[Heathkit] Any SB-102 Experts out there?

[Bwana Bob]

There were two modification articles that addressed these problems I 
downloaded them from the www but I don't remember where. Maybe they were 
posted on Mike Bryce's site or on the HW-101 site. One article was 
written by Mark, WB8JKR and is titled "Optimizing the Heathkit HW-101, 
SB-100-102 Transceivers. The other is titled "Improving the Heathkit 
HW-101 Transceiver"

The resistor and tube changes already mentioned will take care of the 
S-meter, but also clean the relay contacts.

On the rough receive audio, Mark's articles a mod to drop the IF gain 
slightly, increase BFO injection and trim the BFO crystals to get a more 
symmetrical passband.

On transmit audio, make sure you are not overdriving it and  check the 
neutralization.

I found the mod articles here on my PC. They are both PDF files. If you 
can't find them I'll e-mail them to you.


				73,

				Bob WB2VUF

This might be the source:
http://www.mines.uidaho.edu/~glowbugs/

Click on "Modifications and Upgrades".




Alex wrote:

> Hi Grant,
> 
> 
>>1.  The S-Meter won't zero.  I know there are some resistors to check, etc.
>>and hopefully that will be relatively easy to rectify.  Swapped out V3/V4
>>with a couple of other tubes, to no effect.  I was surprised that this
>>immediately obvious problem hadn't been noticed and fixed.
> 
> 
> I have an HW-101 with exactly the same issue. Checked and replaced resistors (with higher power handling capability), including the one suggested by someone else on this list, all to no avail. I swapped tubes around in the rig (I don't have spare tubes), but that didn't help. After many hours of checking I concluded that the rig has some leaky tubes. Since the rig performs great in any other aspect, I've decided to ignore the issue and just enjoy it until I can get some new tubes. Studying the schematic, especially the AVC circuit, I realized it's not just the two tubes mentioned most often that can cause a drifting S-meter. Every time I transmit it takes 15 minutes for the meter to drop to zero. I can live with that. :-)
> 
> 
>>2.  The receive and transmit audio are just a bit "rough around the edges".
>>I don't know how else to describe it.
> 
> 
> I had the same impression on SSB and I chalked it up to the fact that I have never owened a rig with crystal filters before. Maybe you can make an audio recording and post it somewhere for us to listen?
> 
> 73,
> --Alex KR1ST
> http://www.kr1st.com
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