On the surface, the two transmitters appear to be identical. They are 95% identical with the following differences noted.
- The BC-191 uses the BD-77M
dyamotor with a 12 volt 52 ampere input, while the BC-375 uses the PE-73C dyamotor with
a 26 volt 20 ampere input.
- The BC-191's
tube filaments are all parallel fed from the 12 volt source through
dropping resistors. The BC-375 tube filaments are
arranged in three series strings (i.e. MOPA tubes, modulator tubes and
speech amplifier/sidetone tube) that are parallel fed by a 26
volt source through
dropping resistors.
- The
BC-191 uses an antenna relay with a 12 volt coil, while the BC-375 uses an antenna relay with a 24
volt coil
- The BC-375
has an antenna terminal block on the upper right side with 5 connections
(Antenna, Ground, Receiver, Load A, Load B). The BC-191 has its antenna
block on the top right side with 6 connections. The extra connection is
called CPSE and is connected to the RF ammeter and the variable capacitor
"O" (when the mode select switch "N" is in position #1). These connections
would go directly to ground on the BC-375E. On the BC-191, the CPSE post can be
either connected to the ground post for some applications or the CPSE connection could be used in
for static ground stations (which used a 1/4 wave length wire antenna,
this required a ground counterpoise, usually a 1/4 wave bit of wire laid
under the antenna) .
- The BC-375 has three connectors on
the left side (PL-61: low voltage & dynamotor control, PL-59: high
voltage and PL-64: junction box). The BC-191 has an additional connector
PL-74 used in some vehicular applications
( e.g. the M3A1 scout car which had a control box in the cable harness) .
The SCR 193 was used in the following vehicles
- 193A Light
tank M2A3
- 193B Scout
car M3
- 193C Combat
car M1A1
- 193D Scout
car M3A1
- 193E Dodge
1/2 ton command radio truck
- The
BC-191 has a separate jack for the microphone and telegraph key, while
the BC-375 uses a common jack for both.
Special thanks
to Mike, VK3CZ, for providing the information in bullets 4) and 5)
For more BC-375 information,
click on the following links.