[ARC5] Low B+ supplies for BC-454-B RX?

[WF2U]

The low B+ voltage in standard metal-octal tubes is used by the Russian
R250M HF receiver.

This model receiver used to be the top intercept receiver used by the
Soviets in the early fifties, (although the first model came out in 1949)
utilizing 23 metal octal tubes, all of them equivalent to the standard US
military types. The receiver is double conversion, with the first IF a
variable IF with crystal conversion to the whole HF range, in 2 MHz ranges,
similar to the Collins system (just different ranges). The receiver uses 160
VDC for the B+ supply. It's the best octal tubed receiver I ever used...

Other examples of low B+ voltage in receivers is the R-392 and R-808, where
the B+ is 24 VDC.

73, Meir WF2U
Landrum, SC


> -----Original Message-----
> From: arc5-bounces at mailman.qth.net
> [mailto:arc5-bounces at mailman.qth.net]On Behalf Of Kenneth G. Gordon
> Sent: Sunday, April 09, 2006 1:30 PM
> To: ARC5 at mailman.qth.net
> Subject: Re: [ARC5] Low B+ supplies for BC-454-B RX?
>
>
> On 9 Apr 2006 at 14:34, Roger Basford wrote:
>
> > I believe that it's quite feasible to run a BC-454, etc from a 50
> > volts B+ supply, is this correct?
>
> Yes. Quite correct. Many of us run them on 24 VDC to save having to
> replace those pesky can-type capacitors, especially C-16.
>
> However, in my case, I have found that the voltage at which they exhibit
> NO differences in the way they operate is about 180 VDC. To me, that
> is their optimum operating voltage. In my case, I determined that the
> optimum voltage could be further reduced if one made modifications to
> the screen circuit voltage-divider, reducing the difference between
> screen voltage and plate voltage.
>
> 250 VDC is, IMHO, way too high and totally unnecessary. It stresses
> everything too much, and most of it is wasted as unnecessary heat. I,
> personally, don't think ANY receiver should be run on 250 VDC or
> higher.
>
> In any case, our ARC-5s are no longer operating in a noisy, vibrating,
> refrigerator, in a near-vacuum.