Re: [amsat-bb] 2.4ghz helix

["Edward R. Cole" <al7eb@xxxxxxxxxxxxx>]

>From: Bob W7LRD <w7lrd@juno.com>
>Hello
>With a Drake converter at the antenna with 60 feet of LMR-400 to the
>shack, what would be the  helix size want to be for  3D.  I will be
>building one soon.
>73...Bob...W7LRD
 
If you are using the Drake without a preamp [its noise figure is ~5 to 7
dB], then I would consider making a 20 dBi gain antenna to be safe.
However, my freind WL7BQM has a small dish (30 inch?) and heard the S1 and
S2 beacons fine with his Drake.  The LMR-400 is fine for the IF output
whether it is set up for 144 or 432.

This month's Amsat Journal has a fine article on making L/S Helix antennas
for P3D.  The author recommends making a 28 turn helix for 2400.  Joel,
K2SAT listed the parameters for making a 1269 helix just a few days ago on
amsat-bb.  Other references are "the Satellite Experimenters Handbook",
"Mode-S, the book", and "A 16 Turn S-band Helix" by G3RUH {ftp.amsat.org}.

Ed

al7eb@amsat.org - BP40iq
*************************************************************************
HF-50-144-432-1296-2400-10,368 MHz
Antennas: 4xM2-XP20, M2-436CP42, 23LY45, 5m & 2.5m dishes
cw, ssb, fm, psk31...APRS soon
Satellite:  analog modes  
eme:  144*-1296*-10,368*...*not QRV yet
microwave beacon:  10 GHz planned
Amateur radio astronomy & SETI:  1420-4000-10,370
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ARRL asst section mgr - Kenai Peninsula Alaska
MooseHorn ARC - president
Anchorage ARC - life member
ARES - member
SARA - member
SETI League - vol. coord for Alaska
AMSAT - vol. coord, Alaska
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Other interests:  Sled dogs, history

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