[ARC5] Receiver AC Power Supplies - lower voltage B+

[Bill Cromwell]

Hi Ken,

I didn't move anything on mine but I have powered them from a series 
pile of 9 volt batteries for ~180 volts. I was more interested in 
whether they worked or not worked but they did seem to be quieter 
running on batteries. I didn't tap those batteries very long. 9-volt 
batteries are rather wimpy (low amp-hours). Giving the power line crud 
the evil eye again.

73,

Bill  KU8H


On 12/13/2014 06:30 PM, Kenneth G. Gordon wrote:
> On 13 Dec 2014 at 10:20, DSP3 wrote:
>
>> Tell you what Mike... I've not seen (but not tried, either) on the
>> National but I have noticed that exact phenomena on ARC-5/274-N
>> receivers at about 160v or so B+.  Curious???
>>
>> Jeep - K3HVG
> I discovered some time ago that MY "ARC-5" receivers "seemed" to work
> much better at 170 - 180 VDC.
>
> I concluded that +170 VDC was optimal and mentioned that fact here some
> time ago, when the discussion at the time concerned running them at lower
> voltages...down to +24 VDC.
>
> At the 170-180 VDC level, they were both far cooler, and, what to me was
> more important, FAR quieter. S/N ratio appeared to be very noticeably
> improved.
>
> I also found that, when doing this, increasing the screen voltage on the
> RF and IF amps to 170 VDC also made a huge difference in operation. All
> that takes is moving one wire from the junction of R-22 and R-23 to the
> "hot" end.
>
> I did not experiment with attempting to find the optimal relationship
> between plate and screen voltages, although I'll bet there is such.
>
> The only side effect from using the lower voltage was about 1/2 the
> normal audio output level.
>
> YMMV.
>
> Ken W7EKB
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