Friday, December 20, 2019

Digging back into the AL-80A....

Front switch wafer - showing contacts burned
completely away.
Back in July of 2018, I was chasing the KH1/KH7Z expedition on 17m, and the AL-80A stopped producing any output. I dug into enough to find that the Pi-L output switch contacts had arced and burned. So, I jumpered the switch so the amp was only usable on 40m and above. And it has worked OK since then - but not on 80 or 160m.

It's way past time to fix this, so I recently got started. I figured that I just needed to replace a switch contact or two like I've done before.

Back side front switch wafer showing more
contacts completely burned away.
Once I got the lid off and removed the switch wafers, well, the photographs tell the sad story.

Middle switch wafer. You can see my jumper
between the to contacts on right. There was not
enough material on the switch wedge to make
contact with the 40m contact.
Replacing the contacts won't be enough. Plenty of the switch wiper was gone on the Pi-L (middle) switch wafer -- especially the corner that used to short out the Pi-L coil on 40m. And the 160m padder capacitor (front) switch wafer isn't any better.

No, this means I'll have to replace the switch entirely. I've ordered one from Ameritron, with shipping it came to $115! This is the AL-80B switch, which is similar, but not identical.

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