Height should not be the problem.
My 2-element HyGain discoverer did not change its SWR when taken down from
38m to its present 18m height.
73
Peter
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Roger
Cooke G3LDI
Sent: Dienstag, 2. Dezember 2014 21:20
To: towertalk@contesting.com
Subject: Re: [TowerTalk] 402CD
Hi.
Many thanks to all who replied. I have kept all the emails and it
looks like there are a couple of
possibilities.
1 The loading coils are not making proper connection, some
corrosion may have crept under the
insulating sleeving covering them. This seems a common fault so I
will be having a look at those.
2 A couple of you suggested that it could be too low. I have it
installed on a 70ft crank-up tower
which I have to finish roping as yet in order to crank it up. I'm
not sure if this would have accounted for the 3:1 SWR, which seems
very high to me. My linear would baulk at that!!
I did clean the beam thoroughly before putting it up and I used
aluminium graphite anti-seize
compound on the elements when assembling it. I used a 1:1 toroidal
balun at the feed point and
I used Westflex 50 ohm low-loss coax.
Thanks again to all who replied and I will follow up on all the
suggestions. Hopefully they will
work out! I shall crank the tower up to 70ft before testing again.
Even that is low for 40m I do
realise! I am just too much of a coward to stack it above my 4-el
steppir which is on my 120ft
tower. I guess it might be an idea to swap them around!!!!
73 de Roger, G3LDI
On 01/12/2014 14:41, GC wrote:
> Hi Roger,
> Take a look at this article from KA9FOX from a few years ago. I
> had the 402CD as well and re-did the connections on the coils.
> I've got the XM version now and it's done well for me through the
> years.
>
> 73/Greg
> K9IG
>
> http://www.qth.com/ka9fox/40-2cd_trap_fix.txt
>
>
> --------------------------------------------------------------------
> *From:* Roger Cooke G3LDI <roger@g3ldi.co.uk>
> *To:* towertalk@contesting.com
> *Sent:* Monday, December 1, 2014 7:20 AM
> *Subject:* [TowerTalk] 402CD
>
> Hi.
>
> I am trying to get a Cushcraft 402CD to work. It was given to me by
> somebody who had stored it for
> a considerable time in his garage. I assemble it, using some lube
> on the aluminium joints etc and
> checked all measurements. I fed it with a velocity corrected piece
> of coax via a 1:1 balun and put
> it up. It is only at about 30ft, but the resonance is around
> 6.8MHz and the SWR is about 3:1.
>
> I think it should be much better than that, but can't find any
> problem with it. I am now suspecting
> the loading coils and their connections. Although the insulation
> looks fine, has anybody else had
> problems with these? I am clutching straws now!!
>
> 73 de Roger, G3LDI
> _______________________________________________
>
>
>
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> TowerTalk@contesting.com <mailto:TowerTalk@contesting.com>
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>
>
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