Lou:

Steve (KW3A) has suggested a similar approach, and I will give it a try.

Again, I don't consider this to be a major problem--just a bit annoying.

The supply itself seems to work great, so at least I'm making progress.

Thanks for the suggestion.

Tom Behler: KB8TYJ


-----Original Message-----
From: For blind ham radio operators [mailto:[log in to unmask]]
On Behalf Of Lou Kolb
Sent: Saturday, December 12, 2015 7:35 AM
To: [log in to unmask]
Subject: Re: Question on New RS35 Metered Power Supply

Tom,

I've had occasions where hum was caused by the 2 parts of the case vibrating
against each other. The solution here is to wedge a small piece of cardboard
or something else between the top cover and the front or side panels as a
kind of isolater. Just a thought. Lou Lou Kolb Voice-over Artist:
Radio/TV Ads, Video narrations
Messages On-hold:
www.loukolb.com
----- Original Message -----
From: "Tom Behler" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, December 11, 2015 10:15 PM
Subject: Re: Question on New RS35 Metered Power Supply


> 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
>>
>>