I have the same problem with the way rotary switches are presented on Drake schematics. If possible have a large size print made of the schematic and use colored pencils or a hi-liter to trace through the connections. I use the same technique on other schematics that look like maps of a freight yard.
toggle quoted message
Show quoted text
On 6/24/2022 1:04 PM, wb6ogd wrote:
Steve,
Sorry, I was looking at my R-4B schematic.
Disclaimer.. I am somewhat "Drake rotary switch" challenged...
The way I think it works is...
Power for the BFO or the AM detector comes from R130.
When the BFO should be on, this power is switched to T11/C163.
When in AM, power from R130 gets switched to R116.
So, I would check for voltage at T11 with the switch rotated.
C188 seems to be added to the same BFO circuit in the R-4B.
It decouples the exact node you propose to put a 1K to ground!!
Might be something Drake discovered in later models??
Also, schematic 919664054 seems to have a big error in the BFO, my downloaded from somewhere
copy has the correction marked in, that makes it like the R-4B schematic (the emitter connects to C163).
73,
Gary
WB6OGD
--
Richard Knoppow
1oldlens1@...
WB6KBL
