Im currently playing with a one tube regen, soon ill be adding an audio stage with a type 30. I was using the type 30 as my detector but i found that a cx301a seems to work just as well and a 201a almost as good. Though I got only two bands that were blurred into one with an 01a oddly enough.

Im running a 45 volt plate, is there another tube i should try for a detector that is early, 4 pin and will operate on the smaller voltage im running?

Sorry for all the questions, im new at this. But having a lot of fun.

If you use tubes, the detector might work better on 22 1/2 volts, and the amplifier on 45.
Also the 30 detector can be adjusted by putting a 50 ohm rheostat in series with the filament.

You can run much lower than 45v and have better control over the regeneration. The trick to peaking out a regen is to have good hi-Q components in the RF loop and fine control over it to where its not subject to 'plunk' and 'hysterisis'.

In theory a regen has infinite sensitivity and selectivity although it doesn't always work out that way down on the ground

some other 4 pin tubes are the 864, and the UX199

People spent alot of time in the 20s trying to optimise what they could get from the one tube. Of course you need to start with a good tube, but they also worked to optimise "low loss" tuning components, variable grid leaks, etc. Sensitivity of headphones can help more so than on a multiple tube set. I used a 22 and half volts battery for a long time for a detector B+ here, until it went flat. The next alternative would be a couple 12 volt batteries in series, or 3 9V batteries, which will give you the somewhat higher 27V to start with. You might see if you can obtain a 200A tube that is supposed to be optimised vacuum for a detector, versus amplifier. 200's are around, but they draw alot more current for the filiment and are best used with a rechargeable filiment battery. I have tried several different 201A tubes in regen. detectors and some play louder, some may have more ultimate sensitivity, etc. I have not altered an old set to have a variable grid leak. But you could make substitutes if it uses plug in types. That might be something to mess with, maybe try 1-10 megohms range and see if one value is best. I suspect with so many makers, that tube could vary alot in characteristics. Maybe not so much with the 30 tube. And you don't have to run the filiment on your tube any higher than what it takes to get good regeneration, thus extending the life of the tube, probably.

200A tubes are easy to find. I have 3 or 4 from a buy I did last year. I wonder how one would work in my Victoreen superhet?

Amplification factor is also greater with a '00A (and a lower "B" current drain).
20 v. 8
http://www.shinjo.info/frank/sheets/021/0/00A.pdf

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well im on the lookout for a 200a and 00a, theyre all fairly close and not that hard to adapt to this.

The 301a ive been trying seems to be a rather good detector, at least in this design.

Id love to try some of the very early detectors, like the wd11 and wd12.

What are some of the very first detector tubes?

00A is the later version (same tube, different bulb) as the early globe style 200A (RCA) and 300A (Cunningham) tubes.
'00A And '01A are the generic terms for these early triodes.

Some equivalent info here:
http://www.vacuumtubesinc.com/TubeTidbi ... lents.aspx

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00A is a great tube but nowadays the threshold voltage on any individual one has likely changed. You really need to be able to adjust the B+ to tweak them to max performance.

Very early? De Forest Audions, though you probably wouldn't want to run one for very long and have it burn out. After that, Cunningham Audiotrons and similar tubular detectors were popular, Moorhead Electron Relays, and dozens of wondrous tubes promoted in the back pages of QST or the back rooms of radio shops.

I've found 200s and 200As to be quite variable, and some don't work at all. If I were investigating them now, I'd use a curve tracer, but I didn't have one thirty years ago.

Forget WD-11 & 12. Just too costly to mess with, especially WD-11's. They are much in demand by folks with early Radiola, Aeriola, etc. exposed-tube sets. And, they are not particularly hot performers. And, they are rather delicate too.

The 00-A tube is probably the most sensitive tube you'll find for use as a regenerative detector. Some 00-A's exhibit a pronounced variation in performance with change in plate voltage, typically peaking around 16 to 18 V. Some early sets actually incorporated a potentiometer to permit fine adjuistment of the detector plate voltage.

