[amsat-bb] Re: New Lindy's QRV

Bill Dzurilla billdz.geo at yahoo.com
Tue Feb 9 06:23:18 PST 2010


I would be suspicious of the construction.  I can get a few minutes of good copy from AO-51 on a high pass with just a rubber duck on an HT.  If you do get a preamp, the run between the antenna and the preamp is critical, so if possible keep it short and use good coax.  Ed seems to be having success with 4' of RG-58U, but generally the use of any RG-58U at 70cm is not a good idea.

Here's a quick summary of my results with various antennas:

* HT and rubber duck or other antenna mounted directly on the HT - success only at high elevations
* HT and Arrow or Elk antenna, no preamp - success from horizon to horizon, if no trees or other obstructions
* base rig and dual band omnidirectional ground plane, no preamp, 40' of RG-213U - success on most birds only when elevation is above 25-35 degrees
* base rig and dual band omnidirectional ground plane, ARR preamp, 40' of RG-213U - success on most birds when elevation is above 15 degrees
* base rig and Elk antenna on 12' pole at 15 degrees fixed elevation, azimuth rotation with old TV antenna rotor, ARR preamp, 70' coax run (my current setup) - full success from horizon to horizon on all birds, except in directions where blocked by trees or roof.

The Elk is $135 shipped and the used rotor was $25, and this combo is by far the most effective I have used.  My community has antenna restrictions, but so far no one has complained about the little 2' long Elk.  The Elk could be replaced with a homebrew Cheap Yagi or tape measure yagi, which can be built for $10.

I am not aware of anyone who is able to work the sats at low elevations with any type of omnidirectional antenna, even with the best preamp.  You can have plenty of fun working the birds at higher elevations, but you will be able to work more passes and better DX (e.g., Europe on AO-7) if you can catch them at lower elevations.

73, Bill NZ5N 
> Date: Mon, 08 Feb 2010 17:26:11 -0700
> From: David Ek <dave at eksfiles.net>
> Subject: [amsat-bb] Re: New Lindy's QRV
> To: amsat-bb at amsat.org
> Message-ID: <4B70ABA3.9090908 at eksfiles.net>
> Content-Type: text/plain; charset=ISO-8859-1;
> format=flowed
> Question for anyone out there: I just built the parasitic
> Lindy from the 
> Feb 2010 QST. What kind of performance (on receive) should
> I expect from 
> it during, say, an AO-51 pass (max EL 83 deg)? I had my
> Kenwood TH-F6a 
> HT connected directly to it (only a few feet of RG-8X coax
> to the 
> antenna) with no preamp, and I only had good copy for a
> moment here and 
> there. Just wondering if I need a preamp or if I need to be
> suspicious 
> of my construction.
> tnx & 73,
> Dave NK0E
> -----------------
> Edward Cole wrote:
> I forgot to add that these are patterned after Tony, AA2TX,
> designs
> (UHF version is in Feb. 2010 QST).
> My variation was to use pvc sched-40 plastic pipe (white).
> The preamp is one of the older DEMI designs that uses a
> mgf-1302
> GasFet with about 0.7 dBNF.  I see about one s-unit of
> noise when I
> turn it on.  There is 4-feet of RG-58 to the UHF Lindy
> and 60-feet to
> the FT-847 from the preamp.  The VHF Lindy has no
> preamp and is fed
> with 60-feet of RG-213.
> The VHF Lindy brings up repeaters 70-miles away with 50w,
> and the UHF
> Lindy hears repeaters that far away.  So actually can
> make a nice
> general purpose antenna.
> 73, Ed


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