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Old October 25th 04, 05:44 AM
Hal Rosser
 
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"Thierry" - wrote in message ...
Hi,

I friend of mine, ham, is handicapped and cannot move without his

wheelchair
He experiments QRM on low bands 160/80/75m induced by the fence installed

by
his neighbor
I don't know what kind of fence it is, and if it is really close to his
house or miles away...

He would like to know if a rotaty loop antenna could remove this QRM ?

I used a Wellbrooks ALA1530 and I am not sure that he could remove such

QRM
as it.

Usually a fence has HV pulses generated by a large ignition coil or

similar
transformer or this is maybe a thermostatic device

I see three solutions:
- I 'd like to know if there is a way to install on the fence itself a
"de-parasiter", something like a low-pass filter that 'd cut all trancient
emissions in HF bands ?
- or could the MFJ noise canceller (MFJ 1025/1026) be a solution

(tightening
a second antenna like a long wire 20m long outdoor)
- at last is there another model of receive antenna that could really

reject
this kind of QRM ?

Any other idea or an URL ?

Thanks in advance

Thierry, ON4SKY
http://www.astrosurf.com/lombry



I forget where I saw it (maybe in the MFJ catalog) - but I've seen a device
used for cancelling unwanted signals.
I think the principle is that the second (smaller) antenna should pick up
the unwanted signal -and have an attenuator on it - it adds to the original
signal, but in opposite phase so as to cancel.
Used mainly to block locally strong signals so you can hear remote weaker
signals.
The second antenna - being smaller - only picks up the strong local signal.
---
HTH
Hal


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