[Johnson] More Valiant Progress

[John Lawson]

   Well - light at the end of the tunnel - not ready for the Air yet - but 
getting there.

   There are two problems - one I caused, one I neglected....  there are a 
pair of caps (C47 and C48 for those of you following along on your Books) 
attached from L's 11 and 12 to ground - L11 is the big pie-wound inductor 
between the finals and the tank coils that carries the doorknob on it's 
top - I had figured (hoped - ha!) that these would be okay, because 
they're Not Fun to get to, but I did my due diligence, R&R'ed the 
assembly - both caps were toast. Replaced them, now the rig loads up (into 
the dummy) almost like a real transmitter.


  I erred in ordering the capacitors I used to replace the old mica jobs 
in the RF and output sections - they are the right value and voltage, but 
just too small to carry the currents - as I proved by doing a bit of 
'marginal testing' - put it on the ragged edge and watch for smoke: I was 
rewarded by the 40M caps immolating themselves in a paroxysm of 
unworthiness.

   On most of the other bands, the transmitter is putting around 80 - 120 
watts of unmodulated carrier into my dummy load.  However the grid drive 
current is way too low - around 2 - 5 mils, instead of 8 where it should 
be.  With the drive on 8 mA, the plate current is in the "buy a new set of 
final tubes" range.

   Monday I'll order out some 'real' capacitors - I imagine there is a fine 
reason the Johnson engineers used series-parallel assemblies of molded 
mica units - and of course that wierd little 'capacitors on a stalk' thing 
- which in my rig was junk, so I replaced it with discrete units.

   Anyway - progress.

Thanks to the several of you who have written with advice and help - very 
much appreciated!

   Cheers

John  KB6SCO