[amsat-bb] Re: Antenna Opinions?

Steve Niles n5en at wt.net
Wed Sep 22 06:34:07 PDT 2010

I use a Directive Systems 25 element loop yagi and it works great for AO-51 L band.  http://www.directivesystems.com  I'm feeding it with 10 watts via 35 feet of LMR400.  Directive Systems antennas are very well built and less expensive than some other popular brands.

Steve N5EN

--- ko6th_greg at hotmail.com wrote:

From: "Greg D." <ko6th_greg at hotmail.com>
To: <amsat-bb at amsat.org>
Subject: [amsat-bb]  Antenna Opinions?
Date: Tue, 21 Sep 2010 22:03:31 -0700

Hi folks,

So, we had a swap meet a couple of weekends ago, and I found a bargain I couldn't refuse.  Of course, now I need to decide what to do with it...  

The Find was a 35 element 1296mHz antenna, well built and in excellent condition.  Linearly polarized, horizontal; supposed to be 23dBi gain.  Manufacturer, of course, is unknown.  No markings, but it does not look home-built.  By the mounting hardware, it looks like it was part of some sort of stacked array.

The problem is that I already have a 1296mHz antenna.  Home-made, circularly polarized, 18 turns Helix.  Should be something like 17dBic, if the calculations are correct.

In the shack, which is at the wrong end of 60' of 1/2" hardline and a total of about 15' of RG-213 or something like it, I have my Yaesu 736R and its 10 watts of screaming RF power.  No preamps.

Which antenna should I keep up on the rotor assembly?

Last weekend I put up the new antenna.  I've made one AO-51 LU pass with the new antenna, and I was not impressed.  Several times I couldn't get into the bird, presumably because of the crossed polarization.  But when I did get in, it was full quieting, even at low elevations.  I don't recall having this much trouble with the Helix.  I think AO-51 is the only current satellite on L-band, right?

For other uses, there's nothing terrestrial to aim at, repeaters-wise; they're all hiding behind one or more hills, or went off the air years ago.  That leaves Weak Signal work (hence the horizontal mounting).  I do have one shot into the valley, to the North West, but probably slim pickings for contacts.  I haven't tried EME.

I'm leaning towards putting the Helix back up, and passing the new one on to someone more able to use it.  What are your thoughts?


Greg  KO6TH

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