[Swan] Swan 400 80 meter outage

[Jeff]

Trying another post on the topic...

Was just about ready to close up the 400 I'm redoing, and decided to 
test 80 meters into the dummy load.  I saw smoke and immediately shut 
down.  Looks like I cooked the RF choke L306, although it still had 
continuity at about 7 ohms.

I ordered a couple of new 200uH chokes and installed one, and also put a 
small capacitor on the driver variable cap per the service bulletin.  
The good news is that I have full output on all bands EXCEPT 80, and the 
new choke seems fine.  Also good news that I'm getting SOME output on 80 
meters - maybe a couple of watts at most, but enough to read on the 
counter.  For what little output there is, it appears that it's right on 
frequency.

So, I'm leaning towards a band switch problem, but I just don't know 
where to begin looking.  Visual inspection, cleaning and such doesn't 
reveal any physical damage. Straight continuity checks on the switches 
seem to be ok, but it's hard to tell for sure. I've replaced a number of 
resistors, but haven't found much grossly out of tolerance. (Followed 
your suggestions, Bill - W4WHW).

Can someone help me decipher the signal path for 80 meters so I can 
determine where the it might be breaking down? I can inject an RF signal 
into it and follow along with the scope, but I'm just smart enough to be 
dangerous on this tactic.


It's frustrating to be so close on this rig...

Thanks lots!

Jeff

WB3JIH