[Milsurplus] "Correct" fuses for BC-342??

[W7QHO at aol.com]

In a message dated 5/21/2004 2:50:24 PM Eastern Daylight Time, WA5CAB at cs.com writes:

> 
> The correct fuses are 10 amp 25 or 32 volt.  Hot filament current is about 
> 1.3 amps.  At turn-on, probably twice that.  I'd check C78 and C79 and the 
> filament wiring.  Remember that if the RA-20 is connected to the radio, C79 will 
> show low resistance to ground through the filament winding (center tap is 
> grounded).
> 
> The BC-312 and BC-342 both use the same front panel fuses.  In the BC-312, 
> the DM-21 also runs off of the filament fuse, which is why 
> it is labeled 
> DYN-FIL.

Robert is correct but there are a couple of interesting side issues here.  Makes sense to use a 10 amp DYN-FIL fuse on the BC-312s but always seemed strange to me that a fuse with the same rating was retained in the 342.  The LAMPS fuse is also rated at 10 amps but the circuit only drives a pair of pilot lights. In early sets (312 and 342) this fuse also provided current to the oscillator compartment heaters which might explain the original rating.  On the 312s this circuit is also wired out to the 3-way SPEAKER SECOND AUDIO jack to run early speaker field coils. Both features (heaters and field coils) were dropped early on but the fuse rating was not changed.

Dennis D.  W7QHO
Glendale, CA