Steve:

I'm sure the hum is simply mechanical.  I'm also quite positive that the hum
is not due to anything like bad filter caps or poor voltage regulation.The
supply seems very stable in those regards, after a number of dummy load
tests I did earlier this evening.  I also had a 40-meter CW qso with an
experienced CW operator from Kansas who said that my tone was extremely
clear and clean.

May try the foam rubber approach, although, as you say, I'm going to have to
be careful that I don't block adequate air circulation.

Other than this, I don't think I'll do anything inside the supply
itself--not worth the trouble and the risk of voiding the one-year warranty.

Tom Behler: KB8TYJ






-----Original Message-----
From: For blind ham radio operators [mailto:[log in to unmask]]
On Behalf Of Steve Dresser
Sent: Friday, December 11, 2015 9:59 PM
To: [log in to unmask]
Subject: Re: Question on New RS35 Metered Power Supply

Tom,

I'm pretty sure that the hum is mechanical, caused by vibrations of the
transformer inside the supply being amplified by the metal case.  You might
try placing the supply on a thick piece of foam, keeping in mind that you
don't want the four feet to sink too deeply into the foam, which would block
circulation and probably give you a problem that would make you long for the
good old days when you were being annoyed by the hum.  I suppose you could
open the supply up and try to isolate the transformer from the case, but
that sounds like a lot of work, and I don't think you'll get much for your
efforts.  Bottom line: don't worry about the hum as long as it's not the
result of bad filter caps or poor voltage regulation (and from what you've
said, I don't think it is).

Steve

----- Original Message -----
From: "Tom Behler" <[log in to unmask]>
To: <[log in to unmask]>
Sent: December 11, 2015 20:45
Subject: Question on New RS35 Metered Power Supply


> Hi, everyone.
>
>
>
> Well, I got my new Astron RS35 metered linear power supply yesterday, and
> set it up tonight here in my home shack.
>
>
>
> Everything seems to work well, in that I get the output power readings I
> would expect on resonant HF frequencies via my TS590, and on VHF/UHF
> frequencies via my TMV71A.
>
>
>
> I have noticed something, though, that I could use some input on.
>
>
>
> For some reason, this new RS35 has a bit of a louder hum than I noticed 
> with
> my older unit.
>
>
>
> Has anyone noticed this sort of thing with the newer RS35's, and if so, 
> were
> you able to do anything to address the issue?
>
>
>
> I might consider moving the supply to another location, because right now,
> it is on a shelf just above my operating position.  However, I will need 
> to
> be certain that the newer location gives the supply sufficient space for
> ventilation.
>
>
>
> I am not sure the problem is significant enough to return it to HRO, but I
> would be curious if anyone has had a similar experience, at least 
> recently.
>
>
>
> Tom Behler: KB8TYJ
>
>