TheRadioBoard

I have been working on building a vintage regen 1920s style single pre 1930 tube. Not an easy task. When I get it to work it is too unstable for ham radio use. When I fix stablity it doesnt want to regen. I can get it to operate some with a 71A tube but it pretty quiet with a o1. i have tried cross tickler pot with wiper feeding the plate and got it to work but hand capacity was terrible. I tried switching the cap rotor to ground and the fixed to floating. It didnt like that. Wouldnt run. I eventuallly got it going but it was too weak to be useful. I tried throttle cap today I tried conventional pot control. I have had three different coil sets in it. Today i took it back to the shop for a complete teardown and redesign. i think some of my leads are too long. Maybe the whole layout is too big. I have a commercially made set from pre 1920s regen with a 0A tube. it uses inductive coupling but swinging the spacing between the tunes coil and the tickler and the antenna. It works pretty good too. My radiola also has a varicoupler deal which while not the same is similar idea. I checked a lot of things and tried a lot of stuff. but it just isnt going to be the radio I need.
My 6sl7 twinplex works fine for qsos. i figured this would be similar just queter wirgh no designatedf audio section. It wasnt bad when i had it going with the 71A but as a communcations radio it was useless. I have searched for a circuit and havent found anything that turned my crank yet. I have decided though that very early tubes and a different kettle of fish than stuff made after 1930 for instance. I wanted a all pre 1929 station. I have the tx made and working. I wanted a companion recvr for it before going on the air. Any early circuit diagrams pre 1929 for a single triode regen would be of interest to me. Any experience one has from using these tubes would be of interest also.
Don VE3LYX

uhm, I suspect your tube is not 100% ok,
either that or the layout as you say,
My single tube 01 work ok for catching CW up as high as 40m without much trouble.
to get there i think i did 6-7 designs, in the end had to build the radio about same I would a DX SW crystalset, that is really thinking how things interact and realize that even a dirty capacitor or wrong matching to the phones can kill the thing.

Yes that is how I think too. Build a crystal set tank circuit. first. then a feed for ant cap. Install a grid leak assembly were the diode would go. and that goes to the grid. the other end to the cathode /filiment. Tickler was next. approx 1/3 turns of tuning coil. Phase right so polarity is right. Control plate voltage (it varied nicely , smoothly from nothing to 110 volts.) 2000 ohm phones. Brandes originals I have two sets and swapped them from my other regen. No difference on either set. Check cap several times . Good contact no dead spots. I first built it with a matching set of coils from my TNT tx. Didnt really like that. I built a smaller coil 1 1/4 inches . It worked on that with a 5 meg gridleak but hand cap was a big deal i did however run it for a hour copying cw from W1AW . I couldnt move though or I lost the signal. So I thought since my hand bothers it mostly at the knob I will gound the knob(roto) and float the fixed plates. It is a vintage cap and had phoenelic endplates so it wasnt a problem. Just to be absolutely sure at one point I insuated it from the front panel anyway in case something I couldnt see was touching. I could track it on my other receiver so I knew the circuit was tuning but it would no longer regen. I played with coils , phasing types of regen control etc etc. everyday for two weeks. Yesterday I put it back to floating rotor and had it working for a few minutes. totally unstableand not as good evenas before. I think because I was trying to build a matching set to my tnt tx I built it far too big and the leads were far too long allowing ground loops and extra effects. My other set which works so well I prefer it for cw over a communications reciver. I built it snuggled up tight with minimum lead lengths. It is also a more modern tube. I want a 20s style vintage regen so I am committed to getting this working. For me early schematics have not been easily forth coming for single triode sets. I have searched every single day of two weeks. What exactly did early hams use I wonder? What kind of tickler control did you use? You could be right about the tube. I have several options and have tried them all. the 71A was the best substitute.
Don VE3LYX

Hi, Don,
The 1935 Shortwave Manual has a circuit using a single 32. There is also one using a 12A7, but that may be a newer tube than you are looking for. If you are interested in either one and don't have a copy, PM me and I will scan the articles and email them to you.
73, Randy K9ANF

'99 types are "reputably" better for use at higher frequencies than the average '01A if you want to use a really early tube. No experience myself.

