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[TowerTalk] Re: Log periodics - Tennadyne

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Subject: [TowerTalk] Re: Log periodics - Tennadyne
From: (DavidC)
Date: Sun, 14 Jun 1998 13:49:08 -0400
> Hi -- did a search on tennadyne and found no listing for the
> manufacturer, maybe it is in QST.  Did get a number of hits showing that
> tennadyne antennas were used in some 'contesting' station descriptions.
> Here is the URL for the Telex/Hy-Gain beam listings.  It is sort of
> deceptive, for the best ones they make are WAY down at the bottom.
> Maybe you can get the LP-1010 and blow everybody away!  It covers 10-30
> MHz.  If they make one which also covers 40, or 40 and 80, it is not
> listed on their pages.
> Again, please let me know what your research produces, too.  This
> subject is of much interest to me.  I would like to know if TennaDyne
> has a website.  Searching TennaDyne produced nothing -- tennadyne got me
> the hits.  73-
> Regards,  Mike


   I found a couple of sites and a couple of discussion list commentaries
that seemed particularly helpful.  I'd love to find a good comparison
between the log periodics, one might then compare them to mono-banders,
tri-band yagis, and quads.

   Hope this helps!  73, DavidC  AA1FA

Here are two sites:

Key Comments I Found:

I reverse-engineered the T-10 and found it to be a good design except for
the feed impedance. When I spoke to the designer, he claimed that you could
indeed have a 50-ohm feed with a circular-cross-section 2-line boom feed.
That was my first clue that he really didn't understand the design and
couldn't help me with the poor SWR.

Finally, remember that anything within a boom's length of a log will skew
everything. I put a 40-2CD above it and varied the separation distance
until the log's SWR was okay.

Robert L. Hummel (WS1A)

tom loebl wrote:
> Looking for a multiband beam and I am wide open on the type and size. I
> have been looking at the T10 10 element LP or possibly the T12. Also
> considering the TH11. Any comments are appreciated.
> Tom WA1VTA

Hi Tom,

I have a Tennadyne T-10 Eagle at 72'. It has been up about six years and
has been through at least that many ice storms. It is absolutely amazing
how well it has stood up to ice and wind at the same time.
Mechanically it is superb and not too heavy (which seems contradictory, but
given what it has gone through here in Iowa, I'm very impressed with its

I have measured its F/B with a calibrated attenuator and it maintains its >
17 dB F/B over the entire frequency range as far as I could ascertain.
Forward gain is probably about 6 dBd. I get who I call with 500w. VSWR is <
1.8:1 at the very worst (a few isolated frequencies in its 13-30 mhz
bandwidth). Over the vast majority of frequencies VSWR is < 1.5:1. It is
dead flat on several amateur bands.

I have an array of 2x22 el 70cm and 1x12 el K1FO yagis mounted on an
elevation rotor about 7 feet above the LP.

One piece of advice:

1. The shorting wire at the back of the two booms that was being provided
is just a length of #18 wire. I didn't like that. I bought a piece of
aluminum welding rod, bent it into the same shape (a nice looking rectangle
open on the boom end) and put it on in place of the feeble looking wire.

I measured the VSWR on 30m and it is about 2:1. I fed it with a tuner and
it worked as well or better than a double extended zepp for the same
frequency. I even loaded it up on 40m when I was desperate during a contest
and worked several African and European stations. Not a very good solution,
but at least it wasn't just a dummy load.

Overall, I strongly recommend the antenna for its ruggedness without being
heavy and for its F/B and excellent VSWR bandwidth. LP gain is, of course
somewhat less (perhaps 1.5 to 2.0 db) than a yagi on a comparable boom, but
you lose the frequency agility.

73  hasan, N0AN

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