I've owned three TH7DXs, first one in 1978. #1 & #2 were made by
HyGain, it's now made by MFJ. I think that before that Telrex made them
and as far as I can tell they are mechanically identical. I think there
may have been some tweaks to the feed balun, but am not sure. I now
have a brand new Telrex made model I picked up at an estate sale, but
mice ate the original shipping boxes (NINB - new in no box?). I don't
think it is fair to characterize it as log periodic, since the directors
and reflectors are trap tuned (or unique) to each band. It does have
two driven elements for broader bandwidth. My first two survived
several Massachusetts hurricanes and worked well.
Grant KZ1W
On 3/29/2012 5:54 PM, Mike Newman wrote:
> Hi all
>
> Looks like there are a few models called Thunderbird.
>
> The one I'm enquiring about has a diagram entitled
>
> TH11DX 5 band (14 - 30 MHz) Super Thunderbird Yagi Antenna.
>
> It has 11 elements. It's probably a log-periodic in part with other
> elements interleaved, all on a 24 ft long boom.
>
> An operator here has one, and we are using it as an example in an
> planning dispute.
>
> Can any one on this list tell me approximately when this antenna was
> first marketed, and whether the design has changed over the years?
>
> 73 de miken, zl1bnb
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