gemeinsch: VE301W; Volksempfänger: Volume control?

Well, I'm making some steps forward and some backward with my VE-301W.  I replaced all of the capacitors and applied power.  The first thing I discovered is that the power switch is no good.  I had to bridge it with a jumper to get power to the radio.  Next I found that my RGN-354 tube that I spent so much time on carefully repairing didn't work.  It emitted a pale blue glow and created no B+. I guess it was gassy.  Fortunately, a kind member of RMorg had sent me a spare, so I used that.

Now at least I got normal B+ and started hearing sound from the speaker.  Next, when I tried turning the regeneration condensor, the Bakelite disc that the metal shaft connects to snapped in two.  So now I can't turn that control.  Arrgh!  And finally, it appears that the RES-164 output tube is also bad.  The voltage at the speaker is about 50 v. low.  Tapping the tube produces lots of loud crackling and causes the voltage to jump up to the correct value.  About the only good thing is that I was able to pick up a  few stations.  But I'm about ready to give up on this radio.  I'm really disappointed with all the problems it has.

One possibly silly question though - where on earth is the volume control?  This radio appears to have only one volume: loud.

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Right,  there is usually no special control member for volume. In all such simple TRF radios having only one tuned circuit You have to fiddle a bit.

You can adjust by selecting a suitable antenna jack (coarse) and the reaction (fine). 
You have to find a balance between selectivity and volume (sensitivity/signal strength).

This method is not limited to VEs, but rather common to this type of circuitry. If You ever tried to tune a reaction receiver from the early 1920's like a Crosley V or an RCA RC or Radiola Sr., or any Reinartz circuit, You know what I mean. These oldies even had a third member to influence: the filament control... but no distinct volume control.

Don't give up, You will make it !

Good luck,
KoBi 

 PS: VE301dyn and DKE use variable antenna coupling for the purpose.

This article was edited 17.May.09 19:36 by Konrad Birkner .

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Michelle, I have been enjoying your restoration progress, and have been learning from every dificulty you have encountered.

Sometimes a radio insists on teaching you much more than you planned to learn from it. It can be frustrating, but you will come out all the wiser.

Have had quite a few radios take me by the tail, in a spin. But persistence has usually won the day.

Best regards, and keep up the battle.

-Joe

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Thank you very much to Konrad and Joe for the encouragement.  I went back to this and applied a few dabs of super glue to the broken shaft connection of the regeneration capacitor, letting it dry overnight.  I wasn't very optimistic but to my surprise the repair seems to have worked quite well.  The super glue bonded  well to both the metal shaft and the bakelite.  However, the shaft was still hard to turn.  That may be why it broke in the first place.  I used compressed air to blow out the capacitor, then squirted some tuner cleaner in it.  That didn't help much.  In desperation, I applied a few small drops of light oil to the plates and let that penetrate for a few minutes.  That helped a lot.  I can now turn the shaft easily even without the knob on it.

I then contemplated drilling out the rivets in the power switch to see what was wrong in there, but I found an early 60's vintage SPST toggle switch in my junk box that fits perfectly and doesn't look too bad, so I just replaced the original switch with that.  I'm still keeping the original with the radio though so that I can look into it some day (or its next owner can).   The AC line cord is also in bad shape and the insulation is cracking.  I will go out and get a new fabric covered replacement cord this week and  replace that too.

That just leaves the RES-164 tube.  I put in a want ad here but no replies so far.  I haven't found one here in the US either so far.  I've seen several for sale on the ebay.de site but the sellers won't ship to the US.   Hopefully something will turn up.  So for the time being, this one is going to the waiting room while I move on to my next project - a Philco 39-116 console with the Mystery Control wireless remote.

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Dear Michele,

you can try to repair the old toggle switch if the problem is due to oxidation or to hardened grease.
 
Make a little hole, about 1.5mm, in one of the largest sides of the insulating body, halfway from the center line and the edge. Pay attention to not penetrate too deep in the switch to avoid damages to parts inside: you can use a suitable spacer over the drill bit. Insert a spray contact cleaner through the hole, while operating the switch lever; repeat this operation several times, since very few cleaner may penetrate inside each time. Check the contact resistance with an ohmmeter for a value not greater than 0.2 ohms.

When the switch works again, you can use a drop of silicone sealant to close the hole.

About the VE301W, it can be the right set for you to experiment and learn about the operation of reaction receivers, when the reaction control was used to have the best whisper to whistle ratio. Once the radio has been returned to its original operation, it is better to leave it non-operating, unless you want to generate such an electromagnetic pollution, as the pollution from the disaster of the Exxon Valdez.
 

