[Boatanchors] FW: [Johnson] Valiant Troubleshooting Question

[Jim Wilhite]

My recollection is the three are 3, 6 and 900 PF Mica sandwich capacitors 
switched in 1 step per position then they are added together to give 1800 pf 
total but in steps.  The problem may also be that the rear wafer of the band 
switch arced from one side to the other.  The front of that switch is the 
input side of the Pi network and the rear side is the output side.  If 
something causes an arc between the little rivets on the center of that 
switch it will exhibit the symptoms mentioned.

That is but one of the possibilities and Rob's suggestion is a good one. 
Some of those doorknobs are good for RF and some aren't.  Check carefully to 
be sure.  As I recall the 858 series will work on all bands covered by the 
Valiant but do some research.

You can also look for similar values in the micromold A2 series @ 1200 volts 
then stack them together.  My preference would be that but the 2500 volt 
versions.

-----Original Message----- 


I've never owned a Valiant and don't know how the space is but if
possible I'd replace those mica caps with two small RF HEC doorknobs
for ~330 pF and 150 pF.  Try to find class 2 dielectric temperature
and RF current figures at 1 Mhz before buying.  RF parts has that kind
of data with their HEC doorknobs.   You might be okay with disk
ceramic caps but on 160 m. AM they can drift.