BTW, exray's "Grebe CR-18" clone works to 17meters if I interpret the text correctly, using a "special" '01A.
http://www.sparkbench.com/homebrew/grebe/cr18.html

I havew a 30s style regen already and it works absolutely wonderful. ("Ham Radio After Dark". You tube) I have built a 1920s style TNT transmitter using a UX245 and want a matching recver. I dont put my vintage tx on the air unless I can use a similar vintage rx so i wanted to build a 1920s set including the tube. I was hoping for a single tube , single triode set. I have a single triode commercially made set pre 1920s but it BCb only and uses inductive coupling only for regen and antenna control. The single triode circuits are hard for me to find. I think I will take a wack at this one agian tomorrow shortiening up the leads and reinstalling the second coil pack as it worked the best. Still if anyone has a single triode 1920s schematic I would be happy to see it.
Don VE3LYX

I guess exray's is a 1 tuber if you don't add the audio amp stage.

Hi Golf. Yep, I guess so but it may behave differently going directly to fones instead of the audio transformer. As I mentioned to Don via another forum I'm kinda hard of hearing so an audio stage is a must for me.

And yes, that clone CR-18 would tune almost to 18 Mcs although it really wasn't made to do that. Tuning is waaay too touchy up there at the end of its range to be fully useful even for tuning SWBC stations.

Speaking of limits...I've heard mention of the old reliable Reinartz circuit used all the way up to 50 Mcs with an 01A! Involves un-basing the tube and some other slight of hand. I'm glad I have no compulsion to tackle something like that!

I got it working! The revamp payed off. It works at the moment only in the centre of the cap travel and is dead at both ends. I think my regen cap control has too many plates for good control but it does work and has decent volume. First signal i had was CHU time signal which seems appropriote to me. I played with gridleaks till I was happy. Wound up with a 6.1 meg/150 pf asssembly. B voltage optimized at 72. Phones drop the plate voltage a lot. I played with 5 different tubes. I found my UX201A just a bit better than the rest so it is in. Spent about 1 1/2 SWL ing last night. It is a bit high in tuning freq but that is easily fixed. Regen comes on too quick. Will try a different cap today and then if necessary solder two of the tickler windings together to reduce effect (cause that is reversable if it doesnt help) Not many parts in this radio. Tis amazing it works. volume is "sufficient"
Don VE3LYX

Got it working into 40M CW band which is what I built it for.
Don VE3LYX

Hi, you optimized the voltage at 72? Did you try voltages in the 20's where a lot of regens like to be? Wonder if using an audio transformer would help, partially in isolating the 'phones from the B+ voltage and maybe a bit in less body capacity to the set. Front of the back panel has a grounded shield to cut hand capacity? Mount tuning/regen caps towards the back and use extended plastic shafts to the panel? To be more true to the 20's the shafts could be 1/4" wooden dowels. Just a few $0.02 ideas! Sounds like a fun set.

Oops: haven't been here for a while: just saw yout comments in another post about not using a transformer. Just forget that part! I actually agree with you and have built radios since the 1950's with B+ going right through the 'phones, starting with my first Trimm Dependable.

