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Author Topic: Samlex 1223 mod  (Read 2173 times)
K6RQR
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Posts: 203




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« on: September 05, 2012, 07:30:04 PM »

Hello All -
 I am considering getting a Samlex 1223 switching supply to power a 100 watt transceiver. I read a review here on eham that mentions adding caps on the output to reduce hash. I know that not everyone experiences hash using one of these units but I was wondering if anyone has added caps to the output to deal with hash or what someone would recommend for the caps to be used. The reviewer I'm mentioning does not have an email address so I can't contact him. Any assistance would be appreciated.

Bruce  K6RQR

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VA7CPC
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Posts: 2388




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« Reply #1 on: September 05, 2012, 08:20:31 PM »

FWIW --

Get it first, and see if you have hash.   If you don't, there's no need for modification.

I'd be _very, very, very_ careful before modifying a factory-built switching power supply.  Just a little bit of  oscillation (that's not supposed to be there) can be destructive.

            Charles

PS -- One thing you can do _safely_:

. . . Wind each output wire (+ and -) through a ferrite toroid.

That will choke any residual RF coming out through the DC power leads -- and it's safe.

PPS -- I have a Samlex 1223, and it hasn't caused me any trouble.  I hope you have my luck.
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KA4POL
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Posts: 1996




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« Reply #2 on: September 05, 2012, 11:20:03 PM »

I'd check with the dealer weather you can return the supply if not happy.
An interesting writeup is http://www.hardwaresecrets.com/article/Why-99-Percent-of-Power-Supply-Reviews-Are-Wrong/410
So be very cautious with those reviews.
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WA3SKN
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Posts: 5486




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« Reply #3 on: September 06, 2012, 04:32:03 AM »

Before "modding" anything, do you have a problem?
My Samlex switching supply is cleaner than my old linear supply.  Some early switchers did have RF noise issues, but the ones now on the market are Very well filtered... so if you are buying a used one there might be a problem.
If there is a problem, an external filter is easy to add... there is no need to mod the existing unit internally.
73s.

-Mike.
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K1CJS
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Posts: 6034




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« Reply #4 on: September 06, 2012, 04:44:57 AM »

I have the Radio Shack version of the Samlex, and it's as clean as I could want.  I second seeing if there is any problem.  If that Samlex is newer than 5 or 6 years old, I wouldn't worry about the noise at all.
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AG6WT
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Posts: 453




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« Reply #5 on: September 06, 2012, 08:43:16 AM »

Bruce,

I think a better solution is to get a better power supply that doesn't need any modifications. As far as small switching power supplies, the Alinco DM-330MVT is a very good model. It has a little dial that lets you tune the hash off frequency. If you hear the noise, turn the dial and it goes away. At least in theory that's how it works. However, in the QST review, when they attempted to test this feature, they couldn't because they couldn't find any hash to begin with!

I've owned that Alinco for a year as well as 3 Radio Shack branded Samlex 1223's. Two of the RS's where very noisy on 80 and 40 meters, producing a 2kHz "whoosh" that would drift up and down the bands. Torroids and caps had very little benefit. The 3rd RS was quiet, or at least quiet in the ham bands. The Alinco was very quiet every where I tuned from 80-10 meters. Also the Alinco fan is extremely quiet. You really can't hear it unless you put your ear right next to it. As I have switched to a high amp linear in the shack I sold my Alinco. However if I needed another compact PS, that would be my first choice.

Ray KJ6AMF
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KD0REQ
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Posts: 950




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« Reply #6 on: September 06, 2012, 09:53:08 AM »

got a Samlex that has no noise at all... the ft890 is its own GCR and I'm hearing nothing adverse.  but I clamped some ferrite chokes on both 12v leads and the line cord just in case it starts to whistle some day down the road.
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K6RQR
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Posts: 203




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« Reply #7 on: September 07, 2012, 05:58:48 PM »

Thanks to all of you for your responses. Very helpful.

73,
Bruce  K6RQR

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W9MMS
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Posts: 120




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« Reply #8 on: September 08, 2012, 11:00:16 PM »

Phil Salas AD5X has done a review on his Samlex 1223.
Here is his opinion ....

http://www.radiodan.com/pdf/SEC1235M_Review.pdf

Here are a list of his reviews ...

https://www.google.com/search?q=ad5x+reviews&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a


(((73))) Milverton.

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W5DQ
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Posts: 1209


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« Reply #9 on: September 11, 2012, 02:41:40 PM »

I have a Samlex 1223 supply and out of the box, it is quiet as a church mouse. No hash, no trash, clean DC.

I did do a mod that keeps the cooling fan turning a slow speed continously until such time as the thermal switch senses it need to go full on and then it runs full speed for a little bit and automatically slows to about 15% of full speed. Takes 1 wire and resistor. Don't recall the specs off hand but do a Google search and it should be readily available. Other than that it is stock and works great.

Gene W5DQ
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Gene W5DQ
Ridgecrest, CA - DM15dp
www.radioroom.org
AE5JU
Member

Posts: 229




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« Reply #10 on: September 25, 2012, 07:17:56 PM »

I've got two SEC-1223s and a SEC-1235M.  No noise problem with any of the three.

We used to have an Alinco 330 or 340 at the club station.  There was a knob that would shift the switching rate to move noise up or down out of the way.

Paul - AE5JU
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