[SMCARA] HAM Detectives

Wed Jul 7 09:11:51 EDT 2010

Another data point in the great Linear versus Switch Mode power supply
war!  Anything with square waves will be a noise generator! Lack of
filtering and bypassing is the culprit, and that we know, is bottom line
driven!

CFLs, cell phone plugin chargers, laptop computer power warts, dimmers,
and just about anything with a microproc in it are noise sources.

QST did a review a few years ago of switching power supplies, complete
with info on how "quiet", RFI-wise they are.  My little Semlex 23 amp
Rat Shack special is silent, but a big dollar Icom power supply for the
IC-746 is a real jammer!  Go figure!

73 Tom/W4OKW 

Tom Clarke
Wyle, Inc  Aeronautics
P3 Product Lead, PEO(A)
USN/USMC National Airworthiness Office
Naval Air Systems Command, AIR-4.0P
(301) 995-3793/DSN 995-3793
Fax: (301) 342-3776
Cell (301) 904-2053
frederic.clarke at navy.mil

"Do not let spacious plans for a new world divert your energies from
saving what is left of the old."

Winston Churchill

-----Original Message-----
From: smcara-bounces at mailman.qth.net
[mailto:smcara-bounces at mailman.qth.net] On Behalf Of KG3BOZ
Sent: Tuesday, July 06, 2010 8:44 PM
To: 'SMCARA Reflector (E-mail)'
Subject: Re: [SMCARA] HAM Detectives

First, I would like to thank all of you who helped me in this matter,
both big and small.

Thank you to KC0WKX (Ed Pratt) for offering a loan of his FT-817 and
tuner
For troubleshooting.

Thank you to K3KLC (Sam) for loaning me his Radio Shack DX 400 shortwave
Receiver and his personal expertise in troubleshooting the problem.
Sam actually delivered the radio to my QTH.

Thank you to WB3CZI (Joe Phelps) for his in depth troubleshooting advice

Via e-mail.

Thank you to KB3FWW (Ray) for loaning me his Sony Shortwave Receiver. 
Ray actually delivered the radio to my QTH.

A big thank you to W3BNY (Rene) for his troubleshooting advice, loan of
his 
Dummy load and a short length of coax replacement. Rene drove to my
house,
brought his equipment and helped me troubleshoot for at least two hours.

Last, (but not least) thank you to everyone who e-mailed offering advice
and lessons learned for RFI. There were a lot of you who did this. 

What's that you say?  What was the source of the RFI?  Not so fast my
little grasshopper.....

Two weeks ago my outdoor HVAC unit failed (I think due to a lightning
Storm). I had the HVAC replaced (an expensive event, by the way).

Shortly thereafter, I started to notice high levels of static from six 
Meters all the way to 80 meters.  It was so strong, it wiped out the
entire band, rendering them useless for the all important digital
modes.  Frustrating to say the least.  

The obvious culprit was the new HVAC. After investigation I noticed
the noise may be present if the AC unit was blowing or not - it made
no difference. So then I took the plunge and shut the AC Unit off at
the switch box. That also made no difference.

Sam brought his battery powered SW receiver over to my QTH.  It did
indeed
pick up the same noise.  Then we discovered my Kenwood TS 2000 picked up
the noise even with ALL ANTENNAS disconnected!  

My next step was to drive down the local roads with a radio tuned to 28
MHz
in AM mode to see if I could pick up the interference.  I could not
locate
any source of interference that way.  I also walked around the
neighborhood
listening for interference.  I didn't find any QRM, (but I did discover
some power boxes that are made in my XYL's home town in California).

Then Rene came to visit me with his battery powered amateur rig. If you
went to the SMCARA field day this year, you know what rig I am referring
to.
(If not why didn't you go? But I digress).  Long story short, with
Rene's
Rig connected to the battery and everything in my shack shut off, there
was
no interference.  Rene said something to the effect of, 'it is a power
issue.  Either your house power is causing it, or something in your
Shack is causing it'.  We disconnected the obvious things one at a time.
The source of the problem turned out to be....    Drum Roll....

My Alinco DM 330MV power supply.  After switching it out with my Astron
35A power supply, I have not experienced the problem for two days now.

Thanks again to all who helped.  The spirit of amateur radio is still
Alive and well, at least here in 'The County'.

Now I can get back to working DX and enthralling all of you with my
exploits.  Which reminds me:  Did I tell you I worked ZL1BYZ on 17
Meters?  I just received the QSL card in the mail.

73 DE KG3BOZ "Boz"

-----Original Message-----
From: smcara-bounces at mailman.qth.net
[mailto:smcara-bounces at mailman.qth.net]
On Behalf Of KG3BOZ
Sent: Saturday, July 03, 2010 9:49 AM
To: SMCARA Reflector (E-mail)
Subject: [SMCARA] HAM Detectives

Hams with experience finding and eliminating QRM, lend me your 
eyes and ears:

I need your help.  For about a week now, I have been experiencing very
heavy QRM across the -entire- HF Spectrum.  I can even hear it on six 
meters (weaker) through 80 meters. It's so heavy at times, the signal 
meter on my TS 2000 is PEGGED.  It's not ALWAYS there, but it is there
more often than not.  The end result is that it effectively wipes out
my receive capability.  Two meters seems unaffected.

After speaking with KJ4FZT (Grant) my thought on how to find it was 
to use an HF battery operated station, we could hook it up, and then
kill the power mains to the house.  If the interference goes away, 
we will know it is inside my house and troubleshoot accordingly.  
If it doesn't go away, it's outside the house and then make plans
to DX it.

I do not have a battery operated station or experience in finding
interference.  If you have one or both of the above, please let me
know if you can assist.

DE KG3BOZ

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