[Milsurplus] More GRC-9 Bias Battery stuff!

[Ray Fantini]

Wow, Energizer Industrial Nine-volt batteries are easy to open and do provide 1.5 volt cells that can fit into the plastic shell of the Bias battery on the GRC-9, they also have tabs attached so you can solder them. I know what I will be doing this weekend!
Going to rebuild the bias battery and am taking into account everything that has been said so far. The manual says that the battery is needed for improved audio response although I think that's a bit of a Red Herring. Looking at the plate current curves for the 3Q4 I am more inclined to think they had the tube biased that way because the plate current is half of what it is with no bias and being the audio output tube draws more current than any other tube in the radio, they did that to get maximum life out of the B Battery if you were using the radio that way. Remember that the receiver was capable of running from a dry battery pack in the field where you would only have to crank the generator when transmitting. Overall current drain in receive would be a big factor and the designers of old were skilled at building battery powered radios that got long hours of operation from dry batteries. I had a TBX-6 that only drew about 10 Ma @ 90 volts for the receiver and was always impressed that anything can run using that little power.
In regards to the gauge of the wire in the output transformer I have a hard time imagining it being 40 gauge, but if it is 40 gauge is only rated for about 15 Ma, it's only a guess on my part but I would think more along the lines of 24 or 28 gauge and that is good for around an amp. But that's just my speculation and as my wife will be the first to tell you I am often wrong.
Ray F/KA3EKH
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