QSO on 1980...how it happened

[flintstone mop]

Hello Radio Friends
I was curious, while monitoring 1880 last night, to look for a noise problem that only seems to muddy up my noise floor at night. A 10 over 9 buzz every 40khz on various bands, 160 being the worst. This signal had a large sig reading at 1980, for some reason. So, I walks around the house with my trusty Radio Shack DX390 and "sniffed" around the house passing the antenna near the LCD TV and the sat box and cable box. Nothing there. I went into the kitchen and the sig meter was pegged as I got closer to the under cabinet lighting. I had changed this system from 110vac halogens which made the cabinets smell like they were burning to a 12 halogen bulb. I guess I have been bitten by the 12 vdc switching supply that powers the lamps.
 
So, that's off now when I want to operate. Can someone direct me to a link on this forum that addresses the cure for teh RFI from these DAM## switching supplies!!!

Clearing the airwaves from the buzz gave me a noise floor of S-5 and a pleasent QSO with Howard, W3HM and almost Alan KB9DRZ in Wi. Alan dropped out trying to get an AL-80 on the air. His 25 watts wasn't enough for the usual 160M noise. When the lower part of 160 is busy come on up to 1980 or so. This happened 10:30PM Eastern time USA
Fred

[WA1GFZ]

build a linear power supply. You would need a shielded box and filter the leads coming and going to keep the switcher.

[WD8BIL]

Franks right..... for the most part.
Small switches have very little radiated emissons. So at the distance you're talking the problem is almost entirely conducted emissions on the ac mains.

A nice ac line filter would help make it LESS irritating but a simple lineyar supply will be tha cats as....... PJs 

[k4kyv]

I had a loud buzz yesterday when I tried to listen on the AMBC band using my R-1000 and a metal shelf for antenna.  No problem with any of the outdoor antennas. Finally found the source.  It was my space heater that uses quartz radiant tubes.  It has two positions, high and low.  No buzz in high power position, but loud buzz in lower power position.  Must be one of those solid state dimmers to run it at reduced power.

If this gets to be too much of a problem, I'll just run the thing in high power position and turn the voltage down with one of the the 2 kw variacs I have collecting dust in my junk pile.

[Vortex Joe - N3IBX]

Fred,
      Whilst cruising around 1980KC, you may want to listen in for a group of 9 and 0 Landers who frequent on 1985KC. Nice group of guys on that frequency, but sometimes they're just a little too distant to have a comfortable QSO with at a lower power level here on the East Coast, unless conditions are at a premium. Every so often I swish the VFO up to that frequency just to say hello.

Incidentally, I haven't had the pleasure of working you in quite sometime, and hope to catch you on 1885KC. I was tuning around 160M and 75M tonight, but both bands were full of loud cratic stashes!

FYI: a stock unmodified ART-13 will hit 1985KC w/o any further modifications to the VFO, but will not go any lower.

Best Regards,
                  Joe Cro N3IBX

[W1RKW]

Fred,
I had a similar problem with my DSL modem which had a compact wallwart SMPS.   It wreaked havoc on the lower HF bands.  I put it into a box and grounded the box.  No noise anymore.

[Tom WA3KLR]

I wonder if the halogen bulb could just be run from a 12 V filament transformer?  Unless they are doing a needed soft start, the only other reason for the switching supply is to automatically handle universal line voltages 85 - 264 Volts a.c.

See you on 160 AM Fred.

[Vortex Joe - N3IBX]

I wonder if the halogen bulb could just be run from a 12 V filament transformer? 

Tom,
      Bring over a 12V halogen bulb (auto or otherwise) and we'll find out!
      Best Regards,
                        Joe N3IBX