This is a Swan 350 I restored and made a few changes to. This rig was amazingly clean inside, with no signs of mods or hacks. I replaced all of the electrolytic caps, a few out of spec resistors, cleaned and tightened the power supply cable connectors, cleaned the tube sockets and tested the tubes. Once up and running, it got a full alignment. Despite checking good, the finals wouldn't neutralize, no matter what...so, in went a new pair of tubes :-)
After I had it on the air a bit, I noticed the AGC response was way too fast for my taste. I don't like hearing noise between words of the received signal when in phone mode, or lots of noise between dits/dahs on CW. I changed a cap that controls attack rate to solve that problem. Info on that in the photos. Here's a little video to cover this mod...
Next, I found a problem with the carrier osc injection level at the product detector. This is not uncommon, I've seen the same in Heathkit, etc. You'll notice this when STRONG received signals sound metallic or distorted, but clear up when the RF gain is reduced. Carrier osc levels should typically be 3+ times more than the IF level at the product detector, and can be cured with a simply cap value change. Here's a little video that explains it:
The Swan 350 is a great rig and a blast to operate. I still need to paint the top covers, I'll get around to that. Swan has a funny little gap between to top covers and the cabinets, they all seem to have that. I wonder if it was intentional to improve ventilation?
Dave WB4IUY