If I recall correctly, back when this tube was popular, they recommended that the grid circuit return be connected to the + side of the filament instead of the more conventional - side (or, maybe I have this backwards ... don't remember for sure).

Most of the really early tubes are just too valuable as "collectibles" to experiment with. One fairly common early tube that's not too pricey and is quite rugged is the UV-200 or C-300. They look really neat in operation ... bright as a small light bulb. These tubes are even more fussy than the 00-A as to plate voltage. Also, they take 1 Amp of filament current, so you have to have a battery or power supply capable of that, AND a filament rheostat capable of handling that current without overheating. Probably because these were made before they got manufacturing down pat, you will find performance varying widely from one example to another. There is a slightly later (and more stable & uniform in characteristics) version: UX-200 or CX-300.


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DD

Sometimes some tubes seem to have more volume or play a bit louder. For driving headphones with a single detector. And perhaps you don't need super sensetivity nowadays as much anyway, maybe signal levels are higher at the input. In the very early 20's I think most broadcasters were lower powered affairs. Now with most AM stations running pretty high power, that has to help. Therefore with a single tube I might opt for best volume level, first. But there are other variables, like antenna, grid leak, and voltages that can have as much effect as the tube variations.

In the 20s the aerial was the focus of radio people, and was a status symbol on a street,
not necessarily of wealth, but showing an understanding of the 'Brave New World'
that was ahead.

Whatever you do with your detector, put as much thought into the aerial and the ground system.

And if you can keep it battery operated, it will be be cleaner.

Sure nuff, I had it backwards.

Here's what the 1924 edition of "Practical Radio" by Moyer and Wostrel says (page 63):

"In the case of the soft vacuum tube, the presence of gas in the tube changes the action. The grid current in a soft tube tends to flow at a much lower of positive force between the grid and filament. Although a grid current is necessary, too much is harmful andfor this reason the return wire from the grid is connected to the negative side of the "A" battery."

I'm not sure how much difference it really makes in practice, but that's what the book says. I have found 00 and 00-A "soft detectors" to work just fine in several regenerative radios without changing any of the wiring. Maybe some day when I'm really bored, I'll switch back & forth and see if I can find any difference in performance.


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DD

I'm almost certain that you had it right. With a low B+, the grid needs all the help it can get.

Look at detector circuits in early battery radios. Grid is returned to positive filament terminal in only the detector circuit.

Splitdorf tried returning detector grid to negative filament and didn't work well. They ended up connecting plate to the positive filament rather than 22 1/2 volts. Ended up to be more like a diode detector without gain. This was only done on a few models and is not shown in Rider.

Thank you all for your advice. Im currently trying the doerle two tube regen design with the type cx301a as a detector and a type 30 in my rf section. Ive found that varying the plate voltage on the detector seems to help pull in some stations. I added an external tuner for the antenna, which is your basic 14ga 75ft wire hung about 35ft feet off the ground and ive a great ground connection. I connect right onto a buried oil furnace tank.

I bought a vernier dial to help with my tuning, but have yet to install it. Im picking up a 200a this sunday and see how it changes my receivers characteristics.

But yes, i realize im acting like a kid in the 20s, just experimenting and trying new things, not knowing a lot. I know these tubes are collectable and rare, so i make sure to keep the filament and voltage at low operating levels to hopefully preserve them.

Don't sweat a commoner tube too much. Apparently there are still tons and tons of regular 201A types floating around and you can probably thank all those high tube count later 20s sets that no one wants now. Because of the tube count and the table space required to employ them. The tube was even still in production for awhile after being obsolete, due to demand, because of the supplies of ST style ones you see. 30s are getting expensive but are not rare, either. And besides the FETs concealed in dud tube bases to restore funtion, I wonder if some of the more common filiment heated submini triodes could be hidden in a dud balloon tube somehow. To maintain VT type functions.

I like experimenting with twenties circuits also; it's a lot of fun. I'm just worried about your ground going to a buried oil tank: a lightning strike could make some bad ka-blooey.