Topband: SB-1000

Tom W8JI w8ji at w8ji.com
Thu Dec 17 15:30:17 EST 2015


> Just came off 20M, amp working fine. Went to 160 plate and load controls 
> have no control, no output. Plate current climbs high with any added drive 
> (45-50W) and blew both 10amp fuses.Off comes the cover.jimk2hn
> _________________

It might be something else, but  I would bet the contact on the 160 padding 
capacitor is burned off. This is what the anti-corona washer reduced. Heath 
did not use that washer.

It arcs there when the loading cap is too far closed (too much grid current) 
for the amount of drive on higher bands, or if the antenna should become 
grossly mismatched when at high power on bands other than 160.  The worse 
band for arcing the 160 padding contact is when on 80 meters.





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