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OT: Astron RS-35M Transformer Hum

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David Herring

OT: Astron RS-35M Transformer Hum

Does anyone have a way to dampen the physical hum generated by the transformer in an RS-35M PS?

This really is just transformer hum I’m hearing, not signal hum…my station is fully bonded and as a result quiet in that regard. Most folks probably never hear this hum, but I have been “blessed” with really good hearing and so this hum irritates the dickens out of me.

If push comes to shove, I will relocated the PS farther away from the operating position, I just didn’t want to have to extend power and bonding runs and thus am hoping someone has a different idea.

Thanks & 73,
David N5DCH
(Formerly AH6TD)

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Barry

Re: OT: Astron RS-35M Transformer Hum

Fairly common. I have a different Astron linear supply and have had that
issue. Make sure the cabinet and transformer screws are tight. Assuming
there's a relatively small gap between the top of the transformer and the
top of the case, stick something between the two surfaces (folded piece of
paper, for example) to dampen the induced vibration.

Barry W2UP

Does anyone have a way to dampen the physical hum generated by the
transformer in an RS-35M PS?

This really is just transformer hum I’m hearing, not signal hum…my station
is fully bonded and as a result quiet in that regard. Most folks probably
never hear this hum, but I have been “blessed” with really good hearing and
so this hum irritates the dickens out of me.

If push comes to shove, I will relocated the PS farther away from the
operating position, I just didn’t want to have to extend power and bonding
runs and thus am hoping someone has a different idea.

Thanks & 73,
David N5DCH
(Formerly AH6TD)

--
Sent from: http://elecraft.365791.n2.nabble.com/
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David Bunte

Re: OT: Astron RS-35M Transformer Hum

In reply to this post by David Herring

David -

I have an RS-35M, that sits on a shelf under my operating desk. I leave it
on 24/7, and never gave any thought to acoustic hum from it. I just ducked
my head down below the desktop, and 'thought' I could hear some hum. I
turned off the power supply and verified that there is a little bit that I
could detect. I am blessed with better than average hearing for a
76-year-old, but that is largely thanks to my hearing aids.

In the past I have had pretty bad hum from power supply transformers, and
the worst case I ever had was totally cured by tightening the bolts that
held the laminations together. That was pretty easy because it was an open
frame transformer in a home brew KW amp. In a number of transformers I have
paid attention to in the past few years, the screws or bolts that hold the
transformer to the chassis go through the corners of the laminations, and
tightening those may also help.

I have been "told" that acoustic hum is often made more evident because the
chassis is vibrating... and that putting some dampening material (a sheet
of rubber for example) under the transformer goes a long way toward
reducing the problem.

Best of luck.

Dave - K9FN

On Fri, Apr 24, 2020 at 10:14 AM David Herring <[hidden email]>
wrote:

> Does anyone have a way to dampen the physical hum generated by the
> transformer in an RS-35M PS?
>
> This really is just transformer hum I’m hearing, not signal hum…my station
> is fully bonded and as a result quiet in that regard. Most folks probably
> never hear this hum, but I have been “blessed” with really good hearing and
> so this hum irritates the dickens out of me.
>
> If push comes to shove, I will relocated the PS farther away from the
> operating position, I just didn’t want to have to extend power and bonding
> runs and thus am hoping someone has a different idea.
>
> Thanks & 73,
> David N5DCH
> (Formerly AH6TD)
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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Robert Sands

Re: OT: Astron RS-35M Transformer Hum

My Astron hums loudly only when the fax machine runs. Otherwise silent.
?interaction puzzling.

On Fri, Apr 24, 2020, 7:35 AM David Bunte <[hidden email]> wrote:

