[Lowfer] Whatever happened to our old Lowfer band?

[C. Turner]

The big noises that I hear on the LowFER frequencies are switchers and 
compact fluorescent lights - mostly the latter.  It would seem that most 
common switchers run at 30-40 kHz while CFLs seem to be around 55-65 
kHz, but the harmonics aren't well suppressed.  I suspect the 'loosed 
roar of hell at night is everyone switching on their CFL's.  (Plasma 
TV's are even worse!)

At just the 2nd or 3rd harmonic I've observed that some CFLs actually 
produce a surprisingly pure note - although it is usually modulated with 
AC - with the frequency drifting around based on how long the lamp has 
been on and with slight variations in the line voltage.  I don't know 
what sort of signals Plasma TV's produce when you are fairly close to 
the fundamental frequency, but I do know that they radiate a pretty 
massive E-field.

My observation is that switchers used in monitors/computers are 
reasonably-well EMI filtered and cause low-moderate QRM but that that's 
not at all the case for CFL's which appear to have little more than a 
small amount of inductance in series with the line (if anything at all) 
plus a bypass cap across the line.

Fortunately, pretty much all of the racket that I hear on LF is within 
my own house as it seems as the low frequencies don't propagate well - 
at least with underground power feeds.  To quash VLF/LF QRM from the 
power supplies I've had to do the usual list of things like add 
capacitance, chokes on input and output lines, isolation transformers on 
audio and put USB, audio and DC lines on flyback transformer cores.

With all of these - plus the judicious use of light switches and the 
strategic placement of a good 'ole incandescent lamp at the operating 
position in the shack has reduced the grunge to a tolerable level.

A friend and I were talking about the fact that "traditional" amateur 
radio TVI is going away - but the TVs and other appliances are striking 
back with QRM.

Clint
KA7OEI/CT


Lee wrote:
> I was playing around with some receivers in the garage last weekend and also heard some very hot local QRM.
> The garage is my only sorta quiet RF spot without putting an E-Probe 33ft in the air. Specifically I heard an
> S5 carrier at 195khz. My area is in the process if getting "smart power meters". My guess is that 195khz
> carrier was from my local Power CO.
> -----Original Message-----
>    
>> From: Bill de Carle<ve2iq at magma.ca>
>> Sent: Feb 23, 2011 5:43 AM
>> To: "Discussion of the Lowfer (US, European,&amp;
>> 	UK) and MedFer bands"<lowfer at mailman.qth.net>
>> Subject: [Lowfer] Whatever happened to our old Lowfer band?
>>
>> It must be at least a year now since I've done any listening on the
>> 160-190 Khz Lowfer band.  Yesterday I set up two loops to favor a
>> NE-SW line and tuned a preamp for 188.83 Khz, which produced good
>> copy of EAR's QRSS30 beacon for most of the day.  When nightfall came
>> however, all hell broke loose!
>>
>> First thing I noticed: a high power pulsed signal appeared spreading
>> RF all over the place.  This was not accidental radiation, it was a
>> deliberate transmission right in the band.  Shortly afterwards I
>> observed someone sending sequential tones - very strong signal
>> appearing out of nowhere.  Guess it could have been WSPR or fast
>> Jason, something like that, but definitely much too loud for 1 watt
>> DC input to the final and a 50-foot antenna.  All the while having to
>> contend with the broadcast station on 189 Khz (Iceland?) obliterating
>> the top of the band with its music.  My S-meter climbed up, up until
>> the AGC suppressed EAR's signal below visibility.  Admittedly I had
>> too much gain before the Rx for those conditions but I didn't feel
>> like going out in the dark with a flashlight to change the
>> configuration at the antenna so I gave up.
>>
>> I don't remember things being that bad in years past.  In particular,
>> those pulsed and tone transmissions don't seem to be coming from any
>> amateur station - they're way too strong and obviously designed to
>> punch a message through on a crowded channel.  Like when 11 meters
>> degenerated into a shouting match where the game was to see who could
>> run the most power without getting into trouble.  I've seen
>> similar  pulsed and tone signals on the hifer bands: 13.553-13.567
>> Mhz and especially around 6.777 Mhz in the Canadian unlicensed
>> band.  I'm wondering if some company is selling uncertified
>> transmitters to the general public or what else might have
>> happened.  There was no significant static (QRN) last evening, it was all QRM.
>>
>> My rant for the day.
>>
>> Bill VE2IQ
>>
>> ______
>