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Re: Re: Helix antennas,



That Ramsey preamp kit looks like fun. I've never built anything like
that, looks like a good first project. :) Cheap, too. They have them
for 144, 220, and 440, $14.95 US each. Thanks for the tips.

Zach KE7EYQ


On 5/15/06, k5oe@aol.com <k5oe@aol.com> wrote:
>
>
>
>  OOPS, that was the $17 Ramsey unit, not hamtronics.  Like Paul, I also
> replaced my ARR with a Landwehr and was muchhappier (same issue, wideband
> noise teneded to overload the preamp in some directions...cell towers, I
> think).
> 73,
> Jerry
>
> -----Original Message-----
> From: K5OE
> To: ke7eyq@gmail.com
> Sent: Mon, 15 May 2006 04:12:11 -0400
> Subject: Re: [amsat-bb] Re: Helix antennas,
>
>
>
>
>
>
> Zach,
> Any of the commercial ones will work well.  I have used ARR, Mirage, and
> Landwehr, they all worked fine, but I like the Landwehr the best.  If you
> are looking for bang for the buck, try the $17 Hamtronics kit.  You will
> need to add an enclosure and a relay (unless you trust yourself NEVER to
> transmit into it).
> 73,
> Jerry
> -----Original Message-----
> From: Zachary Schrempp <ke7eyq@gmail.com>
> To: k5oe@aol.com <k5oe@aol.com>
> Cc: amsat-bb@amsat.org
> Sent: Sun, 14 May 2006 14:39:45 -0700
> Subject: Re: [amsat-bb] Re: Helix antennas,
>
>
> For those of you using preamps, which kinds do you find to be the best
> bang for the buck on 144 and 435 MHz, and where do you usually
> purchase them...or do you homebrew them?
>
> Zach KE7EYQ
>
> On 5/14/06, k5oe@aol.com <k5oe@aol.com> wrote:
> > Zach,
> >
> > > Thank you all for your input. It is nice to have so many helpful
> > > people give antenna advice.
> >
> > One of the things AMSAT members are best known for is giving people advice
> :-) Seriously, Steve's reference to Kent's Cheap Yagi is a good choice for
> the current fleet of LEO's. They are easy to build and tune and have the
> simplicity of a linear design. Any pair of Yagi's in the 3-5 elements range
> are more than good enough for all the LEOs. Adding at least a 70 cm preamp
> (at the antenna) is always the best money you will spend.
> >
> > Save the helix effort for 1.2 GHz and up: I no longer have the page on
> web, but I built and used a 70 cm helix based on the AF9Y design (I used an
> aluminum pan for the reflector :-)) and found it fine for transmit, but not
> a good receive antenna for that band. The reason? By it's nature the helix
> is very widebanded (thank you Dr. Kraus), a real convenience when building a
> transmit antenna, but not so good for receive selectivity. I found the
> wideband UHF noise allowed into the receiver (amplified by a wideband UHF
> preamp) to greatly degrade receive perfomance.
> >
> > Many people enjoyed success with helices on AO-40, including me, but that
> was a few years ago now and things have changed considerably since then. The
> explosion of WiFi sources very near the 2.1 GHz band may very well have
> changed the spectrum profile enough to make a helix+preamp unusable in any
> densely poplulated area below 15 or 20 degrees elevation. For S-band
> downlink on P3E and Eagle, I would suggest a narrow-banded antenna/feed such
> as a patch or Yagi is a better choice. For uplink on 70 cm or L-band, a
> helix is still a great choice. FWIW, I employed a pair of concentric helixes
> for L/S on a 4' dish for about 6 months and they worked fine. I replaced the
> helices with the dual patch feed now shown on the web page and was much
> happier with that arrangement (better s/n, the real difference).
> >
> > 73,
> > Jerry, M0MOE
> > ----
> > Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
> > Not an AMSAT member? Join now to support the amateur satellite program!
> > To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
> >
>
> -- Zachary Schrempp, KE7EYQ
> AMSAT #36023
>


-- 
Zachary Schrempp, KE7EYQ
AMSAT #36023
----
Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
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