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Author Topic: Astron 35 a Humming  (Read 3112 times)
N6SBN
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« on: March 26, 2013, 08:37:51 AM »


  Is there any cure for the audible humming noise coming from an Astron 35 power supply.   I vaguely remember an article about people tightening down the transformer to the chassis to solve this problem, though, I could be wrong.

Thanks in advance. 
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KD0REQ
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« Reply #1 on: March 26, 2013, 09:04:50 AM »

loose laminations in a standard EI core analog transformer are fairly common, and cause hum and vibration.  tightening down the bolts as they pass through the shells and laminations frequently provides relief.  occasionally the bobbin full of wire shakes loose of the core, and might need a wedge to keep it from vibrating.  and while you're fooling around there, tighten the transformer to cabinet fasteners.

if that doesn't do it, at least try to get it to hum in your own key, so you can sing along for the 40 to 50 years it will take for this to damage the transformer so you can replace it.
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KA4POL
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« Reply #2 on: March 26, 2013, 09:27:04 AM »

Try to locate the source of the hum by gently (!) pressing on the windings, the core etc. with a nonconductive part like a piece of wood or similar. From this you can tell what to do best.
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K8AXW
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« Reply #3 on: March 26, 2013, 09:34:56 AM »

BJW:

http://forums.qrz.com/archive/index.php/t-57472.html

http://www.repeater-builder.com/astron/astron-intro-stuff.html

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K8AC
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« Reply #4 on: March 26, 2013, 12:07:22 PM »

Often, the mechanical noise you hear from the Astrons is coming from the thin sheet metal cabinet.  When you're hearing the hum, put your hand on the cabinet top and press down lightly.  If the noise is substantially changed or reduced, the problem is that the steel cabinet is being affected by stray flux from the transformer.  One way to fix this is to damp the cabinet - something you'd normally do from the inside, but there's no room in the Astron to do that and the cabinet top can't be simply pulled straight up anyway.  The way it slides would prevent using damping material inside.  You could apply damping foam (adhesive backed) to the top of the cabinet on the outside and that would help a bit.  The foam can be obtained from a number of companies on the web who deal with quieting down noisy PCs. 

Another approach might be to take the steel cabinet top to a sheetmetal shop and have them bend an aluminum top for you.  I've had more noise problems with Astrons from this source than from loose transformer laminations or bolts.
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N4NYY
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« Reply #5 on: March 26, 2013, 01:36:01 PM »

I have a 35M that hums on transmit. Light hum, not bothersome. I just live with it.
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N6SBN
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« Reply #6 on: March 26, 2013, 09:25:32 PM »

The humm fills the room with this one.  I'll play with the cabinet.
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VE7REN
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« Reply #7 on: March 27, 2013, 04:19:27 AM »

i took the cover off mine and put a foam tape along the top faceplate where the cover comes in contact with it.. problem was solved
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KA3TRX
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« Reply #8 on: March 30, 2013, 10:21:01 AM »

Teach it the words?
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K1CJS
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« Reply #9 on: March 30, 2013, 10:49:02 AM »

Another method that sometimes works when the cabinet is at fault is to put some foam stripping on the top of the transformer, enough to make sure it is pressed down firmly when the cover is put back on.  That stops the vibration effect that is really what that hum may be. 
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WB6DGN
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« Reply #10 on: March 31, 2013, 02:10:23 PM »

Quote
Is there any cure for the audible humming noise coming from an Astron 35 power supply.

Teach it the words?
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K8AXW
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« Reply #11 on: March 31, 2013, 08:11:32 PM »

DGN:  I think what he means is if the humming is some song, teach it the words.  If it's simply random humming, there isn't anything you can do except listen to the hum.

Like Rosanna, Rosanna Danna used to say on Saturday Night Live, "Never mind!"   Roll Eyes

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KE7FD
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« Reply #12 on: April 01, 2013, 07:57:02 PM »

I have a RS-35M that's quiet as it was the day I bought it, but I needed another supply and understand that over time the (analog) power transformer can sometimes begin it's l-o-n-g journey to death by coming apart at the seams... As described above.  If the cost of replacing the beasty xformer outweighs the wallet, consider a good switching supply.  A while back I bought one of these and it's been great:

http://www.ebay.com/itm/36-Amp-12-Volt-13-8V-Regulated-Radio-Power-Supply-12V-/370416560359?pt=US_Radio_Comm_Device_Power_Supplies&hash=item563e8c28e7

At the time it was rated high on eHam (not sure what it was called then) and since there's been a steady increase in good quality switching supplies, you can find good quiet units easily today.

Personally I think the analog supplies are the best and having the dual meters is icing on the cake but if it costs too much to replace the main part inside, maybe look at a good switching unit.

imho,
Glen - KE7FD
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K8AXW
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« Reply #13 on: April 01, 2013, 09:08:26 PM »

Glen:  During the years I've prowled these eHam forums, especially "Elmers," answering questions about the Astron power supplies, I have never once heard of anyone needing to replace the transformer!  Some transformers do hum but never to the point of destruction.  In each case with some particular steps, the hum is eliminated or quieted down to the point where it becomes negligible.

Your observations on the switching power supplies are right on.  I have used a switching power supply for quite some time now and it's very quiet.  Switching power supplies have been evolving quite a bit the past few years with the manufacturers realizing that it's absolutely necessary to build them 'quiet!'

I also have an Astron, a Pyramid and a Kenwood power supplies.  No problems with any of them.



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KE7FD
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« Reply #14 on: April 02, 2013, 06:09:03 AM »

Allen, yup, me either.  Quite the visual though, a transformer falling apart. That being said though, I've seen plenty fry over the years although never in an Astron.  When it came time to buy a second supply I needed something compact and light for a grab and go setup.  In fact as I think about it I did have a smaller Astron but light weight was not part of its DNA, so I picked up the switching unit. Snug and quite I've packed the grab and go pack to at least one or two Field Days.

g
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