[Amps] Source of Mica Caps?

[Jim Thomson]

> IMO, you gotta be nuts to use grid caps + chokes on any 3-500Z amp.

** OH? So you and a few other glorified techs want to argue with experienced 
engineers that designed the amps? I give them the benefit of the doubt 
considering the number of Heath, Drake, KW, and other amps out there that 
far exceed the very little minority that believe "if it aint broke dont fix 
it"

## engineers that designed the amps ?    Surely you are joking right ?   They are not engineered,
more like ill conceived.  The heath needs a real bandswitch, with a real detent.  And 6:1 verniers
for both tune + load.............+ step start ..+ a standby-operate switch etc, etc. 

## On a side note, a buddy in W7 land with a SB-221 tells me he has severe TVI  into his neighbours
satellite setup.... but only on 17M.  I get him to grnd the grids.   He did so but with using just ONE piece of
solder wick, and ground one grid pin per tube only.  He left the caps + choke in place.  Presto, TVI gone.
But that may have been one of the caps  acting up on 17M, dunno.   he was using a F-12 20-17-15-12-10m
yagi.  Drive power dropped at least 20w, and amp is stable with stock suppressors.  

##  Another friend has a very unstable TL-922.  He installs  richs nichrome and all is well.   he tries bonding the
grids to chassis, and drive requirements drop 20-25 w.  Amp still stable.  Then he removes the nichrome and installs
the oem suppressors..and amp is rock stable.   Removes grid bonding straps, so grid caps and chokes are back in the
circuit.  Amp is now unstable !  CC  resistors in the oem suppressor’s are fine. 

##  This time all 6 grid caps are tossed, + both chokes.   been like that for several years now.   I must have got email from
at least 30-40 folks now who have bonded the grids to chassis  on sb-220’s, and also 221, and tl-922.  

##  adding a glitch r is no big deal.  25 ohm 25 watt wire wounds, 2 of em in series,will allow  one to get them in there. They can be
far apart if you want.   Adding a 50 ohm, 50w  ww to any drake amp is easy.  I have done the drakes  by installing in either the 
outboard drake hv supply  or the rf deck itself.  

##  since most folks will add a glitch R  of some type to these older amps.....adding a simple HV fuse,  just prior to the glitch assy
is pretty easy.   A single fine strand of the correct gauge, is all that is needed.   Then cover the strand with heat shrink, or 88 tape,
teflon spaggeti tubing etc.  Any anode to grid flashover, and hv fuse opens up..event over...no follow on current either. 
Drake uses a  .82 ohm @ 1/2 watt  resistor for a  B+ fuse.   Blows  clean in half.  Works just as good as a hv fuse.  
A hv fuse will open up a lot faster than any 240 vac mains relay /contactor.   2 msecs  vs 35 mecs/. 

Jim   VE7RF