[Milsurplus] BC-348 Schematic ( Milsurplus Digest, Vol 135, Issue 8 )

[Hue Miller]

Some years back, possibly appearing in the small journal “Antique Radio Classifieds”,
someone was offering for what they touted as the first, modern rationalized redrawing
of the 348 schematic. I know that fact doesn’t do you much good. There was a USAF 
training manual on, I think, “Receivers” or “AM Transmitters and Receivers” which also
has a ‘modernized’, nice and clear looking schematic. I have the manual “somewhere”
but cannot look for it. Perhaps someone else here has it, or perhaps Robert Downs 
can cite you the exact TO number, and you could hunt it down, if you really really 
don’t like working with the original drawing.
I do think that many military manual schematics are just not that wonderful.
Maybe, I thought, I’d someday get around to redrawing some, such as the BC-654 
and No.19 set.
You know of course you don’t need a flat 220 volts and no less. I wouldn’t rewire the
fils either; I consider that a bad use of time, and maybe dumb besides, considering 
how easy it is to find 24 volt transformers. Some of the National Radio Co. receiver
manuals talk about running on batteries and surprisingly, to me, even such a well-
established company advised that their receiver B+, in one example, could be run
on 135 volts battery, down from the AC mains supplied B+ of about 250.
I’d look at hamfests for a transformer or some chassis that held such an item.
How many amps do you need at 24 volts?  I don’t know exactly where they are
hiding right now, but I have some nice 24 volt transformers. 
Oh, and place the supply outboard.
One notable example of outmoded schematic standards is the Navy CMS schematic.
This set, dating from somewhere in 1940-1945 ( on one seems to know for sure ) has
a schematic which shows the vacuum tube symbol with an actual rectangle for the 
plate, like, say 1925. Or maybe the idea was that you might have to build a replacement
tube, and you’d need to know what a plate looked like.
-Hue Miller