[Heathkit] Heath audio, rough around the edges.

[Jim Shorney]

Hi Bob,


On Sun, 18 Jun 2006 16:49:46 -0400, Robert P. Ward wrote:

>	The way I went about it might not be easily accomplished by others.


Boy, I'll say!  :) I don't have that kind of gear at home, and they might
look at me funny if I hauled a boat anchor in to work....


>	I'll give you the data that I compiled here.


So it looks like you moved things about 200 Hz. Sounds reasonable.


>
>	I hope this was helpful to you Jim.


Yes, thank you. When I pull the SB104A out of mothballs, I may do some
tinkering.

Let me run this by you. What I was thinking came from an old HyGain CB radio
service manual (model 623 to be exact) and seemed to be a really simple
method of setting carrier oscillators. I'm doing this from memory, so
apologies if it is not exact; I would have to go dig that manual out of my
archives to look it up. Anyway, the method involved feeding an audio
generator at 1 KHz into the MIC input and adjusting for a relatively low
power output on SSB transmit. The audio generator is swept across the audio
passband to determine the point of maximum output, and the level is set to
read exactly full scale on the reference meter (an SWR meter set to FWD,
IIRC). Then the audio generator is reset to 300 Hz IIRC, and the carrier
oscillator trimmer is adjusted for exactly 1/2 scale reading on the reference
meter, thus placing the -3 dB point (or was it -6?) of the filter skirt at
300 Hz (or whatever the frequenchy was... might have been 250 or some other
value in that area). Since the carrier oscillator is also the BFO, this sets
the RX also.

Now, if we could correlate your settings to what the audio frequency at the
mic input would be at -3 dB, then we have a method that anyone can duplicate
with minimal test equipment. 


Just wildly speculating....


73,

-Jim


--
TR7/RV7, TR6/RV6, T4XC/R4C, L4B, NCL2000, SB104A, R390A, GT550A/RV550A - all vintage, all the time!