[Elecraft] Power Supplies

[Richard Fjeld]

Kevin,
As I mentioned, I think this will depend on the Voltage Regulation level 
in the receiver.
The Elecraft gear operates down low in voltage pretty well.  I have 
experienced what
you describe with other gear I have owned,  but I have not compared if a 
difference is heard
when going from a lower battery voltage to a higher PS voltage with 
Elecraft gear.

I understand your problem is mainly with the RS-50.  If you don't have a 
scope, you
could put your DVM on AC and see if any AC can be measured on the 13.8 
DC output
terminals.  Try with, and without, some load. It's not a good test, but 
something to try.

BTW, my experience with talking to Astron has been very good. They will 
help you.

Dick, n0ce


On 7/15/2016 4:01 PM, Kevin - K4VD wrote:
> Thanks Dick and Howard...
>
> The RS-50 is pretty new - maybe 6 months old and is in daily use. It wasn't
> until I had a rig I could easily run on batteries did I notice the noise.
> The RS-12 is quite old, maybe 15 years? It had been in storage about 10
> years until trying it out today. I think I need to dig into the RS-50 and
> just make sure everything is soldered and connected well.
>
> As for common mode currents in the antenna... would that only be an issue
> during transmit? I have an OCF so I know it can be an issue on transmit.
> The OCF has a 1:1 current BALUN in the center. Is that enough or do I need
> to add some additional choking just below the BALUN? I have a couple of the
> NI4L line isolators (http://www.ni4l.com/hf-choke-line-isolator-1-8-300-mhz/).
> I could put one up there and see what it does. I also have plenty of
> clip-ons laying around. I'll try them on the power lead from the supply to
> the radio.
>
> The reports above were with *receive only* (with and without an antenna
> attached). On the RS-50 the hum I'm hearing is what I think I'd expect to
> hear from a less-that-well filtered linear power supply. The hash/hiss
> noise I hear sounds more like a switching power supply, which it is not. I
> don't know what in the power supply could be generating that noise.
>
> The RS-12 does not have either the hum or hiss that I can hear. It just
> sounds like the noise floor bumped up a little. I'm thinking Dick is right
> and it is just the receiver responding to the increased voltage though it
> is only about .5 volts above the external battery pack I was using.
>
> Is every power supply going to generate a little noise or should I expect
> no difference moving from battery to power supply?
>
> Kev
>