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 Tentec 515 repairs 
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Post Tentec 515 repairs
Lets see how we get on...


I am repairing a TT515 5 watt radio.

It works reasonably well except that...the power is right down, instead of 5w I get about 300 mW and lower on 80 and 10m theres nothing. The finals devices (mrf746) get hot to touch.

See attached image for the RF PA board which is where I have started

The resistor R1, 100 ohm, had gone blackened as far as I could tell WAS 100 ohm, although it looked like10 ohm (brown black brown, which might have burnt to to Brown Black Black). It was also open circuit.

I changed it for a new 100 ohm unit.

All caps (0.1u / 100nf) are DC open and “around” the 100nf mark (125 - 80)

Why else are my finals getting hot but no RF…where else should I look next?


All voltages are reasonable. except…

The standing voltages on the pa devices s/be

B0.7
C13
E0

Whereas I seeB0.8
C13
E0.37 / 0.15

So I think there’s something not right here

Any thoughts?


Attachments:
RF Amp board.jpg
RF Amp board.jpg [ 100.27 KiB | Viewed 201 times ]

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David. G4YVM
Fri Aug 30, 2019 12:18 pm
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 Tentec 515 repairs 
Contributor 2018
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Joined: Fri Sep 14, 2012 5:32 pm
Posts: 4469
Location: Salisbury, Wiltshire
Feedback: 20 (100%)
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Post Re: Tentec 515 repairs
Well one of the pa trannies is not right. One tests fine, Hfe 22 but the second shows zero. Oddly (to me) the tester still sees it as a proper MRF746 even though it it clearly not working. I think new PAs called for.

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David. G4YVM


Fri Aug 30, 2019 5:10 pm
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