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Author Topic: power supply recommendation?  (Read 3200 times)
W7EJT
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Posts: 135




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« on: November 06, 2012, 11:12:19 AM »

Kenwood TS-450s

I am using an old 13.8v / 25A switching power supply. I believe this is the culprit to my receiver "hash" noise level. (Just bought the rig and have never used this power supply ("Radius Power" - not a brand name). 13.5 volts is measured at the PS output terminals. If I had a scope - maybe I could check the ripple.

Anyhow - I have decided to get a good power supply. Reviews on MFJ aren't too good. That only leaves (besides Kenwood) just a few others - Pyramid, Astron, etc.

I'm looking for a Quiet power supply. Even my current switching power supply has a noisy fan...

Any recommendations?

thx
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AA4PB
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« Reply #1 on: November 06, 2012, 11:25:47 AM »

Unless you really require the smaller size and weight of a switching supply, I'd recommend an Astron linear power supply. Linear supplies have no switching circuits to generate RF hash.

Virtually all switching supplies generate noise - the only difference is in how much. The distance between the supply and the antenna as well as common mode (poor balance) on the antenna feed line can also play into how much RFI level you can tolerate from the power supply.

Also, you probably want to test to ensure that the RFI hash you are hearing is really comming from the power supply before investing in the new supply. You can do this by powering your radio from a battery temporarily. Even a small gell cell can power the receiver for a few minutes - long enough to run a test.
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K8AXW
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« Reply #2 on: November 06, 2012, 12:04:15 PM »

4PB laid it out, A,B,C.  Other than seconding his recommendation of the Astron linear supply, I can't add anything else.

Oh..... many hams give Astron a thumbs down but I can assure you that most ham stations that require a 13.8VDC power supply uses an Astron!  They good a good job and if they do crap out, they're easy to repair, unlike the switchers.
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WX7G
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« Reply #3 on: November 06, 2012, 12:10:29 PM »

The Astron 20A is a linear supply and so is inherently RFI quiet.
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W7EJT
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« Reply #4 on: November 06, 2012, 12:24:25 PM »

Thanks for the tips, guys! I'll try the battery trick - and now looking for an Astron PS!!

73
Alan
Myrtle Beach
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VE7DQ
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« Reply #5 on: November 06, 2012, 01:16:42 PM »

I purchased a Powerwerx SS-30DV switcher just to see how noisy it was; It isn't!  Very quiet. 

If I were looking at a linear supply to remove all doubt, I'd look at an Astron 35 Amp supply.  A 20 Amp Astron is usable, but has no overhead.

73
Tom
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WA8MEA
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« Reply #6 on: November 06, 2012, 02:46:57 PM »

Oh, boy Alan....

You are gonna get about as many opinions with this question....as hair follicles on a butt cheek.

For some reason, I am one of those who believes that certain companies/products are just snake-bit with some folks.  It's like Ford, GM and Chrysler.  Some swear by them; while others swear at them.

I, too, gave up on the switching supplies because of the RF hash.  So that meant regulated supplies with heavy transformers and BIG shipping charges.

My first issues started with Astron.  I bought TWO 25 amp supplies that buzzed more than my electric chain saw!  I then upgraded(?) to a marine battery and smart(?) charger until the smart(?) charger went haywire and started a fire in the shack.  So back to power supplies.

I began with Tripp-Lite...on the "Lite" side.  A four amp for QRP stuff and a 10 amp for VHF stuff.  They have worked perfectly for more than a decade.  I then opted for an MFJ regulated for the HF rigs.  Fan was noisier than my Lesko box fan in the summertime! 

I then went to Amazon and found a new Pyramid PS-36KX dirt cheap and free shipping. (Which is great for as much as this regulated variable supply weighs.)  That supply has been working FB for me for several years, IN SPITE of the fact that the on/off switch broke a few months ago. (I simply wired it permanently on and put an on/off switch in line with the AC power cord....) 

So, in my opinion, which is worth a plug nickel to many....a Tripp-Lite or a Pyramid should do you well.

73, Bill
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AC5UP
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« Reply #7 on: November 06, 2012, 04:28:59 PM »

...until the smart(?) charger went haywire and started a fire in the shack.

Yeah, but aside from that it wasn't a bad idea.