I have rebuilt this thing several times and finally about an hour ago got it working as I expect.
I have no problem using a transformer for a speaker or lower impedence fones I just dont accept the idea that it is dangerous not to. Rather than run off about it I took an afternoon and measured actual voltages and realized how absolutley foolish such dribble is.
Anyway back to the 201. I tried a pot accross the tickler , a pot accross the b supplys feeding the plate on the wiper. a pot using only wiper and input in the tickler line. a variable cap and a variable inductive coupling. Most I got working but not to my satsifaction. I took off the coil and removed the 4 turn tickler. it has been five as well . I had been playing with the cap values on the throttle cap and adding 400 pfs made it better but not enuf. I rewound the tickler about 3/8+ inch away but wound 8 turns and a bit. i figured if it needed more cap then more L would also do the trick. I hit it right on believe it or not. Now I need no extra cap on the throttle cap and it is never full either way. Set works not bad now but it was mid afternoon which is hardly the hot time for 40M. I will try it tonite. It appears to be optimized from CHU s signal just below the band to the end of cap travel which is past even the phone section of the band. All I want is the cw portion and I think I am good now. I was able to couple the antenna pretty good and still get regen. I have 52 volts on the plate. circuit downwind of the fones and resistor. I have - 9v on the grid. I can run filiment volts down very low and it still works . That affects grid bias too with a direct heated tube. I think the tube likes the lower bias (around 7 volts with the reduced heater voltage) so it gains what it would have lost from reduced heat. The grid leak is 218pfs 3.9 megs. I have tried a 1/2 dozen . This is the best so far. I think 3 megs would be ideal but I dont have such an animal so this is it. (for now. ) Volume is decent. Should be enuf. I can work below osc or above so AM and CW are copyable. It is Ok I believe for to work with my tnt. It is nowhere near as sensitive as my 30s style regen but it is usable. I suspect in 1920s that was about as good as it got.
B volts.
I had it as low as 45 input . It was still working but lost a lot of volume. I realize folks run their sets on very low vltage but I would question are they single triode sets or one stage if you will. I suspect they are at least twin triode tubes. I am behind the 8 ball here with a 1925 tube and no audio stage. It was not easy. I did get a lot of good info from Herr Scmarders pages. I read the blurb on reflex and regen and it helped me figure out the solution. Thanks Dave. (vielendank)
I was thinking I had too much coupling but in fact I was not getting enuf feedback, This I beleive is due to the difference between a 20s tube and a 30s or "modern" tube. This has been good for me.
Re hand cap. I have only one spot that is bad.
I am using a vintage variable cap with a through shaft running a trim cap at the rear. It is when I squeeze that little knob in the centre that I get the problem in any amount. I think I will find some plastic and machine up a nonmetalic shaft. Or make an offest handle to run the cap so my fingers are not squeezing it.
Don VE3LYX

I've found that 01A tubes seem to like higher B voltages than most tubes used for regens. I think this has to do with the fact that the 01A is an early low mu tube. 45 volts usually seems to work with them, and I have seen 54 volts work well, too. If you use a B voltage in the 20's you may have to add turns to your tickler until you reach the point where moving the tickler affects the tuning, before you can get it to break into oscillation. 72 volts seems a bit high, but if it works well for Don's set, then that's fine, I think.

Norman
KA1GUK

Since I use 9 volts just snapped together I can do a lot of different B voltage experiments.
This tube hasa hefty appitite for heater batteries.I use a rechargable but what will run my 6SL7 regen for hours will power this one about an hour.
Set gets quieter when heater voltage starts to drop off below 4.5v. Still I copied F5IN calling CQ DX tonite so i guess I have a working radio. I wish I had power and a 40M ant for my mate transmitter. (UX245 TNT. ) I would have given it a shot.
Don VE3LYX.

Are you sure you are using a UX201A? That one should draw 250ma, which is slightly less than the 6SL7's 300ma. If it's a UX201 (without the 'A') that you are using, it would draw 1 amp of current on the filament. I'd expect a UX201 to eat filament batteries like crazy, but not a UX201A. The original UX201 had a pure tungsten filament, but the later UX201A had a thoriated tungsten filament. The thoriated tungsten filament allowed the filament to be much more efficient, and so less current was needed to supply enough available electons. Besides the filament, the UX201 and UX201A were the same. Of course, still later, the number was shortened to just 01A.

BTW, that UX245 will draw 1.5 amps on the filament. Expect that to really eat batteries, if that is what you are using with it....

Norman
KA1GUK