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 hf rcv ant.. 
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Post hf rcv ant..
Thinking of a receive ant for my 1000mp to plug into the rcv ant socket,,any info help would be appreciated,cheers.Rob M0PTT.


Wed Sep 13, 2017 6:00 pm
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 hf rcv ant.. 
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Post Re: hf rcv ant..
It depends what you want the receive antenna to do, that the existing antenna doesn't.

There are a few reasons why a separate (i.e. 'different type of') antenna might be better.

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Wed Sep 13, 2017 10:24 pm
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Post Re: hf rcv ant..
For 160, 80 and 40mtrs I run a pair of 1 mtr diameter loops at 90 degrees to each other feeding a low noise, balanced high dynamic pre-amplifier.

For rx I can switch between loops and the 201 foot doublet I use on tx.

More often than not one of the loops provides a better rx signal than the doublet by quite a large margin.

The loops are only 1.5 mtrs agl but are placed as far away as possible from the house and doublet.

73 Tim

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G8GIW licensed in 1972 (C&G RAE), then G4WIM in 1984 (12 wpm CW test), then KT6UK in 2000 (USA Extra Class), now safely back in the UK and retired early (Google bought the company I was working for !)


Mon Sep 25, 2017 2:38 pm
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 hf rcv ant.. 
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I wish I knew more about this, but it does seem to be fact that 'magnetic' (loop) and soft-terminated 'travelling wave' (T2FD) antennas are superior to resonant 'Hertzian' antennas on receive.

The Wellbrook-type loop is already highly-regarded, and a while ago on this site we had a few people say that they got great noise-cancelling results with quite small T2FDs.

Why this should be, I don't know. Why an antenna should accept one type of signal and reject another beats me, and I need to 'imagine' a third ('percussive') polarization in the transition and far fields which physics says does not exist.

It's at times like this that you realize something is missing from this board ....

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Mon Sep 25, 2017 3:32 pm
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 hf rcv ant.. 
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Post Re: hf rcv ant..
this might help http://www.n6rk.com/loopantennas/pacificon.pdf

my rx loops have 8 turns in parallel for each loop but are untuned and instead feed into a push pull balanced pre-amp.

Supply voltage down the coax from 10 to 14V selects one loop 15V and above selects the other loop.

When on tx there's no supply voltage and the pre-amp inputs get grounded

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G8GIW licensed in 1972 (C&G RAE), then G4WIM in 1984 (12 wpm CW test), then KT6UK in 2000 (USA Extra Class), now safely back in the UK and retired early (Google bought the company I was working for !)


Mon Sep 25, 2017 5:15 pm
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Post Re: hf rcv ant..
I have recently purchased a second hand Wellbrook ( 1m dia) active loop antenna which works very well. These loops cover 50KHz to 30MHz and I have been very pleased with it's performance on 160, 80, 60, 30 and 40m. However, so much depends on where your noise sources are and also general propagation. Generally my 204ft double sized G5RV tends to give better results on inter G in the evening on 160m but the Wellbrook sometimes has the advantage on longer haul stations to the east.

The same on the other bands; sometimes the doublet can prove quite good then other times the Wellbrook has the advantage.

I run a beam on HF so I do not need the loop; however, I have been very impressed with just how good it is between 14MHz to 30MHz when the bands have been open.

The Wellbrook is a very good all round receive antenna, but not cheap when bought new. It is important to place it well away from houses and also your TX antenna for best performance. I am fortunate in that respect as I have it placed down the far end of my next door neighbour's garden!!!

More information can be found on Wellbrook's web site; Google "Wellbrook receive loop".

Hope this helps.

73's Vince G3TKN (Waterlooville, Hants)


Tue Oct 03, 2017 12:16 pm
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