[Johnson] Adventurer filter caps

[Dennis A. Deaton]

Charles,

A lot of guys use strings of lower voltage capacitors to replace the
700-Volt units found in these transmitters. In my Adventurer I've used three
33-uf / 350-Volt caps with 270K-Ohm / 1-Watt equalizing resistors around
them. The 1-Watt rating on the resistors is necessary because of the
200-Volt+ potential around them. Collins used this same string in the 516-F2
S-Line power supply. You need to use the equalizing resistors because
electrolytic capacitors have capacitance tolerances of -20% to +100% which
throws the instantaneous voltages across them all over the place. 

Dennis, WA6ACC

-----Original Message-----
From: Johnson [mailto:johnson-bounces at mailman.qth.net] On Behalf Of Charles
Ring
Sent: Sunday, March 1, 2015 8:07 PM
To: johnson at mailman.qth.net
Subject: [Johnson] Adventurer filter caps

The original Johnson Adventurer filter caps are two big old axial 8uF 700V.
What is the proper way to replace them? Seems the originals are really each
two caps in series in one paper enclosure. Two 20uF 400V directly in series
replacing each one? Equalizing resistors needed?

--
*Charles Ring W3NU*
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