[AMRadio] GK500 OTA almost


w5jo at brightok.net w5jo at brightok.net
Mon Jan 2 22:50:48 EST 2017


Is the set unmodified in the tank circuit?  If it is stock, check the mica 
capacitors on the coarse loading switch or the contacts on the switch (I 
have seen the switch mis-wired).  Have the coils been changed in any way? 
You don't mention which band, is it on 160, 80, 40 or all of them?

That is just a shot in the dark.

Jim
W5JO


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


Dear AMers,
I am having a time with this Globe King 500B. I have it ready to make RF but 
no modulation yet.
Something is just not right and I can't quite put my finger on it yet. Maybe 
some of you have had an experience like this and might be able to lend me a 
hand.
Tuning the final goes fairly well until I take it out of tune and the full 
screen voltage is applied to the final. Tuning is very touchy acting and 
reaches a point where plate current suddenly pegs the meter and some 
arcing/flashing happens inside of the tube. I can tame this and get it to 
stay stabilized but increasing loading and the plate current pegs. Any 
ideas?
I have cleaned and secured grounding of tune and load air variable 
capacitors and also disassembled each air variable and cleaned and buffed 
all contact surfaces. I have cleaned the final tank band switch. I have 
inspected every connection and contact between the antenna connector and the 
plate cap on the final amp.
I will not give up!
Good Day, Collin





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