[Heathkit] SB-102 RF voltages

[Edward B Richards]

Hi Bob;

My HW-100 manual has RF voltages. Since it is basically the same radio,
they should be similar. 

Wiper of carrier null control=1.0
T1, pin 1=.1
Both sides of FL1=.3
V3, pin 5=2.5
V5, pin 2=.5
V5, pin 6=.6
V5, pin 7=2.0
T202, pin 2=.3
V6, pin 5=2.5
V7, pin 2=2.1
V7, pin 6=45
V8, V9, pin 5=45
V19, pin 2=5.0
V19; pin 3=2.0

I had a similar problem; low output on certain bands. Everything checked
good. I aligned it 3 times. No improvement. I finally found the trouble
with a RF probe; low RF voltage on V5, pin 7 (1.0 V). The transformer on
the VFO sub-chassis was mis-tuned. I peaked it and ran a sensitivity
curve across the dial and it was essentially flat. The transformer seems
to be broad band. Just peak it at mid-scale (2.5 kc). The reason I missed
this was because the alignment procedure does not mention this
transformer (T941) and I followed the alignment procedure faithfully.
Good luck.

73, Ed Richards K6UUZ
AMI member #1534




On Sun, 27 Mar 2005 23:48:39 -0600 Robert Nickels <w9ran at oneradio.net>
writes:
> In my continuing quest to get this SB-102 off my bench, I wonder if 
> anyone has ever made - or can point me to a reference for - stage 
> gain 
> measurements on the SB-102 transmit side?  I've read several 
> articles 
> that agree transmit gain is on the low side anyhow, but wide open I 
> just 
> can't get more than 75 watts out on 20 meters even after trying all 
> the 
> regular tweaks and twiddles.   I can get full output on 10, leading 
> me 
> to suspect the 2nd mixer or driver but can't nail anything down.  
> The 
> info in the manual is pretty sparse, but if I had RF voltage 
> measurements from a known good working unit, that should help me 
> isolate 
> what's wrong.  Thanks for any help.
> 
> 73, Bob W9RAN
> 
> 
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