[Milsurplus] BC-230 questions and observation

[Mike Hanz]

Jack Antonio wrote:
> 
> 1. Anyone know the specs of the A-55 antenna?  I want to duplicate it for
> bench checks and transmitter setup per the manual. Right now the antenna
> terminal is fed through a 100pf cap, then to a 1 to 4 transformer, then to the
> 50 ohm load, and am getting .5A on the antenna current meter. The math
> works out to this being 3 watts to a 12 ohm load, so it looks like things are
> in the ball park.  The book says antenna currents run in the .8 to .9A range
> and am wondering if the A-55 load is 4 or 8 ohms and a cap.

Dunno - can't find a reference on the A-55, Jack.  If it's anything like 
the pre-1940 GF phantom antenna (also designed by ARC) then it's 20 ohms 
and 100pF.  Interestingly enough, the matching network in the ARC 
designed GF accommodates antennas within the range of 4 to 20 ohms and 
capacities of 100-200pF, which is a wider range than their later 
"command sets".  The recorded antenna currents are the same as yours, 
but a footnote says the set is feeding the 20 ohm phantom during these 
measurements.

> 2. Anyone look at the modulation envelope on MCW.? Mine is definitely
> NOT sinusoidal, or even close to it, and am wondering if this is normal.
> Voice modulation looks OK, a loud whistle looks clean.

No clue from the circuit description, but the oscillator overdriving may 
be intentional to improve 'hearability'.  A raspy tone is a lot easier 
to pick up.  If I get a chance I'll take a look at the GF-5 here and see 
if it has a similar waveform.

Best 73,
Mike