Hammond 850Q Interstage?
 

Does anyone have any experience with this 1:4 interstage? Their site gives its specs as +/- 0.5 db max. from 20 Hz. to 20 Khz - seems the best I've found (for the money).

I was considering 01A --> 850Q --> 01A --> 71-A or 45, single ended of course.
Damn 01-A's can't swing the 80V by themselves.

Joel

I'd save the 01A's for the radio fanatics, and find something with a little more gain, myself.

I got some old 01C's if you need them ;)
(same as 01A, but 1/16amp filament instead of 1/4amp, IIRC).

Joel,

20kHz upper BW limit is not enough.
1:4 IS trannies tend to limit BW. I would go for 1:2 or 1:1 IS trannie.

A 71A can be driven by a 56 or 76 with choke or CCS or 1:1 IS primary as load.
With a 45, it becomes a bit tough, then 1:1.5 IS might be preferable.

colt45,

I AM one the radio fanatics! Regularly pick up Radio Havana from Cuba with a single 01-A as a regenerative receiver. That's 1,200 miles. Not bad for 1925 technology.

Joel

RADIO
 

Hi Joel,

I noticed a few of the tube guys here are collectors of old radios too.
I think Tom Bavis is being one of them but there must be others.

Any chance of picking up a couple of Partagas cigars while you're at it?:D

Cheers,;)

Sorry Frank, but Cuba is off limits to us Americans...

Cool, ive been thinking of doing that as well.

I'd need an interstage tranny and a 4pin socket though, which I am lacking at the moment.

:(

no iron necessary
 

I know it's a bit off-topic, but here's the schematic I drew up for that receiver I've been using. There's no step up transformer needed (since the detector is the audio amp as well. You will need a set of high impedance headphones though (1,000 to 2,000 ohms). All of the parts are very cheap. Angela Instruments, or Antique Electronic Supply have 4-pin sockets.

ok, cool.

I was going to replace the headphones with an interstage, and feed it into a 6V6 or some other pentode.. maybe something that likes a nice low B+. (maybe a gain stage between the two tubes, i suppose..)
so I can drive a speaker with it.

whats the specs of the two coils marked T and S ?


I'd order a socket from somewhere, but by the time it gets here, and i pay for it, and shipping.. well its just not worth it for a measly socket.

I suppose you could probably make an ok regen reciever with a 6SN7 or 12AU7, etc etc,. first half for detector/amplifier, second as a gain stage to drive an amp..
(i might as well use one of my 01c's, they're not doing much good sitting here.)

colt45,

You need the headphones. Distant stations are tough to hear, and listening on a big speaker would be fruitless, even with the extra amplification. www.tubesandmore.com has them for $17

"S" and "T" are coils wound on the same form, 1/8" apart from each other. I use a 4 pin tube base from a burned out 01A. Any base would be fine. I have "S" as 16 turns of #24 enameled wire, "T" is 9 turns. This seems to bring in stations in the 5-8MHz range. Make sure both are wound in the same direction.

So, actually you need two 4-pin sockets, a tube base, probably a rheostat and the variable capacitor? Now it may be worth an order, huh?