I have no idea if this is still a cost effective option, but 15 years ago it was not uncommon to find good deals on used & surplus Lambda, Acopian, PowerOne, commercial linear supplies. The market was moving to switchers and the linear jobbies were becoming a tougher sell. Didn't bother me... Not something I move very often so the weight and size wasn't an issue. I stocked up on a pair of 19 amp Lambda cinder blocks of the 15 volt persuasion and tweaked them to 14 volts straight up. Never regretted the plan as the 19 amp rating on a Lambda is like " 25 " or more on an Astron. I have nothing in the shack that needs more and have never pushed the brick into warmer-than-I'd-like territory or seen one fold back.

So............. Most folks have good luck with an Astron, same as others have with a switcher, but you will hear competing opinions. If it were me I'd look for a gently used commercial quality supply that was built for reliability rather than price.
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W7EJT
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« Reply #8 on: November 06, 2012, 05:48:12 PM »

Reporting results:

I measured the S meter level at 7.15 MHhz (standard SSB settings on my TS-450s) USING my "Radius" (brand) power supply. Also, I just used a 10' piece of wire for an antenna. S meter was mostly hash and at S-9. Can hardly receive anything but very strong signals - thru the hash.

Then I unhooked everything and took the receiver out to the car and hooked up directly to the car battery. Using the same settings for SSB and the same antenna - S-Meter was at 2 - and hash was minimal! Received lots of signals in the garage.

So, the bottom line is that the "Radius" switching power supply is guilty of providing lots of hash.

I did some internet research and found that this 13.8V / 25A power supply is used to power bath tub water pumps for a jetted tub.

I picked this PS up for $10 or so, years ago and never used it (it's new). Oh, it's not made in China.

Apparently some switchers and different than others.

I have a Astron 35 amp Linear on its way...

Thanks for all the inputs. :-)

Alan
Myrtle Beach
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K8AXW
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« Reply #9 on: November 06, 2012, 08:48:19 PM »

Al:  I don't think you'll be sorry for buying the Astron 35A.  I've heard others talk about "buzzing" and other "problems" but I've never had a problem with mine.

I've worked on several that had a componet failure, which can happen to anything we own.  The great thing about the Astrons is they are easy to work on.

The Lambda are the "Cadillac" of the power supplies.  I've never seen one fail in the 16 years we used them for instrument backup on our power plant boilers.

The Pyramid uses the same regulator control board as the Astrons and basically the same overall design.

 
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K4RVN
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« Reply #10 on: November 07, 2012, 08:03:31 PM »

Good choice there Allan in M.B. I have two RS 35 Astrons and both are very quiet and very dependable. One is 24 years old.
No meters on mine. I support your choice for a 35 as you won't be operating near the max output on that one. I stay at
Ocean Lakes on the south 17 when in MB.

Frank
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K1CJS
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« Reply #11 on: November 08, 2012, 03:50:22 AM »

You said it yourself in your first post--you got an old switcher.  Most of the newer switching power supplies are as quiet as they can be.  No noise or hash.  The older ones, however.....

Let's put it this way--put it back up for sale and let someone else deal with it!
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K5LXP
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« Reply #12 on: November 08, 2012, 06:04:55 AM »

Then I unhooked everything and took the receiver out to the car and hooked up directly to the car battery.

By moving the radio and antenna out into the garage you may have also moved farther away from a potential source of noise other than the power supply you wanted to substitute.  The right way to test this is to change the power source without changing anything else.

Also, with just a local piece of wire as an antenna, your chances of ingress from just about any local source is very high.  That's not saying the power supply isn't a contributor but with the door wide open to your radio like that, anything on the AC lines or other device spraying EMI in the vicinity will come right through. 

By keeping the receiver and antenna configuration the same and only replacing the switcher with a different power source you can more conclusively prove what the source of noise is.


Mark K5LXP
Albuquerque, NM
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AA4PB
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« Reply #13 on: November 08, 2012, 07:00:09 AM »

"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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W7EJT
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« Reply #14 on: November 08, 2012, 08:52:35 AM »

OK, Great inputs!!! I did have the short "test antenna" very near the switching power supply. Now that I have my new antenna constructed (yesterday) - I will see if the old switcher still has the RFI... Will report back soon...

Thanks, again!

Alan
Myrtle Beach
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