[TowerTalk] TH7 installed but not resonant

[W5XB]

Thanks, Jim, Bob, and Jim H.,

Excellent suggestions all. I will summarize these and give 
them all to him before he goes up the tower.

Thanks guys, these were just the kind of ideas I was looking 
for.

Cheers all around,

73s,

Grant
W5XB


----- Original Message ----- 
From: "Jim Hargrave" <w5ifp at gvtc.com>
To: "W5XB" <w5xb at att.net>
Cc: "Towertalk" <towertalk at contesting.com>
Sent: Sunday, November 20, 2011 5:52 PM
Subject: Re: [TowerTalk] TH7 installed but not resonant


> Grant,
>
> I would be concerned about the bolt. It could be shorting 
> something out.
>
> I would also have him check the straps from the balun to 
> the driven element.
>
> Also make sure the coax has not pulled out of the 
> connector on the balun.
>
> Its also possible the link between the two driven elements 
> was bent and
> shorted together during installation. These tubes cross 
> over between the
> elements.
>
>    73s de Jim
>       W5IFP
>
>
>
>
>  > -----Original Message-----
>  > From: towertalk-bounces at contesting.com
>  > [mailto:towertalk-bounces at contesting.com]On Behalf Of 
> W5XB
>  > Sent: Sunday, November 20, 2011 3:02 PM
>  > To: towertalk at contesting.com
>  > Subject: [TowerTalk] TH7 installed but not resonant
>  >
>  >
>  > Looking for help on my "new to me" TH7DX.
>  >
>  > Was not used couple of years, cleaned it up, read and 
> used the
>  > manual, put it together, and put it on top of an 
> asphalt
>  > shingle roof at 25 ft.
>  >
>  > Checked with MFJ analyzer, and found it resonant low, 
> about
>  > 13.7 Mhz as expected. The other bands were low too, but 
> 10 m
>  > was about 2:1. It "heard" almost as well as the TA33. 
> Figured, all ok.
>  >
>  > Due to back injury (lawn mower accident!) can't climb 
> right
>  > now, so I had an installer take the TA33 down and put 
> the TH7
>  > up on 65' self supporting tower with no surrounding 
> obstacles.
>  >
>  > Now the antenna is not resonant anywhere. Best SWR is 
> 9:1 at 14
>  > Mhz, resistance is 10 ohms, x=57. Coax checks with .9 
> db loss.
>  > The "hearing" is now about nil, like a wire hooked to a 
> piece of coax.
>  >
>  > Have looked at the antenna with binoculars. The attach 
> points
>  > for both driven elements look as they should, but I 
> can't see
>  > the gamma match from the ground.
>  >
>  > The installer is not familiar with the TH7, but has put 
> up
>  > dozens of SteppIrs, and monobanders. He did mention 
> something
>  > about "adding a bolt near the Gama match tubes" ... not 
> sure
>  > what he did. Boom support is Philly Strand.
>  >
>  > Will of course show installer, the assembly manual and 
> ask
>  > about the added bolt.
>  >
>  > Installer is coming back Monday afternoon to check out.
>  >
>  > Any clues about what to check, greatly appreciated!
>  >
>  > Many thanks and 73s,
>  >
>  > Grant
>  > W5XB
>  >
>  >
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>  >
>  >
>  >
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