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eHam Forums => Station Building => Topic started by: AD9DX on July 07, 2013, 11:36:32 AM



Title: Switching power supplies
Post by: AD9DX on July 07, 2013, 11:36:32 AM
I have a linear Astron power supply that I use in my shack and am quite pleased with it. However our local club does a few contests a year and when I operate, I like to bring my rig.  That being said, disconnecting my 35 amp linear supply and carting that thing around is a complete pain in the hmmm back.  So I was looking into getting a switcher to use for those applications.

I don't think I need to have anything too special I run a K3 and wouldn't be taking any shack accessories with me. But I worry about noise from said switching supply. Anyone have any good suggestions for a supply that I can use and that costs under $200.


Title: RE: Switching power supplies
Post by: W8JX on July 07, 2013, 11:54:09 AM
I have used a Aston SS 30 for several years and have no complaints. Very light weight too. Switching supplies are not effected much by supply voltage variations either.


Title: RE: Switching power supplies
Post by: AD9DX on July 07, 2013, 12:06:54 PM
Cool. I'll keep my eye out at the Indianapolis hamfest next weekend.


Title: RE: Switching power supplies
Post by: AC4RD on July 07, 2013, 12:17:50 PM
I wanted a small switching supply recently, to avoid lugging my thousand-pound linear supply around.  I bought a QJE 30A supply from one of the big vendors just because it was on sale and it little.   It has a "noise offset" control on the front, but I've never needed it, and I've never noticed any significant noise from it.  I'm entirely satisfied with it--FWIW. YMMV.


Title: RE: Switching power supplies
Post by: K1CJS on July 07, 2013, 04:12:46 PM
Just my .02, but Samlex supplies have a good reputation too.  Their SEC 1223 would be the one you may want to look at.


Title: RE: Switching power supplies
Post by: KE7TMA on July 07, 2013, 08:57:55 PM
Just my .02, but Samlex supplies have a good reputation too.  Their SEC 1223 would be the one you may want to look at.

The SEC 1223 has numerous problems with noise.  It generates a bunch of noise all over HF.  There are mods on the internet that deal with this however.  I own one and it was reasonably priced, and it has been with me since I was licensed.

I now only use it to charge my batteries so the noise problem is not an issue for me, but it is something to consider.


Title: RE: Switching power supplies
Post by: K2OWK on July 07, 2013, 11:45:13 PM
I use a Mega-Watt 30 amp supply on my Yaesu FT-450AT with no noise problems. This supply is inexpensive and in the years I have used it I have had no problems. I also have an Amazon.com power supply I picked up reel cheep (less then $20.00). I fully tested it, and I am using it on my Yaesu FT-4700RH. It is also a 30 amp supply that looks like the Mega-Watt, but comes with no hook up instructions, The hook up is very easy. If you want to save money and do not mind fully testing the cheep supply very thoroughly. Either one of these would work. I get no hash or noise from either one. The Mega-Watt is on HF/6, the unnamed cheapo is on a 2/70 radio.

73s

K2OWK


Title: RE: Switching power supplies
Post by: SWMAN on July 08, 2013, 03:51:04 AM
 I use the Astron SS-30M the one with the meters. Been good and reliable for me for 14 years now with no noise at all. It sells for about 165 bucks. I highly recomend it. Good luck and 73. Jim W5JJG


Title: RE: Switching power supplies
Post by: K1CJS on July 08, 2013, 04:33:59 AM
...The SEC 1223 has numerous problems with noise.  It generates a bunch of noise all over HF.  There are mods on the internet that deal with this however.  I own one and it was reasonably priced, and it has been with me since I was licensed....

Any switching supply has that possible problem--the possibility of noise generation.  It's the nature of the beast.  I have a Radio Shack switcher, the 25 amp model--which is also made by Samlex.  I heard about the noise problems with those and was wary--until I plugged it in and saw how quiet it was, fan included.  A buddy of mine got one--and his WAS noisy, and some of the noise was from the fan. 

The only problem I had with mine was some intermittant static after the supply had been in use a few weeks--which I traced down to bad solder joints.  After those were resoldered--quiet once again.  Maybe MFJ got into the act somehow!  73. 


Title: RE: Switching power supplies
Post by: W8JX on July 08, 2013, 09:59:00 AM
...The SEC 1223 has numerous problems with noise.  It generates a bunch of noise all over HF.  There are mods on the internet that deal with this however.  I own one and it was reasonably priced, and it has been with me since I was licensed....

Any switching supply has that possible problem--the possibility of noise generation.  It's the nature of the beast.  I have a Radio Shack switcher, the 25 amp model--which is also made by Samlex.  I heard about the noise problems with those and was wary--until I plugged it in and saw how quiet it was, fan included.  A buddy of mine got one--and his WAS noisy, and some of the noise was from the fan. 

The only problem I had with mine was some intermittant static after the supply had been in use a few weeks--which I traced down to bad solder joints.  After those were resoldered--quiet once again.  Maybe MFJ got into the act somehow!  73. 

