Building a radio receiver: Need help on the audio stages

[Beauregard42]

Howdy! I have a project going on right now, where I am building a radio receiver from old tubes I have(type 76s, type 41s, etc), and other components I find around. I know how to make capacitors, rectifiers, and a lot of other components, but the circuit itself is one issue. The detector is another, because I need a datasheet of the 76 with grid current specs, since I need to bias the grid to about -15 volts for it to work as a detector, and I can't use a battery for that. Any tips?

 

[Merlinb]

You don't need the grid current specs. Build the circuit with a guesstimate grid leak (try 10Meg) and adjust it until you do get the bias you need. It's only one resistor to tweak.

 

[Ixnay]

I gotta say it is pretty damned great to see that someone still appreciates radio. Like many of us out there, that was where my audio experience began. It was fascinating and magical at the same time.

 

[jhstewart9]

To do anything serious with early amps or radio find copies of the RCA Tube Manuals RC12 & RC14.
You could try Amazon, they started out in the book business.
Better still Alibris, https://www.alibris.com/
I found pristine copies of many technical books. Including Terman.

I've built many amps & receivers. These books were a great reference.
The photos are from a talk I gave at the local antique radio club a while back.

 

[jhstewart9]

The 41 is a 6K6 wearing a different coat.
There is also 6AR5 on a miniature 7-pin base

 

[stocktrader200]

Tubes do a great job with AM radio , not so much with FM.
I have my redone 780 tuner at 8khz frequency response on AM. The FM with new op amp filters is almost CD Quality.

 

[Hearinspace]

To do anything serious with early amps or radio find copies of the RCA Tube Manuals RC12 & RC14.

RCA Technical RC Series