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Re: LF: RE: Top-fed LF antenna idea

To: [email protected]
Subject: Re: LF: RE: Top-fed LF antenna idea
From: [email protected]
Date: Fri, 23 Jun 2006 19:16:42 EDT
Delivered-to: [email protected]
Reply-to: [email protected]
Sender: [email protected]
In a message dated 23/06/2006 17:22:09 GMT Standard Time, [email protected] writes:
Dear Peter, LF Group,

As I recall, G0MRF's first trans-atlantic transmission was done from the top
of a tower block with a down-sloping wire as "top loading" - Perhaps David
would care to fill in the details...

Cheers, Jim Moritz
73 de M0BMU
Hello Jim / Peter.
 
I thought of the transatlantic contact when I read your post. However the comparison to the EH antenna is a difficult one to make. In my case I was trying to construct a center loaded dipole using 250 foot elements, or about 12 degrees at 136k, with the feed point perhaps 180 feet above ground.  In the event, the dipole proved very difficult to resonate and I eventually settled for paralleling the two 250 ft wires and feeding them against the several kilometres of copper water pipe running through the building.  That worked very nicely with good QRSS3 signals visible in VO1 with RF down to 300W at the TX site.
Sadly that building was demolished 2 years ago, so no opportunity for another visit.
 
 
Unfortunately I never did manage to get my dipole working.  However, 6 years later my homebrew N2PK vector network analyser is nearing completion and later this summer I hope to 'borrow' some land on very poor earth and finally put up a full size dipole and make some serious measurements. (The poor earth is a key factor in the master plan! ) Will it work? - who knows! Certainly the scale model on 21MHz positioned 50mm above my lawn made it to a rather incredulous amateur in Romania.
 
Regards
 
David  G0MRF
 
 
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