[ARC5] BC453 on 24V - screen voltage

[CARL HUETHER]

National made provisions to operate a lot of their AC equipment on a wide range of line voltages plus a battery pack/vibrator. This was due to their use all over the world where a steady voltage was often rare.
James Millen authored a QST page in the 30's about using the original HRO on reduced B+ and the improvement in sensitivity. Due to steady upheaval at National that didnt really click until the NC-300 when the concept was rediscovered!!

Carl
National Radio 1963-69


> On December 10, 2019 at 5:11 PM "Kenneth G. Gordon" <kgordon2006 at frontier.com> wrote:
> 
> 
> On 10 Dec 2019 at 21:07, Hubert Miller wrote:
> 
> > I was surprised to read in some National Radio Co. receiver manuals -
> > HRO-60 and  others - that the allowance for B+ was -50%. In this
> > particular receiver, 270 to 135 volts, without change. If possible, I
> > prefer to run at the lowest figure. Less heat, less stress.
> 
> I agree.
> 
> > Some
> > military radios run the B+ quite high, like I think the TRC-10 at 300
> > volts. Some few ham radios do too, and I'm thinking those are mostly
> > mobile equipment. One thing I have admired about post-WW2 Japanese
> > shortwave and ham radios is that they tend to use "calm" B+ voltages,
> > like in the 120 - 150 volt range. -Hue
> 
> I have mentioned this next before concerning that issue: some time ago, like eons, I read an 
> article in, I think, CQ Magazine, wherein the author experimented with reducing the DC 
> operating voltage in a Drake 2-B receiver to see what would happen.
> 
> He found that the receiver still worked adequately at 12 VDC, although, as expected, audio 
> output power was severely reduced.
> 
> He commented especially on how little apparent receiver noise there was at lower voltages.
> 
> He finally raised that voltage to about 50 VDC and left it there.
> 
> As I have mentioned, in my case, I found that with the "ARC-5" receivers, about 170 VDC 
> was the "best", since at that voltage audio output power remained "high". Otherwise, it 
> dropped off rather drastically.
> 
> RF and IF operation did not seem to be effected at all at even lower voltages.
> 
> Ken W7EKB
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