[amsat-bb] Station not quite coming together - notes and request for advice
jonny290 at gmail.com
Tue Mar 6 17:19:08 PST 2007
OK, the situation is: I'm building up a satellite station to get familiar
with LEO sats and to get ready for the phase 3E fun to start soon. Here's my
station, and I'll post my thoughts after that.
Eggbeater II antenna mounted at 15 feet. This is built to the K5OE Eggbeater
II spec (http://members.aol.com/k5oejerry/eggbeater2.htm) but uses a 100 ohm
phasing line using two 50 ohm coax lines done in parallel, used in a
balanced configuration, instead of 93 ohm RG-62. Antenna was 'redesigned' in
MMANA-GAL to match exactly 100 ohms and to use 6mm diameter copper tubing
instead of AWG 12 house wire. It is peaked for SWR < 1.05 at 436 MHz, and is
less than 1.5 at 435.0 and 437.0.
Antenna is the secondary antenna on this mast and is mounted on a 3 foot PVC
stand-off pipe. The primary antenna is a Diamond F22A mounted at
approximately 18 feet. It has a 10.5 foot vertical element and three 1/4
wave horizontal radials. It is not used in the satellite station but I
wanted to describe it, in case it is interfering (I suspect it is.)
Eggbeater is fed through29 feet of 213 spec coax (5.1 dB loss/500 MHZ)
terminated in well done PL-259 connectors. I have verified this particular
cable's loss at less than 2 dB at 460 MHz, using my Icom PCR-100's accurate
S-meter and a known signal source.
My latest upgrade: RX chain goes into a homebrew relay / Ramsey preamp box.
The preamp provides approximately 18 dB of gain when inserted and using a
test signal around 432 MHz. It has proven somewhat beneficial, giving me 2-3
S-units advantage at certain points from the LO-19 CW beacon (Which I
recently received at up to S9 with the preamp on a ~60 degree pass).
IC-208H dual band radio, rated at <0.18 uV for 12dB SINAD
PCR-100 computer controlled receiver, rated at <0.34 uV for 12dB SINAD
More information about the AMSAT-BB