Antenna designs for noise cancellation on HF bands
cliff wright
(especially 14 MHz) for use in a situation with a lot of QRN.
This seems to be radiated from local power lines, but despite the lnes
in our subdivision being underground we still get a S6/S7 noise level.
Yes we have contacted the authorities but so far no useful result.
It seems somewhat worse on my 5/8 wave vertical than on my G5RV doublet.
Neither myself no a neighbouring Ham have been able to find a way around
this problem despite us both being experienced "old timers".
Some sort of "noise antenna" and phasing arrangement is contemplated but
we have not as yet found a suitable design.
Any ideas welcome!
73's Cliff Wright ZL1BDA ex G3NIA
Helmut Wabnig
I love Googel links!
Try a magnetic loop antenna, they are less suszeptible to noise.
w.
John, N9JG
http://www.dxengineering.com/ProductDetail.asp?ID=215&SecID=114&DeptID=12
John, N9JG
"cliff wright" <c.c.w...@paradise.net.nz> wrote in message
news:4782085f$1...@clear.net.nz...
Hal Rosser
I have not tried it myself, but MFJ makes a noise cancelling doo-dad called
the MFJ 1026.
http://www.universal-radio.com/catalog/preamps/3541.html
Ian White GM3SEK
Chip Angle, N6CA, presents some very interesting ideas for a 50MHz noise
cancelling system at: http://tinyurl.com/22gqab
The circuits for phase adjustment, gain control and summing
(cancellation) should all scale easily to HF. However, the noise can
only be cancelled completely if it behaves like a signal originating
from single point. Noise from power lines may be arriving with a spread
of amplitudes and phases.
--
73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek
Sum Ting Wong
<c.c.w...@paradise.net.nz> wrote:
>Any ideas welcome!
Get yourself a portable VHF radio that receives AM and use a handheld
Yagi to trace down the noise. Powerline interference is much easier to
DF at VHF. Pull the main breaker on your house to make sure the noise
isn't being generated within your residence. Here in the USA, the
power companies are obligated to eliminate interference emanating from
their equipment, but don't know about ZL. It never hurts to ask. The
power companies up here have very skilled folks who track down
powerline interference complaints.
Good luck with finding the source.
S.T.W.
cliff wright
Been There Done that!!!
Yes OM we've tried all sorts of search receivers and antennas. Had some
success in locating some vey poorly maitained insulators in a 32Kv
overhead line about 500 metres from our 2 QTH's. Problem is the liabilty
for interfernce is very poorly defined here in NZ. The power generating
companies and line companies are separate and poorly coordinated as a
result of abortive privatisation in the 1980's an 90's.
We have our people from our Trade and Industry dept involved already.
These are the equivalent of our Radio Inspectors of earlier times and
are of some help.
However we are now both concerned that the interference may be carried
or even caused by faulty earthing arrangements in our local underground
"neutral earthed" system. I am a registered electrician and my fellow
Ham is actually employed by a lines company.
So much for my nice electrically quiet section on a hilltop for my
retirement!!!
However I will follow up some of the pointers which have been suggested
and hope that now the main summer holidays are coming to an end down
here some maintenance work will get done.
73's Cliff Wright