I opened my Radiola 25 and found that the grid leak resistor was falling apart. One end broke off. It is not marked as to value. It is solid red and was probably either before standards or "proprietary". Does anyone have a Radila 25 that they can take a simple measurment on for me? First remove the battery connection strip on the terminals, adjust the filamnet and volume knobs to midway. I need the resistance between G4 and terminal 12. Tube 4 G4 is at the 4:00PM (bottom right)position when facing the front of the radio. Terminal 12 is counted from the left facing the radio.
Alternatley, anyone who has replaced one just might know the value?
Jeff

The grid leak in an AR812 (the earlier 6-tube superhet) is 5 megohms. I imagine anything from 1 to 10 will work.

Alan,
Thanks for the help. I have been told that the selection of grid leak resistance effects selectivity and if too far out, can also cause distortion (see earlier Radiola 25 Test posting response). I am hoping to restore the precise original design (based upon a respect for design engineers and desire for authenticity). Call me a nut but I like to keep things as close to original (including component values) as possible. I can, for now, try several different resistors starting with 5M Ohms for best effect, or temporarily install a potentiometer (if I can find one with a wide range) and dial it in. I would still really like to hear from a 25 owner. Is anyone out there?
Thanks again Alan!! This forum is great!
Jeff

:The grid leak in an AR812 (the earlier 6-tube superhet) is 5 megohms. I imagine anything from 1 to 10 will work.

>(based upon a respect for design engineers and desire for authenticity)

I used to correspond with one of the designers, Wendell Carlson. Among his other accomplishments was the invention of AC biasing for magnetic recording. He was so far in advance of anyone else, that it had to be reinvented years later: he got his patent in the early 1920s!

Alan,

That must have been very interesting communication.

I have my name on two patents, and I understand the excitement that comes creating new technology. Mine are not related to radios, nor are they making me a rich man. They just look good hanging on the wall.

Too bad this type of information is not available somewhere. I doubt that it is just sitting in a file drawer. I have ordered two potentiometers with 0 to 5Meg Ohms and some fixed resistors with relatively high resistance. I will experiment until I get the best results or find someone who has one to measure.

Once completed I will submit a schematic to you folks with the correct values for the grid resistor and the capacitors which are sealed within the catacomb section.

Jeff

:>(based upon a respect for design engineers and desire for authenticity)
:
:I used to correspond with one of the designers, Wendell Carlson. Among his other accomplishments was the invention of AC biasing for magnetic recording. He was so far in advance of anyone else, that it had to be reinvented years later: he got his patent in the early 1920s!