Regards, Emilio

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Hi Emilio,

What exactly does this radio do when it is working, other than receive?

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Dear Omer,

I am not the right person to explain how a regenerative receiver works and I have no experience with this model. I can just give a generic evaluation of the detecting technique used inside. Regenerative receivers gained some popularity because of their low tube count: a single triode was used as detector, giving gain enough to directly drive the output stage. This was made possible by the positive feedback used in the RF/detector stage.

The Q of the tuned circuit and the sensitivity of the detector depend upon the regeneration, or reaction, introduced. The radio does not have a volume control because the gain is controlled by the feedback control, a 180pF variable capacitor in this case. The proper feedback level varies with the strength of the tuned station. The highest sensitivity is reached just before the circuit starts to oscillate and this is a very critical condition. This radio uses an even more critical circuit, with capacitive feedback, and the same hands of the operator may have effect on the coupling.
 
The search of a new station and all the tuning steps in these radios, however, are usually performed keeping the regeneration as high as possible, to easily capture weak signals. The squeaks and the whistles that come out from the speaker, while moving coarse and fine tuning, indicate the presence of oscillations. When tuning, and until a steady point of maximum useful sensitivity is reached, the detector triode oscillates and strong signals are radiated all around. You can easily verify this behavior with a simple transistor radio tuned on the same band.

Regards, Emilio

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So Emilio,  with this kind of radio,  if you are listening to a station, everybody else around you gets to listen what you are listening on their radio, even though they are not tuned in to the station you are listening to?

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No, the reception of other radios in the vicinity is not influenced when the regenerative receiver has already been properly tuned. The radiation problem just arises during the tuning operations or when too much feedback is left. Other detectors, as the superregenerative or the heterodyne ones, give RF pollution even during normal listening, but this subject is not related to the above model. And I repeat, I am not the right person to give details about the operation of the several detector circuits used in the past. I was only joking, while remembering my first experiences with regenerative circuits in the late ‘950s.

Regards, Emilio

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Thanks for the idea on the volume control, Emilio.  I had already tried squirting tuner cleaner in the existing openings, to no avail.  I noticed that by shaking the switch, I could cause it to make contact temporarily, so there is definitely something mechanical broken inside.

On the plus side, I suddenly got the idea to check the pins of the RES-164 and sure enough, one of them had a cold solder joint.  I could actually see the tip of the disconnected wire inside the pin.  A quick touch of the soldering iron and I was in business!  So the tube is actually OK and the radio is now performing quite well.  The oil I squirted into the regeneration capacitor did not hurt it and it is now working well too.

It still needs a new line cord, some cabinet work, and maybe a correct speaker if I can find one.  (Someone long ago replaced the original speaker with a small 5" speaker).  But this was a good exercise before moving on to my VE-301 GW, VE-301 dyn, and the big DAF-1011.

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Michelle,

Considering that you are establishing some expertise on these radios, could you describe what listening is like?

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Interesting question, Omer.  If you mean the sound quality, I'm afraid this particular VE-301W is not a good example because the original speaker was replaced with a much smaller one at some point in the past.  I'd put it to be about the same as a small 40's vintage AA-5 table radio, in other words not very good (though it gets plenty loud!).  My other currently working radio of this era is a DKE-38 which is all original and I'd say that one sounds surprisingly good.   I would have thought there would not be much bass reproduction, but there is certainly some there.

Keep in mind that I like to listen to period music appropriate for the radio.  So I listen to 30's and 40's swing music on my Crosley Prestotune, 50's rock & roll on my 1950 RCA X-551, and military marches on the DKE-38.  None of these sources are particularly hi-fi to begin with so it's difficult to give a good description of the contribution made by the radio to the sound.

I do have another VE-301 with the original speaker that I will be working on later.  It will be interesting to compare that one's sound to both the DKE and the DAF-1011.

If by "what listening is like" you mean the subjective experience of listening, I'd say it's pretty cool.  Being able to hear music exactly the way people did 50, 60, or 70 years ago is sort of like having your own time machine.

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Perhaps, I should rephrase the question a little differently.

How does this radio behave, if you try to DX for weaker stations, and how does it handle very strong stations?

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Ah - I see now!  Unfortunately I can't answer that question.  I don't really have a good long wire antenna set up since the Great Ice Storm of 91 blew it down 18 years ago.  I can get half a dozen local stations just fine using just 6 feet of wire and a solid ground connection down in the basement.  The ground seems to be essential - without it, I get nothing.

