[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

EchoTelemetry Setup - Dual

 I successfully got two telemetry capture sessions running at the same time
on the same machine. (WinXP, Celeron 550 mhz, 256 mb ram)

Setup 1: Dual band (2/70cm) Arrow J-Pole @ 60' > Comet 2/70cm duplexer >
Kenwood D7A(g) > Serial RS-232 > TLMEcho (Com1) (The 2m side from the
duplexer goes to my aprs setup on 144.390 and has nothing to do with sats)

Setup 2: M2 CP-30 RHCP @ 8' > FT-847 > MixW32 > MixW Port Emulator LoopBack
> TLMEcho

The signals from the RHCP CP-30 largely stink, as a result of ECHO being
LHCP on the telemetry downlink.

During the next week, I will be changing to the following setup:

Lightning Bolt 4 el (2m) / 8 el (70cm) nested rear mount quads > 70cm preamp
> Comet Triplexer @ antenna mast (6m/2m/70cm) > 80' LMR-400 > Comet
Triplexer @ shack (6m/2m/70cm) > FT-847.

This gives me linear polarization for ECHO and other uses, on a single
feedline, with the in shack Triplexer feeding the FT-847 seperate connectors
on the back. I have a 6m antenna on the same Oscar stack outside, so it's 3
for 1! This also should help with Mode J desense problems. (If need be, I
can put another duplexer in front of the 70cm preamp and terminate it's 2m
input with a 50 ohm resistor, using it as an additional filter)

The Comet Triplexer is spec'd at < .25 dB loss at 70cm with port isolation
of 55 dB. It would be nice if these values are in the ballpark and not just
marketing hype.

The Lightning Bolt dual band quad is nicely constructed, very easy to
assemble (if you remember to mount the 70cm elements first!!!) and should be
quite adequate for ECHO and other LEOs. This is two quads with separate
feeds on the same boom, with the 70cm 8 elements nested inside and in
between the 4 two-meter elements. I wouldn't believe any antenna gain claims
for these antennas, but suffice it to say they should do an adequate job.
The boom is 44" long and has a rear mount. The feeds are UHF SO-239
connectors for both bands, nothing special. All the 70cm elements come pre-c
ut and mounted to the spreaders.  I'll report on its performance as soon as
I get it re-assembled (mount the 70cm elements first, folks) and put up,
perhaps this evening. I am going to start using vertical polarization,
simply because it will let me test the array using readily available 2 and
70cm repeaters. It will also let me compare the 8 element 70cm quad to my M2
CP-30 RHCP 70cm antenna, which has a known gain of 14.5 dBc.

The FT-847 power control is very easy to back all the way down and run less
than a watt output, btw. I also have an M2 2m EggBeater on the same cross
boom. Eventually, for LEOs, I'd like to have both 2m and 70cm Egg Beaters
with preamps as the main setup, and use the dual band quad and M2 CP-30 for
the higher orbit birds. For now, I'm going to use the dual band quads
extensively, so I can determine just how well they might work for both Mode
B and J birds, as well as future high orbit satellites.

For those who might ask the question...sheesh, why didn't you just buy the
circularity switch for the CP-30? Economy: the dual band quad was 80 bucks,
and gives me a lot of potential functionality and added flexibility. The
polarity switch for the CP-30 is 170 bucks, and doesn't give me two new
antennas to play with <grin>

...hasan, N0AN
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