[Milsurplus] WWII Portable Regens

[Mike Morrow]

Dave, BC-186 is the receiver for SCR-178 and-179.  If you search the Radionerds site for SCR-178 it will take you to a page with a pdf link to the last manual for SCR-178 including BC-186...TM 11-231 12/1941.

SCR-178 operated only between 2.4 and 3.7 MHz.  Its BC-187-* transmitter uses a type 10 MO and type 865 PA, neither inexpensive.  It's all very early 1930's technology.  :-)

Mike / KK5F
-----Original Message-----
From: David Stinson <arc5 at ix.netcom.com>
Sent: Jan 1, 2024 11:54 AMERICA 

Been occasionally tinkering with
WWII Portable Regens.
Have a U.S. BC-186,
Japanese 94-5 and German Torn e.B.
The -185 and 94-5 are working and
the Torn is getting there.

Couple of questions:
Did the other major combatants-
U.K., USSR, France, Italy, China etc.
have similar and widely-deployed
portable regens?

The BC-186 has two plug-in coils.
My is 2400 KC to 3700 KC. I don't
have a complete manual for the 186.
Were other coil sets deployed?

All the caps and resistors were good.
Only thing needed was to trace the
non-original connector and use a quarter-
inch piece of heat-shrink to prevent a
a short between a coil's trimmer cap and
the coil case. Simple and nice-sounding.
https://photos.app.goo.gl/q5nfg7kZ5azUdVo89

The 94-5 is a little more "fiddly." I got
lucky and found a "parter" with a good
Audio Output transformer. I have fantasies
about finding a 94-5 transmitter for it.
Anyone want to trade a clean, working RS-6
station for a clean, complete 94-5 transmitter??
https://photos.app.goo.gl/fBfLzzwjnSEj6byY8

The Torn e.B is still "in progress."
Been trying to recover someone's failed
attempt at re-tubing the thing- they made
a big mess. Here is a photo of an "oddity."
https://photos.app.goo.gl/HJ95Er71RF3BNUfMA

One of the tube stages has
a wire-wound, adjustable resistor across
it's filament, the "slider" connecting
to a 2-Meg resistor which goes to the
signal grid of the tube. It is missing
in my set and the screw securing it is
broken-off in the chassis.

This area is very cramped and finding the
exact mini-Wire-Wound with tap seems unlikely.
The filaments are 2VDC.
This is a voltage divider directly across
this tube's filament,
so the most voltage at the tap possible is
2V, and give the photo in the manual
I assume this is a way to deliver
negative bias to the tube
without needing a "C" battery.
Maybe 1 V is all the bias it needs?

Given that 100 Ohms across 2 VDC is only
dissipating .04 Watts, I'm thinking a
small 100-ohm pot will sub until
a suitable original surfaces.
Any insights on this circuit?

TNX ES HPY NY OM DE Dave AB5S