This problem is overstated because modern devices from TV to radios to phone chargers all using switches supplies. With a good design there is no problem.


Title: RE: Switching power supplies
Post by: N0YXB on July 08, 2013, 10:36:16 AM
I have had good luck with the Alinco DM-330MV.


Title: RE: Switching power supplies
Post by: NZ0T on July 10, 2013, 11:04:58 AM
I've had an MFJ 4125 for years.  Small size, no RFI that I've ever noticed and nary a problem with it.  I've used it in the shack, at FD and at our lake cabin.  The only negative is a loud fan and mods exist to fix that.  Of course there is always the MFJ quality control factor.  I got one that was well made.


Title: RE: Switching power supplies
Post by: KE7TMA on July 10, 2013, 03:45:19 PM
...The SEC 1223 has numerous problems with noise.  It generates a bunch of noise all over HF.  There are mods on the internet that deal with this however.  I own one and it was reasonably priced, and it has been with me since I was licensed....

Any switching supply has that possible problem--the possibility of noise generation.  It's the nature of the beast.  I have a Radio Shack switcher, the 25 amp model--which is also made by Samlex.  I heard about the noise problems with those and was wary--until I plugged it in and saw how quiet it was, fan included.  A buddy of mine got one--and his WAS noisy, and some of the noise was from the fan. 

The only problem I had with mine was some intermittant static after the supply had been in use a few weeks--which I traced down to bad solder joints.  After those were resoldered--quiet once again.  Maybe MFJ got into the act somehow!  73. 

This problem is overstated because modern devices from TV to radios to phone chargers all using switches supplies. With a good design there is no problem.

It's only overstated if you don't have a noisy switching power supply like the SEC-1223.


Title: RE: Switching power supplies
Post by: K1CJS on July 10, 2013, 07:18:38 PM
This problem is overstated because modern devices from TV to radios to phone chargers all using switches supplies. With a good design there is no problem.

It's only overstated if you don't have a noisy switching power supply like the SEC-1223.

Not to push the matter, but just because you have one that is noisy doesn't make all of the Samlex supplies bad.  The reviews section here has the score of 4.4 out of 5 for an average.  That's pretty good--for what you claim is a bad, noisy power supply.


Title: RE: Switching power supplies
Post by: AC4RD on July 11, 2013, 04:19:20 AM
Not to push the matter, but just because you have one that is noisy doesn't make all of the Samlex supplies bad.  The reviews section here has the score of 4.4 out of 5 for an average.  That's pretty good ...

I have one of those Radio Shack 25A switching supplies that you mentioned earlier.  A few years ago I needed a PS fast and couldn't wait for mail-order, so I went to the mall and bought that one.  These days it's mostly for backup, secondary use, and back-yard portable operating.  The one I bought is also perfectly decent--no detectable noise.  No complaints here!


Title: RE: Switching power supplies
Post by: NZ0T on July 11, 2013, 04:31:10 AM
This problem is overstated because modern devices from TV to radios to phone chargers all using switches supplies. With a good design there is no problem.

It's only overstated if you don't have a noisy switching power supply like the SEC-1223.

Not to push the matter, but just because you have one that is noisy doesn't make all of the Samlex supplies bad.  The reviews section here has the score of 4.4 out of 5 for an average.  That's pretty good--for what you claim is a bad, noisy power supply.

I bought a 35 amp Jetstream switcher with battery backup that had terrible S9+ birdies up and down all the HF bands.  It was even worse when the backup charging line was hooked up to my batteries.  I ended up sending it back   Yet the reviews for this particular PS are generally positive. Guess I just got a bad one.


Title: RE: Switching power supplies
Post by: AA4PB on July 11, 2013, 08:23:20 AM
Switching power supply noise into the receiver is dependent on the distance between the antenna and the power supply, whether or not there are any common mode currents on the antenna feed line, and the type of antenna, in addition to the actual noise being generated by the supply. For that reason one person may report no noise from a particular make/model of power supply while another reports bad noise.


Title: RE: Switching power supplies
Post by: KE7TMA on July 11, 2013, 04:53:32 PM
This problem is overstated because modern devices from TV to radios to phone chargers all using switches supplies. With a good design there is no problem.

It's only overstated if you don't have a noisy switching power supply like the SEC-1223.

Not to push the matter, but just because you have one that is noisy doesn't make all of the Samlex supplies bad.  The reviews section here has the score of 4.4 out of 5 for an average.  That's pretty good--for what you claim is a bad, noisy power supply.

There have been quite a few mods made available for the Samlex SEC-1223 on the internet over the past few years.  I haven't heard of anybody exactly saying it's a bad PSU, but some people have identified and cured RFI caused by design choices (flaws or cost cutting) in the unit.

I have had mine for years now and it has always been reliable, however like others I have noted a drop in voltage when it is under load.