[ARC5] R-27/ARC-5 Hookup Question

[Neil]

Ken, thanks for confirming
73 de Neil ZL1ANM


>> I doubt it runs anywhere near 50 mA. It's connected as for Class A,
>> but is starved for current by virtue of the high cathode resistor
>> (1500 ohms if I remember correctly).
>
> 1500 ohms in early models: changed to 1000 ohms in later models to
> provide a bit more audio power output for some accessories.
>
>> The 12A6 will deliver 3.4 Watt of
>> audio if biased at about 35 mA, which implies a cathode resistor of
>> 390 ohms.
>
> Yes. Exactly that value according to the RCA Tube Manuals.
>
>> With headsets and even in a noisy aircraft, the 12A6 is never called
>> on to deliver more than a few dozen milliwatts.
>
> It is specified at 300 mW with the 1500 ohm cathode resistor, and 400 mW
> with the 1K cathode resistor.
>
> My restored ARC-5s will output almost exactly 400 mW....once I figured out
> how to accurately measure that.
>
> Ken W7EKB