes less "agressive" sounding, so to speak. It worked only with very high gain tubes, wouldn't use it on an 955 Acorn for example. But the EC92 did just fine in this circuit. And I'll tell you one thing: at higher frequencies, the input-impedance of tubes drops véry rapidly. For example the "Locomotive" of Tube-Era TVs, the EF80 pentode, has an input impedance of 10 to 15kOhms at 50 MHz! The CV408 frame-grid triode (the first for that matter, at least with an 7-pin base) has about 20kOhms at 45 MHz, so it starts dropping to the point you've got a few kOhms at 100 MHz. It's not much difference with a BJT at UHF-frequencies even. Also, the Q-factor and hence impedance of your LC-circuits drops so far by 100 MHz, it's just a few kOhms too in many cases. So, the higher in frequency you go, the more things get "equalized" so to speak. I'd send you an email if interested, but could not find any emailadres on KZread here? Perhaps I looked over it, it's possible. I'm not a digital proficient person 🙂

Muchas gracias por el proyecto. Intentare hacerlo, y despues comentare como salio. Saludos cordiales .Dany - LU2EAO

@lishaton

3 жыл бұрын

Espero que funcione bien. ¡Por favor déjanos saber! Gracias por el comentario. Chris

Ah the good old vr137

@lishaton

Жыл бұрын

Just sits there and oscillates away, hour after hour, just under 100MHz :-)

@thomasvandevelde8157

11 ай бұрын

@@lishaton Sad it has one of those impossible 9-pin EF50 bases, you don't find those around here. Did the British ever introduce the "standard" 8-pin Loctals at one point? Or they just went straight to Rimlocks and Novals?

@lishaton

10 ай бұрын

I believe all types of bases must have been supported at some point in the UK, even for just a short time. I have a large number of ex. equipment types here which must encompass many of them.

Neat! Thank you for sharing! Curios, what would increase the ability to to pick up weak stations? I am in a rental, so can't go crazy with an antenna and some reason FM stations are hard to pull in.

@lishaton

Жыл бұрын

To be honest, without significant changes to the circuit, I don't believe it would be easy matter to improve the set in this particular area. With our own situation, where the set was demonstrated for the video, I think it is surprising just how well it worked with just one metre of 'throw out' wire in a semi-basement situation combined to a 'not-very-good' signal strength area. But of course, you can see how different the 'Acorn' valves were when compared to the other types tested. Maybe worth trying other types? You'd need an additional coil at the front end to use a dipole which might improve matters too. Aerial positioning, even with a simple length of wire makes a BIG difference to signal strength. It is possible that you might find that an air-spaced variable cap might be slightly better too if you're not already using one?? Incidentally, I have recently done a spot of experimentation with a slightly different super-regen circuit with a tapped coil and a dual tuning cap, combined with a second valve as an RF amp, but have found this gave little significant improvement.

@adrielrowley

Жыл бұрын

@@lishaton , thank you for the reply. Mind me asking what happened to part two? Or would you say the 6SL7 be the valve of choice? So the gain of the tube has no impact on sensitivity? When say dipole, you mean a T shaped wire or a manufactured antenna with a coax cable? Were would one find the specifications on the additional coil? Not really any aerial positioning options, north is the only side exposed, to the about west-northwest is where local FM comes from, so probably the better of the three anyway. To be clear, I have never built a piece of equipment. So no, don't have an air-spaced variable capacitor. My goal is build a tube amplifier and thought the simplicity of this unit be a good start, plus, be fun to see how compares with a solid state tuner (does better than anything had before, however, sometimes gets finicky).

@lishaton

Жыл бұрын

Sorry, I've literally only just sen this! To answer your questions one by one: My Mk2 VHF / FM version was tried with both the VR137 and the Acorn 9003. I didn't bother with any others having tried them for the demo you've seen. The additional RF stage using another acorn was simply not worth the bother as it really made little - if any difference. Yes, by 'dipole' I meant a coaxial lead which ended up with either a T shaped pair of wires, or solid conductors. Check the dimensions. About 1 1/2 metres for a dipole split in half and should be ok for FM radio. The coupling coil will be just like most other aerial coupling coils. The smaller coil should be something like 18swg self-supporting with about 1 1/2 turns made on a 3/8" diameter former. Position this near (in line) with another self-supporting coil using the same wire on a 1/2" diameter former. You could try putting a low value trimmer across it of about 20pF to allow for a bit of tweaking. The two ends of the smaller coil will go to your coax. of course. Your chosen signals determin whether the dipole is positioned vertically or horizontal. Your last comment about a valve amp. suggests to me that you should try for a circuit using a single small triode-pentode valve like an ECL80/82/86 etc. I think you will be pleasantly surprised just how good one is. Food for thought...Maybe I'll build one in a day or two for another project :-)

@lishaton

Жыл бұрын

Sorry, missed the bit about the second part of the coil. Approx. 4 & 1/2 turns self supporting made on a 1/2" former. (In line with the 1 & 1/2 turn going to the dipole.)

@adrielrowley

Жыл бұрын

@@lishaton , I myself been unwell. Interesting you mention the ECL86, I have taken a fancy to it, however, was unsure about proceeding forward (crickets on the forum); been almost a week. Just put an offer on a pair of PCB boards. Thank you. 😀 By the way, to challenge myself, did try and build this one valve in LTSpice, however, wasn't sure how to model the antenna input signal, nor seems anyone else. Also, LTSpice doesn't seem to like pots either and again been a couple weeks of no reply. Typical for me to think so unique (I am Autistic) no one can help with my ideas. Bet no one has ever modeled a receiver in LTSpice.

Hello, I am experimenting with a similar circuit in which I need a transformer of 600 ohm primary and 10K secondary, could you advise me how to get it or what type of transformer would work for me?

@lishaton

Жыл бұрын

Good question! Not something that one finds easily these days. In order to end up with a 10K secondary, I can't think of anything aside from an EHT / high voltage transformer, though I doubt if it will have a 600 ohm primary. What is it actually needed for? Maybe it is possible to alter the circuit, or substitute something else?

I remember experimenting with similar circuit but with ECC85. It did receive local station very well. I live 10 miles away from the 120 kW transmitter so that signal is particularly strong in my house. Good audio quality but very sensitive to environment - moving hand, changing temperature, voltage etc - everything caused frequency drift. If properly assembled on chassis, with respect to the principles of HF circuits, it might have chance to work.

@lishaton

Жыл бұрын

I agree with all you say. However, the one with the black chassis in the picture is used most days and seems quite immune to hand capacity effects etc. as I feel it has been built to a reasonable standard (?) I'm not sure where our nearest transmitter is, but I think it's quite long distance as we use a chimney FM aerial for our Quad FM tuner. Whilst the super regen set never seem to need retuning, even after switch on (i.e. it doesn't seem to drift at all) the signal does vary in strength from day to day, I guess due to atmospherics etc.

You need a pop filter when you are recording your voice overs.

@lishaton

Жыл бұрын

I use one on my hand held mike, but there's not one on the camera for all the rest. I know it is not too good for some of the soundtrack!