> David -
>
> I have an RS-35M, that sits on a shelf under my operating desk. I leave it
> on 24/7, and never gave any thought to acoustic hum from it. I just ducked
> my head down below the desktop, and 'thought' I could hear some hum. I
> turned off the power supply and verified that there is a little bit that I
> could detect. I am blessed with better than average hearing for a
> 76-year-old, but that is largely thanks to my hearing aids.
>
> In the past I have had pretty bad hum from power supply transformers, and
> the worst case I ever had was totally cured by tightening the bolts that
> held the laminations together. That was pretty easy because it was an open
> frame transformer in a home brew KW amp. In a number of transformers I have
> paid attention to in the past few years, the screws or bolts that hold the
> transformer to the chassis go through the corners of the laminations, and
> tightening those may also help.
>
> I have been "told" that acoustic hum is often made more evident because the
> chassis is vibrating... and that putting some dampening material (a sheet
> of rubber for example) under the transformer goes a long way toward
> reducing the problem.
>
> Best of luck.
>
> Dave - K9FN
>
>
>
> On Fri, Apr 24, 2020 at 10:14 AM David Herring <[hidden email]>
> wrote:
>
> > Does anyone have a way to dampen the physical hum generated by the
> > transformer in an RS-35M PS?
> >
> > This really is just transformer hum I’m hearing, not signal hum…my
> station
> > is fully bonded and as a result quiet in that regard. Most folks
> probably
> > never hear this hum, but I have been “blessed” with really good hearing
> and
> > so this hum irritates the dickens out of me.
> >
> > If push comes to shove, I will relocated the PS farther away from the
> > operating position, I just didn’t want to have to extend power and
> bonding
> > runs and thus am hoping someone has a different idea.
> >
> > Thanks & 73,
> > David N5DCH
> > (Formerly AH6TD)
> >
> >
> > ______________________________________________________________
> > Elecraft mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:[hidden email]
> >
> > This list hosted by: http://www.qsl.net
> > Please help support this email list: http://www.qsl.net/donate.html
> > Message delivered to [hidden email]
> ______________________________________________________________
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Robert Sands
K7VO
Olympia, WA

John Simmons

Re: OT: Astron RS-35M Transformer Hum

My laser printer has the same effect.

-de John NI0K

Robert Sands wrote on 4/24/2020 10:17 AM:

> My Astron hums loudly only when the fax machine runs. Otherwise silent.
> ?interaction puzzling.
>
> On Fri, Apr 24, 2020, 7:35 AM David Bunte <[hidden email]> wrote:
>
>> David -
>>
>> I have an RS-35M, that sits on a shelf under my operating desk. I leave it
>> on 24/7, and never gave any thought to acoustic hum from it. I just ducked
>> my head down below the desktop, and 'thought' I could hear some hum. I
>> turned off the power supply and verified that there is a little bit that I
>> could detect. I am blessed with better than average hearing for a
>> 76-year-old, but that is largely thanks to my hearing aids.
>>
>> In the past I have had pretty bad hum from power supply transformers, and
>> the worst case I ever had was totally cured by tightening the bolts that
>> held the laminations together. That was pretty easy because it was an open
>> frame transformer in a home brew KW amp. In a number of transformers I have
>> paid attention to in the past few years, the screws or bolts that hold the
>> transformer to the chassis go through the corners of the laminations, and
>> tightening those may also help.
>>
>> I have been "told" that acoustic hum is often made more evident because the
>> chassis is vibrating... and that putting some dampening material (a sheet
>> of rubber for example) under the transformer goes a long way toward
>> reducing the problem.
>>
>> Best of luck.
>>
>> Dave - K9FN
>>
>>
>>
>> On Fri, Apr 24, 2020 at 10:14 AM David Herring <[hidden email]>
>> wrote:
>>
>>> Does anyone have a way to dampen the physical hum generated by the
>>> transformer in an RS-35M PS?
>>>
>>> This really is just transformer hum I’m hearing, not signal hum…my
>> station
>>> is fully bonded and as a result quiet in that regard. Most folks
>> probably
>>> never hear this hum, but I have been “blessed” with really good hearing
>> and
>>> so this hum irritates the dickens out of me.
>>>
>>> If push comes to shove, I will relocated the PS farther away from the
>>> operating position, I just didn’t want to have to extend power and
>> bonding
>>> runs and thus am hoping someone has a different idea.
>>>
>>> Thanks & 73,
>>> David N5DCH
>>> (Formerly AH6TD)
>>>
>>>
>>> ______________________________________________________________
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:[hidden email]
>>>
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>> Message delivered to [hidden email]
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email]
> ______________________________________________________________
> Elecraft mailing list
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>
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Elecraft mailing list

Re: OT: Astron RS-35M Transformer Hum

In reply to this post by Robert Sands

I have an Astron RS-35A, and also hums, not too loud, but if the Shack is in silence, I can hear it, low but can be heard.
73 to all,
Fernando, PY1BL

