Tristar 747

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M1JWR
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Joined: 08 Apr 2011, 10:48
Location: The Debatable Lands

Re: Tristar 747

Post by M1JWR »

Hi
Where would i start with lead throughs
However after looking for more obvious things i noticed that all other pics
of 747's hygain v's etc have a green wire that goes from a point just above the avr
to a point just above q36, this radio dosent have one, nothing ventured nothing gained then !
so i fitted a wire, it made some big changes to voltages and on q36 is as follows
B 10.34v rx
C 13.66v rx
E 9.9v started a bit higher than that on first touch with probe rx
have re checked some of the bt bts's etc and their voltages are now higher than spec
may have to go on back burner for awhile till i get a sig gen
regards
M1JWR
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Posts: 345
Joined: 08 Apr 2011, 10:48
Location: The Debatable Lands

Re: Tristar 747

Post by M1JWR »

In TX
B 8.9v rising slowly
C 13.01v
E 7.6v rising slowly
M1JWR
Super Member
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Posts: 345
Joined: 08 Apr 2011, 10:48
Location: The Debatable Lands

Re: Tristar 747

Post by M1JWR »

Bit of a postscript on this until i find a sig gen
i now know why they put the green wire on the circuit board
it takes full 13 point whatever voltage from r148 to one leg of rv13
wonder why they did that, this radio looks like it dosent need it.
so it is now removed.
i have tested the 2 older 2sd325 avr trannies against a new one and both are good.
when i refitted one of them i rechecked it and q36
the avr on emitter and base are both just over 12v (bit high)
i quickly checked q36, that is now on emitter and base within around
10 millivolts of correct spec rx and tx
apart from voltage checks i am shooting in the dark until i get a sig gen
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