[Collins] KWS-1 ALC

[Gerald]

On Tue, 2006-02-07 at 19:12 -0500, david knepper wrote:
> I have a KWS-1 that was converted from the 6X4 to the later 6AL5 ALC 
> rectifier circuit.   I want to retain the 6AL5 circuit but need to know if I 
> could install a pot somewhere in the circuit to control the ALC.  The 
> previous owner placed a key lock switch in the hole that was used for the 
> original ALC design.  The front panel is the former style that has the 
> markings:  ALC adjustment with those graduated scale and I really have my 
> reservations that I could cover up the silk screening and restencil to show 
> "Lock Key" "Off and On."
> 
> Thanks
> .
> Dave, W3ST

How much else changed when the tube changed? The 6AL5 could produce more
ALC voltage (as a voltage doubler) that the 6X4 didn't do, but the 6X4
could work with a higher voltage RF sample off the plate instead of off
the grid circuit using any detected grid current that would take the PA
tubes from AB1 to AB2. 

I just don't know those revisions of the KWS-1 circuit. If the later
circuit didn't use a gain control, perhaps it wasn't needed because of
the different source of ALC sample voltage.

For custom labeling on an overlay, you could use a Leroy lettering set
with thinned paint, to do some of the lettering if the crackle didn't
get too much in the way. Though that crackle should have made silk
screening tough too.

-- 
73, Jerry, K0CQ, Technical Advisor to the CRA
All content copyright Dr. Gerald N. Johnson, electrical engineer