However, this is actually a very interesting question to try and answer from a historical standpoint, since the assertion is often made that the design of the VE-301 and DKE-38 was deliberately crippled to prevent Germans from listening to foreign broadcasts.  However, I have never seen any numbers supporting that claim.  Though it might in fact be plausible (consider the infamous "Denke Daran" sticker).

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Dear Omer,

I am not sure if your question refers to this specific model or to the large family of Volksempfänger sets. These radios were promoted for propaganda purposes and had to receive just the local station; in Italy we had the Balilla, a TRF reflex circuit, and some other unified models. The primary target was a very low sales price and this requirement asked for severe compromises in sensitivity and other performances.

If the interest is generic about these popular radio sets, it would be better to start a new thread dedicated to compare their solutions and their performances.
 

Regards, Emilio

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For all Volksempfaenger the specification said, that everywhere in Germany a local station must be heard. That was achieved for the MW (BC, on the old sets called K for kurz in contrary to long wave, it is not shortwave!). Only for LW (longwave) the coverage was something about 90 % or so. And the models had to be completely standardised, and every manufacturer had to provide a certain quote.

There was never such a silly idea to prevent foreign stations, since that is impossible (and a shame for every radio engineer)! Dont forget that before outbreak of WW2 many of the better German radios were advertised  for "Europaempfang". That would not go together. Only during WW2 it was strictly forbidden to listen to foreign stations.

Such an assertion as mentioned is simply nonsens, sorry.
The only way would have been fixed tuning (even cheaper!).

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Hi,

attached is an example of the famous italian song produced from a regenerative receiver equiped by a magnetic 2 poles system. This is very similar to VE301 and similar "empfangers". So, it sounds this way :) ==> Link

Regards

Viktor Cingel, Slovakia

This article was edited 25.May.09 06:43 by Wolfgang Bauer .

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Hi all,

I wish to underline that the quality of the sound in regenerative receivers was influenced not only by the signal strength but also by the skill of the operator when performing the tuning operations. The regeneration control influenced the effective Q of the resonant circuit, changing the selectivity: the higher the regeneration, the narrower the bandwidth. Another known problem arose when the regeneration was set very close to a point where oscillations occasionally built up. In these cases, heterodyne with any present signal gave annoying whistles.

Best regards, Emilio

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Dear Victor,

let me emphasize that Your example is anything else but representative for a VE or even a DKE! Provided the speaker and the power tube are ok, then the operator was not doing his best or the environment was RF polluted. Your soundtrack is not fair, sorry!

Anyway DXing was never in the scope of such receivers. Some modest sound quality requires a certain field strength and the absence of jamming signals in the close vicinity of the frequency.That was quite achievable in the days when those receivers were specified, designed and produced. Often an additional suppressor circuit (Sperrkreis) improved the situation.

Similar fate is happening to multi tube sets of the earlier 1920's. They had been made when stations did not yet deliver hundreds of kilowatts!  Electrical screening was not a must. Nowadays these old radios are hopelessly overdriven by spurious signals.

Regards,
KoBi

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When I have played with my 1920's sets, I have found that it is easiest to find a station while the radio is oscillating with just enough excess regeneration. This makes weak stations that would be missed, very easy to identify by the characteristic whistle, or beat frequency, that they produce.

Once the station is identified by the whistle, I adjust the tuning control for the lowest possible frequency whistle, or beat.Then I reduce the regeneration until the beat disappears and clear sound emerges.

You would be amazed  with how much DX listening you can do this way.

Some 1920's sets that were not marketed as regenerative sets, will oscillate like a regenerative set when their gain or filament voltages are set at maximum. So the beat method can be used with these sets too.

Regards,

-Joe

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Hi Joe, and to whom it may concern.

Sorry, but that is exactly what one should not do. It is an easy way, I admit, but it is rather mean to emit such electromagnetic pollution.

It is very unpleasant if such ruthless whistling from an eager DXer in the neighborhood is disturbing my concert or any other program.

Please do not exercise such unkind practise. In particular with single circuit TRF, where the oscillation is coupling into the antenna.
If there is an RF stage first and reaction acting for the second (audion) stage, the problem is almost negligible. Same is valid for oscillating three-dialers etc.

Sorry again for my harsh words, but I remember to have suffered often from such interferences. That may explain my temper...

Thanks,
Kobi

This article was edited 29.May.09 09:13 by Konrad Birkner .

