[Amps] AL-1200 Pop/Arching, 756 Pro II failure

[R.Measures]

>On Fri, 10 Oct 2003 21:40:48 -0700, Dana Roode <K6NR at ARRL.net> wrote:
>
>>A question for those with AL-1200 repair experience --
>>
>>I bought a used AL-1200 amp a few months ago - it has a low serial number, 
>>108, so I assume its pretty old.  I have used it in several contests and it 
>>has been working well.
>>
>>This weekend we were using it in the California QSO party when there was a 
>>loud pop and an arc visible from the side venting holes, perhaps near the 
>>filter capacitor and rectifier boards.  The Icom 756 PRo II I was driving it 
>>with went south at the same time - no transmit power (received everything 
>>else was fine).  The Pro II is headed back to Icom for repairs.
>
>_________________________________________________________
>
>I had a similar experience with my AL-1200 which I bought when they
>first came out.  In fact, it happened twice.
>
>In the first case, I was running RTTY in a contest and the tank coil
>overheated.  ...

€  I have heard reports of this too.  It seems to me that the diameter of 
the conductors selected for Ameritron tank inductors needs to be greater 
in order to reduce I^2 x R loss.   Also, adding a cooling fan directed at 
the tank L and the bandswitch would help.  . . .  This is one thing Heath 
got right in the SB-220.

-  R.L. Measures/Rich..., AG6K, 805.386.3734, www.somis.org