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

[Bill Turner]

On Sun, 12 Oct 2003 05:52:01 -0700, R. Measures <r at somis.org> wrote:

>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.

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IIRC, part of the problem in the AL-1200 is the hot air from the tube
exhaust is vented inside the cabinet instead of to the outside.
Changing that and adding a fan as you suggest would probably take care
of the tank coil overheating problem.

The 80/160 tank coil is just a cheapo type made with polystyrene
strips, similar to a B&W miniductor.  At that power level, I'd think
it should be either wound on a ceramic form or else it should be a
stiff, self-supporting air core type.  

-- 
Bill, W7TI