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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment. |
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29th Mar 2015, 9:14 pm | #21 | |
Heptode
Join Date: Jan 2008
Location: Ashhurst, Manawatu, New Zealand
Posts: 570
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Re: Aircraft Main Antenna - Quick Question
Quote:
The antenna is kept tight by the in-line tensioner - a spring under compression - between the insulator and the tail mounting. You can see one in the Dayton-Grainger advert with a 30lb spring.
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Cheers - Martin ZL2MC |
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30th Mar 2015, 9:48 am | #22 |
Dekatron
Join Date: Aug 2003
Location: near Reading (and sometimes Torquay)
Posts: 3,086
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Re: Aircraft Main Antenna - Quick Question
I think the main issue with wires like this is oscillation and resonance (not RF but mechanical!).
The wire needs to be the right stiffness and in the right tension to not vibrate itself to failure. The problem with a cylinder in a flowing fluid is that vortex shedding constantly "plucks" the wire to keep it vibrating. |
30th Mar 2015, 8:10 pm | #23 |
Dekatron
Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 8,173
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Re: Aircraft Main Antenna - Quick Question
Hi James, have you had a look at the stuff that Birkett's of Lincoln have?
Worth a mail to him in case he has an actual antenna; better still to have a visit and see the stuff in the flesh. Ed |
4th Apr 2015, 7:07 pm | #24 |
Heptode
Join Date: Jul 2009
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 722
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Re: Aircraft Main Antenna - Quick Question
Hi Ed
I came across his shop quite accidentally once when visiting Lincoln some years ago - it was shut but that seems to be not unusual! Lots of desirable goodies! Does he 'do' email? James |
4th Apr 2015, 7:49 pm | #25 |
Dekatron
Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 8,173
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Re: Aircraft Main Antenna - Quick Question
Hi James, I think he has an E-address and will normally respond within a day or so, but nothing to beat a visit and browse.
Ed |
4th Apr 2015, 8:41 pm | #26 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,801
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Re: Aircraft Main Antenna - Quick Question
John is probably best phoned.
David
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Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done |