[Milsurplus] BC-312

[Kenneth G. Gordon]

On 25 Oct 2022 at 22:18, Glenn Little WB4UIV wrote:

> 
> I have a BC-312 that was modified by a previous owner.
> I think that he had an external power supply as there is a multi-conductor cable leaving 
> the radio and no dynamotor.
> What is the lowest HV that I can use and get good performance from the radio?

I don't know for sure about the BC-312, but I DO know that most receivers will work just fine 
with much lower B+ than was the original voltage.

ARC-5 receivers work best with about 170 VDC instead of 250 VDC, by my test. However, I 
had to move the screen voltage lead to the top of the series resistors in that circuit, i.e. 170 
VDC to get the best results.

The Navy used 180 VDC for the RAX series.

I own two BC-312/342 receivers here (both missing their fiducial, darn it), but have not yet 
fired them up so I don't know for certain what HV would work best with those.

> The radio is rated for 260 VDC at 95 mA.

Well, I very seriously doubt you would need 260 VDC. You might try 175 VDC, but check the 
circuit as you may have to increase the screen voltages to get maximum performance out of 
the receiver.

> The filament draw is listed at 3 A.
> If I can run this on reduced plate Voltage, would it be feasible to use a 12.6 Volt 
> transformer to feed the filaments and an inverter to provide the HV?

Hmmm...that sounds interesting. In any case, I would certainly try that.

> 
> Any thoughts, suggestions?
> The previous modifications are not easily reversible due to a large hole cut into the front 
> panel for an S meter.

Sigh... :-(

Well, we work with what we have.

Good luck.

Ken W7EKB