[Amps] AL-80A - Won't tune on 160m.

[Bill Coleman]

> On Jun 22, 2016, at 6:56 PM, Bill Coleman <aa4lr at arrl.net> wrote:
> 
> I managed to fix my issues with the metering circuits on the AL-80A. However, while it appears to work correctly on 80-10m, I cannot get the output network circuit to resonate on 160m.
> 
> I hooked it up to a dummy load, fed about 35 watts, keyed and tune. Peak output is achieved at maximum C for both Plate and Load, but it’s only maybe 100 watts out, and the tuning is very broad. Nothing like 80m, which works fine.
> 
> Any suggestions?

I finally got the AL-80A on the bench again and found that the switch contacts for the extra plate circuit capacitance are burnt away. Since I’ve never used the amp on 160m, this wasn’t me, but probably the previous owner.

So, this problem is at least identified. I’ll have to either replace the contacts, or the entire switch wafer.

Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr at arrl.net
Web: http://boringhamradiopart.blogspot.com
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