[AMPS] Ameritron AL-80 10m input cct.

[Chris Tran GM3WOJ]

Hello all

The air temperature on this reflector seems to have cooled
to a more reasonable temperature !

I'm renovating an early AL-80 (serial no.845) and there is a
problem with input S.W.R. on 10m  - the amp. has been an
'export' model and I don't think that the 10m input circuit has
been correctly installed.   I don't have any schematics so if
someone could describe the circuit (a Pi or L maybe) with
approx. component values, I'd be very grateful.

This early AL-80 had the worst cooling I've ever seen !   
Air was drawn through various holes around the PSU and tube
base, then exited near the PA tube, with a fine mesh filter fitted 
on the outside. In other words, dust was drawn through the amp. 
then trapped before it left !!   The air flow rate was far too 
little, and the amp. casing became too hot to touch after a few 
minutes of intermittent carrier testing/tuning up. I've reversed the
existing fan to blow cool air directly onto the 3-500z, and fitted 
another identical fan directly above the tube, drilling a pattern of 
small holes to allow the hot air to be drawn directly out.
Result = as cool as ..... a CQ WW contest from Scotland !

73     Chris   GM3WOJ/GM7V
gm3woj@talk21.com



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