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Hi Konrad, I have done this beat tuning with my 5 tube Silvertone/Trav-ler. This radio has a single tuned loop, and fixed RF transformers in it's 2 RF stages. This radio was not intended to be regenerative, but it will oscillate if run at full filament voltage or with the forward grid bias volume attenuation control set for highest gain. This set has no neutralization, so it is not surprising that it will oscillate fairly easily.

Next time I do this I will sniff for interference with a pocket AM radio, and see how far I have to walk away to stop the noise. If the noise stops a few feet away, this is probably OK. I also don't use an outside antenna with this radio. I use the built-in loop, In order to supplement the sensitivity of this loop, I made a loop around the window that is next to the radio, and tune it to the same station. The loop is made from one loop of CAT5 Ethernet cable with 5 solid conductors, and is just visible at the far right edge of the photo. The five condutors of the CAT5 Ethernet cable are wired in series at the ends of the cable to make a loop that is about 2mX1m with 5 turns. I use a 1920's tuning cap to tune in the window loop.

It will be useful to know if I can cause interference into an adjacent room. It may be difficult to make more noise than nature, or more than modern computers, switching power supplies and light dimmers, once I am more than a few feet away.

If you use regeneration to tune in your radio, check how far your interference reaches. You may be OK, or you may not be.

Update May 31 2009: I started a new thread on the topic radiated RF interference.

Regards,

-Joe

This article was edited 31.May.09 08:16 by Joe Sousa .

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As I said before, for a short while I used some regenerative radio sets around 1960. The search of weak stations, other than the local one, could be better performed while the detector was oscillating, paying attention to the whistles when moving the variable capacitor. RF radiating in these operations was enough to jam other radios in the building, even those operating at different floors. Jammed radios were silenced at all when they were tuned on weak stations. The RF power of the oscillating detector can be in the order of some hundreds milliwatts.

The true problem is that RF coupling can take place through unpredictable paths. A big loop antenna can be the most obvious way to radiate RF oscillations. But more or less powerful e.m. waves radiate all around from the tuning circuit through the wooden cabinet, also coupling to the power line. The simple aluminum shield around the tuning coil, when present, is not enough to prevent e.m. pollution.

The problem of radiation from regenerative detectors was so severe that virtually no military receiver used these circuits, to prevent localization by enemy. And military receivers were usually housed in heavy shielding cabinets.

The regenerative receivers are fascinating relics from the past, with their sensitivity, exceptionally high for their few tube architectures. But today owners should carefully self-limit their use. I believe that no regenerative radio complies with today applicable EMI rules.

Best regards, Emilio
 

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Just out of curiousity, would this "jamming" effect take place on the FM (UKW) bands as well?

Otherwise, I don't think that there are as many people out there, that listen to the broadcast band (MW) in this day and age.

My real problem is, hearing data transfer interference on normal stereo speakers (that are not sheilded) from GSM enabled cell phones.

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Dear Omer,

The first answer is reasonably ‘no’. The high Q LC circuit grants the generation of clean sinusoidal waves, containing virtually no harmonic in the FM band. Of course this is not absolutely true during transitory, as when the tuning control is moved and beatings occur with incoming signals.

The GSM phones uses fast digital pulses and their harmonic contents are so high to interfere with any electronic equipment in the vicinity. The problem may be particularly severe with avionics or life support equipment and sometimes you are asked to switch off your mobile phone or your PC.

It is hard to say how much and where old electronic equipment radiate. Some manufacturers took precautions against interference, other did not care of the problem at all. Every different set could radiate more or less, with peaks in some bands, depending upon several factors. The measure can be performed by qualified laboratories inside anechoic chambers with expensive equipment. Allowed limits however may vary from one place to another.

Regardless of how many people are listening to any particular band, my was just a warning about the possible interference’s coming from this kind of receivers. It can be wise to limit the use of these radio sets to prevent any problem. If you want, you can easy sniff the radiation over common bands with a transistor radio, as suggested here: www.radiomuseum.org/forum/a_few_rf_interference_measurements.html.

Regards, Emilio
 

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Hi Emilio!

Thank you for your explanation about the FM bands.

However, to understand what I'm talking about, regarding cell phones, place an Apple IPhone next to one of your stereo speakers and see what happens when you receive a text message, or when someone is calling.  It sounds like a teletype signal going crazy, through the stereo speakers!

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If you hear interference from cell phones in your speaker this normally will be a simple detection effect of the transmitted RF. The RF pulses are rectified by transistor's emitter - base diodes, provided the mobile phone is nearby. This can be checked easily if a simple AF amplifier is used. 

Regards, Dietmar

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