[Drake] TR7 Transmitter Troubles

[Darrel Nichols]

Thanks to all the responses on the TR7 alignment.   Getting ready to go back in there.
Consensus seems to be the PIN diodes, even though I've checked them many times.

I've received several queries from folks having the same problem as mine.  It must
be very common indeed.  Some of the experts out there should do an article on it!

I've found curiously that setting up according to service manual instructions, I.E,
predriver full CW, 20 meter band, adjust ALC for 120 watts,  mine will then oscillate
on 75 meters in CW mode with carrier turned fully off!  My feeble mind suggests that would
eliminate the diodes and the finals.   I'm wondering if anyone else can duplicate these
findings.

I'll try and report anything I figure out back to the list, but so far have heard of
the following commonly encountered troubles:

1. PINs.  (Well covered on net resources)      
2. SWR bridge has to work spot on with perfect null.
3. Dummy load needs to be high quality 50 ohm unit (sorry MFJ owners) during testing and alignment.
4. Bandswitch alignment and filter grounding.
5. Finals must be in top shape.

N0DBX

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