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Author Topic: Astron SS-30M noise  (Read 3572 times)
K7GDE
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Posts: 5




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« on: April 22, 2013, 06:58:49 PM »

I have had an Astron SS-30M power supply for many years mostly used with a Kenwood TM-D700. I just got my first HF radio IC-718 and found that the SS-30m adds noise on 40m. When the radio is powered off a battery the noise floor on 40m is S2 but when I connect it to the SS-30M it goes up to S7.

There is no noise from the power supply if the IC-718 is not connected while the supply powering the TM-D700 and other items, its only with the 718 connected. Its also only on 40m.

Any ideas on how to help kill the noise?

Jeff, K7GDE
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W5CPT
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Posts: 557




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« Reply #1 on: April 23, 2013, 06:40:00 AM »

A few things at which to look:

Does the Icom, Kenwood and the Astron share a common ground strap to the grounding point in your setup? If not, make it so.

Disconnect the antenna from the Icom and see if the noise goes away, or gets much less. This will tell you if the noise is getting into the HF rig by the power cable or the antenna port. *Note: do not transmit with the antenna disconnected.*  If the noise is diminished when the antenna is disconnected, make sure your grounding of the power supply is correct.  Correct = as short as possible - large enough conductor, preferably flat braid or strip rather than wire - solid (bonded if possible) connection to the ground rod -

If the noise IS coming in through the power cable, try straightening out the cable or winding it up (try different ways - coil or figure eight) and see if this makes a difference. If it does, the noise is ON the cable and if it doesn't the noise is IN the cable. If ON, try snap on ferrites, or threading the cable through a larger ferrite (going to be tough to find one large enough though).

If the noise is IN the cable, fixing it will be harder. The PS is obviously generating the noise at a low frequency (40M) that the VHF radio does not hear or detect.

Short of that (or anything else some one might add) consider dedicating that supply to your VHF and look for another supply for your HF.

Clint - W5CPT -
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K7GDE
Member

Posts: 5




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« Reply #2 on: April 23, 2013, 08:42:24 AM »

If the noise IS coming in through the power cable, try straightening out the cable or winding it up (try different ways - coil or figure eight) and see if this makes a difference. If it does, the noise is ON the cable and if it doesn't the noise is IN the cable. If ON, try snap on ferrites, or threading the cable through a larger ferrite (going to be tough to find one large enough though).

If the noise is IN the cable, fixing it will be harder. The PS is obviously generating the noise at a low frequency (40M) that the VHF radio does not hear or detect.

Short of that (or anything else some one might add) consider dedicating that supply to your VHF and look for another supply for your HF.

Clint - W5CPT -

Thanks Clint... the noise is not coming though the antenna. I only get the noise when the 718 is getting it power from the SS-30M and its the same noise if its the only thing connected to the power supply or the Kenwood is also connected. When the 718 is running off battery but the power supply is on and powering the Kenwood there is no noise.

I guess I will try coiling up the wire different and adding snap on ferrites to see if that helps.

Thanks...
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K0YQ
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Posts: 509




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« Reply #3 on: April 25, 2013, 02:40:00 PM »

Hi Jeff,
If you read some of the reviews here for the SS-30M some users have had their noise issues solved by snipping the wires that light the meters.  That is assuming yours is illuminated and you're willing to live without the lighted meters.  I've used a SS30 (no meters) for years.  When I first got it I had terrible birdies/noise, which was all solved for me simply by tightening everything up inside the unit.  It's been quiet and dependable on my K2 since.  Good luck!
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K7GDE
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« Reply #4 on: April 25, 2013, 02:51:55 PM »

Hi Jeff,
If you read some of the reviews here for the SS-30M some users have had their noise issues solved by snipping the wires that light the meters.  That is assuming yours is illuminated and you're willing to live without the lighted meters.  I've used a SS30 (no meters) for years.  When I first got it I had terrible birdies/noise, which was all solved for me simply by tightening everything up inside the unit.  It's been quiet and dependable on my K2 since.  Good luck!

Thanks for the idea... the meters don't seem to light up but I will check again when its darker. I still need to pick up some more ferrite snap ons also to see if that fixes it, but I would rather have no noise then meter lights if it does light.
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K0YQ
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Posts: 509




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« Reply #5 on: April 25, 2013, 04:57:50 PM »

I'd really start by just opening up the supply and tightening all the screws holding the boards.  That was recommended to me and it worked perfectly after everything was snug.  Be safe of course...
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K7GDE
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« Reply #6 on: April 25, 2013, 05:05:57 PM »

I'd really start by just opening up the supply and tightening all the screws holding the boards.  That was recommended to me and it worked perfectly after everything was snug.  Be safe of course...

Thanks that is easy enough to try!
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K1CJS
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Posts: 6055




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« Reply #7 on: April 26, 2013, 04:59:21 AM »

Besides tightening the screws, visually and mechanically check the connections that you can see.  Sometimes a cold solder joint can be causing trouble like you have.   It's doubtful on an Antron, but if someone opened it up before to check or repair it, it's possible.
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K7GDE
Member

Posts: 5




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« Reply #8 on: April 29, 2013, 12:29:12 AM »

I tightened up all the screws (They seemed fine) and visually everything looked good. I added snap on ferrite to the wiring and helped to cut the noise. That does not fix the cause but it at least puts a bandaid on it. There is still a little noise but its only about 1/2 of an S unit more noise now then when run of batteries. I can live with that, especially since its only on 40m and none of the other bands. 
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