[R-390] Tracking down low sensitivity 0 to 8 mhz problem

Jordan Arndt Outposter30 at shaw.ca
Wed Apr 3 15:53:21 EDT 2024


Hi again group,

Ok..I'm now able to adjust T207 to produce -7.6 Vdc at E209, so the effort 
has been rewarded.

I wish I could say for certain what the cause for the prior low output has 
been, but I did not find a faulty component including coil resistances, a 
bad cable or connector, or anything else. Even C227, the .047uF PIO cap 
tested fine after I replaced it with a film cap.

I replaced C268 and C327 with Mica caps, an 82K resistor and thoroughly 
checked wiring and switches.

The one thing I did find was that C275 had been replaced with a .0033uF cap 
rather than the .033 called for. I'm not exactly sure what effect that might 
have had, but there was a reason for the published corrections.

I'm going to do some contact cleaning and a little lubrication before I 
re-intall the deck and move closer to the finish...

73...Jordan VE6ZT 



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