I would start with a visual inspection of the traps on the driven elements.
Remove the screw that secures the sleeve to the element and then slide the
sleeve to expose the coil and coil form. If/when you find a damaged coil be
sure and check the other 3 for that band as they are probably all burned.
Our club's TH3-jr had similar symptoms and I found the insulator had carbon
traces from an arc - high power applied to a low power antenna. I removed
the wire from the form, cleaned the carbon from the form with a brush and
isopropyl (sp) alcohol, rewound the coils with new wire and everything works
fine now.
I have found that Hygain is real good on replacement parts.
de Paul, W8AEF
----- Original Message -----
From: <Rnlamm@cs.com>
To: <antennaware@contesting.com>
Sent: Tuesday, August 30, 2005 12:47 AM
Subject: [Antennaware] TH7DX 15m high swr
>I first noticed that my TH7DX was not hearing as well as my other 15m
> antennas. The TH7DX does not resonant on 10/15m but works fine on 20m. SWR
> at the ant
> is >3/1 from 21.0 to 21.9mhz, then decreases to 1.7/1@22.3mhz and back to
> 3/1
> at 22.9 mhz. On 28mhz: SWR is 2/1 from 28.0 to 29.0mhz. The balum was
> removed
> to collect this data. Does anyone have a systematic approach to
> determining
> which trap or etc is the source of the problem. Hygain tech support was of
> little assistance. Thanks in advance for your reply.
>
> Russ - NN3Q
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> Antennaware@contesting.com
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