Sent from my iPhone

> On Apr 24, 2020, at 12:17 PM, Robert Sands <[hidden email]> wrote:
>
> My Astron hums loudly only when the fax machine runs. Otherwise silent.
> ?interaction puzzling.
>
>> On Fri, Apr 24, 2020, 7:35 AM David Bunte <[hidden email]> wrote:
>>
>> David -
>>
>> I have an RS-35M, that sits on a shelf under my operating desk. I leave it
>> on 24/7, and never gave any thought to acoustic hum from it. I just ducked
>> my head down below the desktop, and 'thought' I could hear some hum. I
>> turned off the power supply and verified that there is a little bit that I
>> could detect. I am blessed with better than average hearing for a
>> 76-year-old, but that is largely thanks to my hearing aids.
>>
>> In the past I have had pretty bad hum from power supply transformers, and
>> the worst case I ever had was totally cured by tightening the bolts that
>> held the laminations together. That was pretty easy because it was an open
>> frame transformer in a home brew KW amp. In a number of transformers I have
>> paid attention to in the past few years, the screws or bolts that hold the
>> transformer to the chassis go through the corners of the laminations, and
>> tightening those may also help.
>>
>> I have been "told" that acoustic hum is often made more evident because the
>> chassis is vibrating... and that putting some dampening material (a sheet
>> of rubber for example) under the transformer goes a long way toward
>> reducing the problem.
>>
>> Best of luck.
>>
>> Dave - K9FN
>>
>>
>>
>> On Fri, Apr 24, 2020 at 10:14 AM David Herring <[hidden email]>
>> wrote:
>>
>>> Does anyone have a way to dampen the physical hum generated by the
>>> transformer in an RS-35M PS?
>>>
>>> This really is just transformer hum I’m hearing, not signal hum…my
>> station
>>> is fully bonded and as a result quiet in that regard. Most folks
>> probably
>>> never hear this hum, but I have been “blessed” with really good hearing
>> and
>>> so this hum irritates the dickens out of me.
>>>
>>> If push comes to shove, I will relocated the PS farther away from the
>>> operating position, I just didn’t want to have to extend power and
>> bonding
>>> runs and thus am hoping someone has a different idea.
>>>
>>> Thanks & 73,
>>> David N5DCH
>>> (Formerly AH6TD)
>>>
>>>
>>> ______________________________________________________________
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:[hidden email]
>>>
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>> Message delivered to [hidden email]
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email]
> ______________________________________________________________
> Elecraft mailing list
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>
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> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

Eric Garner

Re: OT: Astron RS-35M Transformer Hum

Has anyone tried using something like Dynamat (used to damp vibrations in
cars). To keep the case from resonating?

On Fri, Apr 24, 2020 at 9:17 AM Fernando Sindeaux via Elecraft <
[hidden email]> wrote:

> I have an Astron RS-35A, and also hums, not too loud, but if the Shack is
> in silence, I can hear it, low but can be heard.
> 73 to all,
> Fernando, PY1BL
>
> Sent from my iPhone
>
> > On Apr 24, 2020, at 12:17 PM, Robert Sands <[hidden email]> wrote:
> >
> > My Astron hums loudly only when the fax machine runs. Otherwise silent.
> > ?interaction puzzling.
> >
> >> On Fri, Apr 24, 2020, 7:35 AM David Bunte <[hidden email]> wrote:
> >>
> >> David -
> >>
> >> I have an RS-35M, that sits on a shelf under my operating desk. I leave
> it
> >> on 24/7, and never gave any thought to acoustic hum from it. I just
> ducked
> >> my head down below the desktop, and 'thought' I could hear some hum. I
> >> turned off the power supply and verified that there is a little bit
> that I
> >> could detect. I am blessed with better than average hearing for a
> >> 76-year-old, but that is largely thanks to my hearing aids.
> >>
> >> In the past I have had pretty bad hum from power supply transformers,
> and
> >> the worst case I ever had was totally cured by tightening the bolts that
> >> held the laminations together. That was pretty easy because it was an
> open
> >> frame transformer in a home brew KW amp. In a number of transformers I
> have
> >> paid attention to in the past few years, the screws or bolts that hold
> the
> >> transformer to the chassis go through the corners of the laminations,
> and
> >> tightening those may also help.
> >>
> >> I have been "told" that acoustic hum is often made more evident because
> the
> >> chassis is vibrating... and that putting some dampening material (a
> sheet
> >> of rubber for example) under the transformer goes a long way toward
> >> reducing the problem.
> >>
> >> Best of luck.
> >>
> >> Dave - K9FN
> >>
> >>
> >>
> >> On Fri, Apr 24, 2020 at 10:14 AM David Herring <[hidden email]>
> >> wrote:
> >>
> >>> Does anyone have a way to dampen the physical hum generated by the
> >>> transformer in an RS-35M PS?
> >>>
> >>> This really is just transformer hum I’m hearing, not signal hum…my
> >> station
> >>> is fully bonded and as a result quiet in that regard. Most folks
> >> probably
> >>> never hear this hum, but I have been “blessed” with really good hearing
> >> and
> >>> so this hum irritates the dickens out of me.
> >>>
> >>> If push comes to shove, I will relocated the PS farther away from the
> >>> operating position, I just didn’t want to have to extend power and
> >> bonding
> >>> runs and thus am hoping someone has a different idea.
> >>>
> >>> Thanks & 73,
> >>> David N5DCH
> >>> (Formerly AH6TD)
> >>>
> >>>
> >>> ______________________________________________________________
> >>> Elecraft mailing list
> >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> >>> Help: http://mailman.qth.net/mmfaq.htm
> >>> Post: mailto:[hidden email]
> >>>
> >>> This list hosted by: http://www.qsl.net
> >>> Please help support this email list: http://www.qsl.net/donate.html
> >>> Message delivered to [hidden email]
> >> ______________________________________________________________
> >> Elecraft mailing list
> >> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> >> Help: http://mailman.qth.net/mmfaq.htm
> >> Post: mailto:[hidden email]
> >>
> >> This list hosted by: http://www.qsl.net
> >> Please help support this email list: http://www.qsl.net/donate.html
> >> Message delivered to [hidden email]
> > ______________________________________________________________
> > Elecraft mailing list
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>
> ______________________________________________________________
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Re: OT: Astron RS-35M Transformer Hum

