Years ago, I recovered a very heavily
damaged KWM-2 from a scrap yard.
When I started harvesting the usable parts, I found a wire top a
tube socket that was crimped, no solder and the red inspection
paint on the connection.
I guess this was the reason the radio was scrapped.
It probably worked for a while.
73
Glenn
WB4UIV
On 1/25/2024 7:12 AM, David Stinson
wrote:
Every
few days, I get a little time to work on this WWII
German Torn E.b receiver. Been fixing the damage done
by someone trying to re-tube it, but there are other,
more interesting things in here.
First- This radio could never have functioned.
These solder joints are obviously original, but
the primary power wiring, B+, B- and Filament
are all hosed-up from the power connector to the
power switch and from there to the receiver circuits.
I replaced the missing tube socket, repaired the
filament circuits, then replaced a couple of bad
resistors fried by having B+ between them and ground.
Tested the B+/B- buss for shorts/leakage. It looked
OK so bypassed the bad wiring and connected
voltage to the busses for a first test.
Filament circuit looked OK except the audio tube's
filament was at 2.2V when the RF tubes were at 1.8V
That's going to be a Hi-Z ground somewhere.
Brought the B+ up slow and, touching the plate of
the 2nd RF tube produced a satisfying racket.
However, no such response from the 1st RF. Got
to measuring and I had no plate or screen voltage there.
On inspection, I found something odd- both the plate
and screen connections at the tube socket were carefully
placed and with "molded" solder to look like good
connections, but once the wires were moved aside,
neither connection had actually been made.
I should have take photos.
I wonder if it was just sloppy workmanship and
rubber-stamp inspection (not like the Germans
in 1943) or if some poor forced-labor person
did this intentionally. Guess we'll never know.
Not the first piece of gear I've found
"inop out of the box." RBB refurbished in
San Fran with some of the band switches put
back 180 degrees off, a ZM-11 bridge with
wires crossed, etc.
Have you seen factory/depot defects in your mil gear?
GL OM ES 73 DE Dave AB5S
--
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Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIV [email protected] AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI, FRA, NRA-LM ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"