FT-757 transmitter bursting into osillation
 

Bought radio with blown final which I repalaced with same gain color
dot . You can key the transmitter on ssb as soon as you talk off it
goes into never never land . tried changing the 1000 uf cap at the b+
input no help. I don't know what stage is talking off. the tools at
hand are a 35 mhz scope and a freq counter and of course a dmm with cap
checker.

help
jon b

FT-757 transmitter bursting into osillation
 

KA2JBY wrote:
Bought radio with blown final which I repalaced with same gain color
dot . You can key the transmitter on ssb as soon as you talk off it
goes into never never land . tried changing the 1000 uf cap at the b+
input no help. I don't know what stage is talking off. the tools at
hand are a 35 mhz scope and a freq counter and of course a dmm with cap
checker.

help
jon b ,,,,,,,,,Jon, I have found that the most critical thing in these high power devices is the BIAS... Get the service manual and make sure the PA bias is correct .. could be the reason for original failure ...GL Harold

FT-757 transmitter bursting into osillation
 

Inductors in final stage all shielded from each other?
--
god bless

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