My 50 Amp Astron had a piece of cork material glued between the front of the case and the transformer. It started humming one day when the glue dried out and the cork fell. I glued it back in place and all is well.

I had a 70 Amp do the same thing.

Maybe try a little piece of some similar material between the side of the case and transformer.

Hank
K4HYJ

----- Original Message -----
From: Eric Garner ([hidden email])
Date: 04/24/20 12:57
To: Elecraft Discussion List ([hidden email])
Subject: Re: [Elecraft] OT: Astron RS-35M Transformer Hum

Has anyone tried using something like Dynamat (used to damp vibrations in
cars). To keep the case from resonating?

On Fri, Apr 24, 2020 at 9:17 AM Fernando Sindeaux via Elecraft <
[hidden email]> wrote:

--
--Eric
_________________________________________
Eric Garner
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David Herring

Re: OT: Astron RS-35M Transformer Hum

In reply to this post by Eric Garner

I just got the PS back together and online again. I was astounded to discover that the transformer bolts were actually just shy of hand tight. I tightened them up and found that that quieted the thing down a lot. Not completely, but to a very large extent.

The bolts holding the transformer to the chassis were already tight, but I loosened and retightened them anyway, JIC.

Testing with a cardboard shim between the transformer and the lid didn’t make a difference in this case, but I thought it worth a shot anyway.

I scoured the shack and the junque box and didn’t find anything such as rubber or anything else suitable for use a dampener under the transformer, so figured that could wait. But I did perform some more experiments and discovered that the desk itself was exacerbating the noise more than I realized. So, it took some doing but I managed to move the PS under the desk sitting on cinder blocks. I didn’t have to lengthen the power run or the ground doing it this way, and it’s now sitting on something with mass so that there is virtually no vibration transfer anywhere.

Happy to report the thing is as quiet as a church mouse now. ;-)

Thanks everyone…some really good information here…

David, N5DCH
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Jim Brown-10

Re: OT: Astron RS-35M Transformer Hum

In reply to this post by Robert Sands

On 4/24/2020 8:17 AM, Robert Sands wrote:
> My Astron hums loudly only when the fax machine runs. Otherwise silent.
> ?interaction puzzling.

This strongly suggests one or more mis-wired outlets in your home.
Things like phase (hot) and neutral reversal, neutral and ground
reversal, or an additional bond between neutral and ground (there MUST
be one at the power entry panel, but there must NOT be one anywhere else).

I suggest that you start by checking every outlet with a good outlet
tester.

There's one other thing about Astron supplies that also might be the
cause -- the green wire is not properly connected to the chassis inside
the PSU, because the lug to which the green wire is soldered is
insulated from the chassis by paint. Check for this by measuring between
the green wire on the plug and the chassis with an Ohmmeter. You should
see a dead short. If you don't, open it up, scrape the paint under that
lug. While you're at it, remove the wire between V- and that lug. This
problem is documented in
http://k9yc.com/PowerSupplyBondingAndAudioDistortion.pdf

73, Jim K9YC
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