> On Sep 5, 2016, at 11:53 AM, Bill Coleman <aa4lr@arrl.net> wrote:
>
>
>> On Sep 4, 2016, at 11:26 PM, Vic Rosenthal 4X6GP <k2vco.vic@gmail.com> wrote:
>>
>> This is a common problem with this amp and the SB-1000 which is similar. You
>> don't need to operate on 160m for this to happen. Here is an article which
>> discusses the placement of a "corona washer" on the bandswitch to prevent
>> this. Make sure you install such a washer when you fix the switch:
>>
>> <http://www.northland-drifters.net/SB1000Project.htm>
>
> Will do!
>
>> The article also suggests replacing the parasitic suppressor with a
>> different type. The original style parasitic suppressor is fine as long as
>> the carbon resistor hasn't changed in value or even opened up. I would check
>> this resistor and replace it if necessary. The nichrome type of suppressor
>> isn't better and heats up more on 10 meters than the stock type.
>
> Yes, I’ve read the debates on this.
>
>> Also while you are at it check the plate RF choke. There were several
>> different chokes used in the manufacture of the AL80A and the early ones had
>> a series resonance on 17m, which caused them to burn out if operated on that
>> band. If the choke is one solid winding without gaps, replace it with an
>> AL80B choke that you can get from Ameritron.
>
> Uh. Yeah. I have no choice but to do this now… Part has been ordered.
Just a follow-up. Replaced the RF choke, replaced the switch contacts, added
the corona washer.
You can read about the repair on my blog:
http://boringhamradiopart.blogspot.com/2016/09/ameritron-al-80a-fixed.html
Thanks for all the help here. Amplifier has been working great!
Bill Coleman, AA4LR, PP-ASEL Mail: aa4lr@arrl.net
Web: http://boringhamradiopart.blogspot.com
Quote: "Not within a thousand years will man ever fly!"
-- Wilbur Wright, 1901
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