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Author Topic: power supply recommendation?  (Read 3465 times)
WN2C
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Posts: 479




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« Reply #15 on: November 08, 2012, 09:02:52 AM »

If you must have a switcher, I would go with the Alinco... dm 330. Check the reviews here.
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WB6DGN
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Posts: 619




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« Reply #16 on: November 09, 2012, 12:02:12 AM »

Not to hijack the thread but somewhat related question.  Most dedicated switching power supplies (those designed to be installed with a specific piece of electronics) have a minimum load specification below which the supply will not work correctly (or not at all in some cases).  My question, do the general purpose switchers as recommended here also have a minimum load requirement?  Reason I'm asking is this could be another negative in deciding whether to buy a switching supply or a linear one.
Tom
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W7EJT
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« Reply #17 on: November 09, 2012, 09:23:53 AM »

allrightythen! Hooked up to my new attic antenna (not the 10' piece of wire). SAME result!!! Lots of hash that must be coming from the switcher power supply.

Nothing else in the shack (that I can think of) would cause the hash.

As mentioned before - the receiver works great off the car battery in the garage with a 10' wire antenna

I have an Astron 35M coming next Monday or Tuesday. Will report back, then...






"Apparently some switchers are different than others."

ALL switchers have circuits that generate loads of RFI. The question is: how good of a job did the mfg do of shielding and bypassing leads in order to keep the RFI inside the box?

Another very big variable is how far away your antenna is located from the switching supply. A 10-foot piece of wire lying on the table near the supply is about the worst case. Someone else may use that same supply but have a dipole antenna located 100-feet away and tell you that the supply is perfectly quiet!

Switching supplies don't usually generate a constant level RF hash across the entire band. Usually you find rather wide spots in the bands where hash is present and those spots often move (drift) around, especially as the load changes. One switcher mfg even has a knob on the supply that allows you to change the switching frequency and move the noise spots away from your favorite frequency.

If your noise is across the whole band(s) then there is a good possibility that the noise is coming from some electrical device in the house rather than the switching supply. Don't panic if you hook up the new supply and still have the noise - the new supply is probably not bad too  Cheesy

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K5LXP
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« Reply #18 on: November 09, 2012, 10:22:28 AM »

allrightythen! Hooked up to my new attic antenna (not the 10' piece of wire). SAME result!!!
Lots of hash that must be coming from the switcher power supply.

You're still doing incorrect substitutions.  We know the RFI is coming in the antenna.  You need to substitute the supply without changing anything else.


Quote
I have an Astron 35M coming next Monday or Tuesday.

That'll prove it though.


Mark K5LXP
Albuquerque, NM
« Last Edit: November 09, 2012, 10:29:48 AM by K5LXP » Logged
N7EKU
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Posts: 132




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« Reply #19 on: November 18, 2012, 11:15:56 AM »

allrightythen! Hooked up to my new attic antenna (not the 10' piece of wire). SAME result!!! Lots of hash that must be coming from the switcher power supply.

Nothing else in the shack (that I can think of) would cause the hash.

As mentioned before - the receiver works great off the car battery in the garage with a 10' wire antenna

I have an Astron 35M coming next Monday or Tuesday. Will report back, then...

Are you sure???

Every single wallwart power adapter and laptop power supply in my house generates loads and loads for RFI.  From my exerimenting, it tends to vary a lot with the quality of the supply and the distance from the device.  The distance from my wallwarts to the closest part of my antenna strung on the corner of my house is about 15 feet, so I am perhaps more susceptable than some, but maybe not in a unique situation by any means.

Want to test it?  Put your rig on 80M and not on a station, then go plug/unplug your wall power adapter from the wall socket.  You can also test if it's a certain one by just grabbing the plastic adaptor case with your hand -- then your body will act like a transmitting antenna.

All I can say is I am now in the process of moving my antenna farther away and doing my best to eliminate all the unneeded wall wart power adaptors (in the whole house) I can.  Even so, my neighbors in the townhouse nextdoor have at least one bad device that they occationaly turn on that make a ton of RF noise (at least the are quiet folks in the audible range!)

Some of the really old ones are OK as they are 60Hz transformer-based, but all the ones I have from the last couple decades are switchers.  Of course there's a reason for this change -- they are much more efficient, much lighter, and require less raw material to build.  But there certainly are tradeoffs hihi!

Good luck with your RFI hunting and 73!


Mark - N7EKU

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G4AON
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Posts: 543




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« Reply #20 on: November 19, 2012, 02:58:26 AM »

Glad to see the Astron has a crowbar protection circuit, which is a "must have" in any power supply.

I've had two linear (non switching) power supplies fail, one was powering radio equipment worth about 30 times more than the cost of the power supply and had a crowbar fitted by me that worked by blowing a fuse in the supply, the other was a plug top (wall wart) supply that blew an audio amplifier.

73 Dave

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W7EJT
Member

Posts: 140




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« Reply #21 on: November 19, 2012, 01:00:04 PM »

RESULTS:

Hooked up my new*to me) Astron 35M - BINGO!!! No more profound hash! Apparently Linear PS is the way to go. Thanks for all the tips.

My 25 Amp (noise generating) switcher has already sold on eBay.

Alan
Myrtle Beach
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