[Elecraft] (OT) - Unplanned Discovery

Sun Nov 19 20:39:05 EST 2017

Rich,
     You just discovered the problem with switching power supplies. I'm 
unaware of any computer power supply that isn't a switcher, but for most 
12 volt needs an analog supply should fix the problem. The only downside 
that I can see is weight; analog supplies can be a bunch heavier, but 
they are RF quiet.

     There some quiet switchers out there. You just need to do some 
research to discover those. One that is quiet is the Tentec. It is 
actually an Astron that Tentec did some work on. I think the one 
Elecraft sells is quiet. Bit, you really need to investigate before 
buying a switcher.

73,
Barry
K3NDM

------ Original Message ------
From: "rich hurd WC3T" <rich at wc3t.us>
To: "stan levandowski" <sjl219 at optonline.net>
Cc: Elecraft at mailman.qth.net
Sent: 11/19/2017 7:31:48 PM
Subject: Re: [Elecraft] (OT) - Unplanned Discovery

>Wow.
>
>Going to try that.   Thanks for this great post.
>
>On Sun, Nov 19, 2017 at 19:23 stan levandowski <sjl219 at optonline.net> 
>wrote:
>
>>Most people on this Reflector are well educated and intelligent.
>>Apparently, I'm the exception because this one got by me.  I'm only
>>owning up to this in the hope that it might help someone else on the
>>Reflector.
>>
>>For the last couple of years I've been bothered by a high background
>>noise level.   It happened on my K1, K2, K3, KX2 and KX3.   I 
>>attributed
>>this to the fact that my antenna has been in my attic for the last
>>fifteen years and propagation hasn't been good lately.
>>
>>
>>I just got official permission from the HOA to install an end fed wire
>>outside.  I was thrilled.  I put it up.  The darn thing wasn't any
>>better than the attic doublet.  Noisy as heck!  What a letdown!
>>
>>
>>So I'm laying in bed last night reflecting on how my little KX1 was 
>>the
>>only Elecraft radio that never had noise problems and seemed to have a
>>receiver quieter than my K3.
>>
>>
>>Whoa!  The KX1 always ran on batteries...could it be?????
>>
>>
>>I just took delivery on a brand new Kx33 Low RFI power supply a couple
>>days ago. It was advertised in the last QST.   Previous to that, I've
>>been using a Samlex 1235M.  For the heck of it,  I connected my K2 to 
>>an
>>SLA battery and the noise was still there.  But when I disconnected 
>>the
>>Kx33 power supply from the wall, the noise level dropped dramatically.
>>Then I switched to the Samlex and the noise came back.  Back on the
>>battery, the noise dropped again as long as the power supplies were
>>unplugged and dead.
>>
>>
>>I have a laptop next to the computer.  When I pulled the plug on the
>>laptop supply, the rest of the noise went away.  I was down to S0/S1 
>>and
>>CW signals were popping out all over the band again.  Running the
>>computer on its internal battery did NOT contribute any noise.  It was
>>the computer power supply.
>>
>>
>>Now that I am totally on batteries, I also appear to be immune from 
>>both
>>the gas furnace and the dishwasher motor both of which caused me
>>problems when using the AC supplies.  YES, I HAD CHOKES ON ALL 
>>SUPPLIES,
>>CABLES, WIRE.
>>
>>
>>I've been on the air all day with my new outside antenna, on battery
>>power,  making contacts near and far and I feel like I've hit the
>>jackpot.  Since I'm totally QRP and CW, being limited to batteries is
>>not an issue.
>>
>>
>>If you're going to check your own supplies out, remember they've got 
>>to
>>be OFF/UNPLUGGED from the wall. Just disconnecting them from the
>>radio/computer isn't enough.  It's RF.
>>
>>
>>73, Stan WB2LQF
>>
>>
>>
>>
>>
>>
>>1
>>
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>
>--
>---
>72,
>Rich Hurd / WC3T / DMR: 3142737
>PA Army MARS, Northampton County RACES, EPA-ARRL Public Information 
>Officer
>for Scouting
>Latitude: 40.761621 Longitude: -75.288988  (40°45.68' N 75°17.33' W) 
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