[Fwd: LF: Power line interference]
Tue, 26 Jan 1999 08:26:20 -0500
Mike Dennison wrote:
> Several recent e-mails have reported on, or speculated on, the
> interference from 240V (or 115V) AC power sources. My
> experience is as follows:
> Generators: I have hired a 240V petrol generator on my last two
> trips to GW. I was astonished to find that this was totally noise
> free. The only noise I experienced (and that was on the first trip
> only) was cured by unplugging the 240V supply to the power
> amplifier (which is permanently powered) during receive periods. I
> will note the manufacturer when I next hire one and will report.
> Overhead power lines: I have done quite a lot of portable receiving
> on both 73 and 136kHz. In most cases, power lines of all types
> have an undeservedly bad reputation and are mostly quiet. In fact,
> on some of my 73kHz receiving tests I preferred to be close to a
> 132kV line as this seemed to pick up the signal and re-radiate it.
> However, I have found some lines to be extremely noisy - including
> the one adjacent to my Welsh holiday home. These are usually
> relatively low voltage, 11kV - 400V, and I assume the noise has
> more to do with a fault than design as most of these are noise free.
> The noise tends to radiate for 50 yards or so, but no more.
> Other things to avoid: Some overhead telephone wires are very
> noisy. Also, as reported some time ago, I have found that some
> main roads have something very nasty underground which badly
> affects LF reception.
> In the main, if you can get a few hundred yards from the nearest
> house the noise level should be very low.
> (PS Sorry for appending my business signature to yesterday's
> message - here's the radio one......)
> Mike, G3XDV (IO91VT)