Posts: 4,707
Threads: 51
Joined: Sep 2008
City: Sandwick, BC, CA
I think that there may be some conductive crap in one of the trimmers, a mixture of dirt, rust, and mouse pee pee. Believe it or not I usually wash chassis when they get very dirty, TSP is very good and getting rid of dirt and oxidation in things. The problems you are having with this 42-761EZ are precisely the sort of problems I would expect to find in that rusty 38-690 that was on fleabay, except that one had evidence of some very pitted aluminum parts as well as rust.
Regards
Arran
Posts: 13,776
Threads: 580
Joined: Sep 2005
City: Ferdinand
State, Province, Country: Indiana
I think you're absolutely right, Arran.
Let's consider which components are band specific - and that would be only the trimmers for each of the five "spread bands" (31M, 25M, 19M, 16M, 13M). So whatever is causing 31M to not operate properly - and causing 25M to not work at all - must be limited to components for those individual bands, and that leaves the trimmers for those bands.
The permeability tuning for those five bands use the same coils; different trimmers are switched in by the band switch in parallel with these coils to make it work on the different bands.
It's beginning to look like I am going to have to remove the RF assembly, which appears to be removable - but does not look to be an easy task.
--
Ron Ramirez
Ferdinand IN
Posts: 7,285
Threads: 268
Joined: Dec 2009
City: Roslyn Pa
D Grimes speaking from the grave!!!
Terry
Posts: 1,703
Threads: 55
Joined: Sep 2005
City: Evanston, IL
Sounds like you have the culprits in sight...and remember Ron, no good deed goes unpunished.
Murphy
Posts: 13,776
Threads: 580
Joined: Sep 2005
City: Ferdinand
State, Province, Country: Indiana
--
Ron Ramirez
Ferdinand IN
Posts: 1,703
Threads: 55
Joined: Sep 2005
City: Evanston, IL
"Mr. Crusher, please take us out of orbit...one quarter impulse"
![[-]](https://philcoradio.com/phorum/images/bootbb/collapse.png "[-]")
