[Collins] 30S1 Screen voltage

[Dutch Maurer WB7DYW]

I run a 30S-1 with this mod on the Sunday CCA net for hours at a time and it works fine, the 4CX1000 was designed to run with 325 volts on the screens and the amp was built to handle it....

73's Dutch WB7DYW
CCA Member #918

Success is not a place in time, it is an attitude…

--- On Fri, 1/7/11, John Hensley <w5jv at hotmail.com> wrote:


From: John Hensley <w5jv at hotmail.com>
Subject: [Collins] 30S1 Screen voltage
To: collins at mailman.qth.net
Date: Friday, January 7, 2011, 8:52 PM



I ran across this note on the 30S1 and wondering what list experience has been:
>>>>>The most popular mod. is to raise the screen voltage to 325 volts.
This is easily done by adding a small 100 watt isolation transformer
115v/115v in series with the winding on the screen supply transformer.
You then adjust the grid voltage and reset the r.f. sampling voltage
to the tuning meter.(The new transformer sits on the shelf above the 
main power transformer)

This mod doubles the power output of the amp while maintaining that
good, clean Collins signal.

Collins used 200 volts on the screen to limit the power input to the
1 kw limit to comply with the rules in the old days. This resulted in
an efficiency of around 25-30%. The above change has resulted in 
efficiencies of 58-66% in typical 30S1's.

>>>>>>>>                           
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