[amsat-bb] Re: Antenna Opinions?
w7lrd at comcast.net
Tue Sep 21 23:32:52 PDT 2010
Hi Greg et al
I have been partial with the helix for satellites. I run 10W to a 16 turn helix through 40 feet of LMR-400. I rarely have an issue getting into AO-51. I believe AO -51 is our only L band bird, I try to "exercise" my gear when the opportunity is there. I experience very little fading with the L band uplink, input to the satellite is quite solid down to fairly low elevations. The yagi would as you mentioned would better for terrestial 1.2ghz stuff.
73 Bob W7LRD
----- Original Message -----
From: "Greg D." <ko6th_greg at hotmail.com>
To: amsat-bb at amsat.org
Sent: Tuesday, September 21, 2010 10:03:31 PM
Subject: [amsat-bb] Antenna Opinions?
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?
Sent via AMSAT-BB at amsat.org. Opinions expressed are those of the author.
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