I have one of the Original AMSAT Broadband Satellite RX Preamps which has quit
functioning. I have checked most of the components and everything looks normal
except there is a large loss of signal instead gain. I suspect the
Mini-Circuits MAR-07 has failed. Both Mouser and Digikey list the part
Perhaps it’s just me, but it seems like an increasing number of operators are
trying to find their downlink by speaking into their mic while tuning up and
down the band, often plus or minus 20-30 kHz. Not only is this disruptive to
existing QSOs, it is not the most effective way to do it. My
Using the keps from this morning (epoch 1.066), I measured the frequency of
the telemetry signal of AO-73 during a 43 deg pass at about 1648 UTC (Nov 29).
This is a pass with the satellite in the sun
The frequencies are the frequency “at the satellite” calculated by SatPC32 to
place the
Using the keps from this morning (epoch 13331.102), the Doppler corrections by
SatPC32 are slightly closer than yesterdays keps. I got the following
frequencies from a 40 deg pass about 1739 UTC.
The frequencies are the frequency “at the satellite” calculated by SatPC32 to
place the center of
The keps from this morning (epoch 13330.154) brings the sat LOS a little early.
I was clearly hearing the telemetry down to –1.0 deg after “LOS”. AOS, of
course, a little late.
Ron W5RKN
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Sent via AMSAT-BB@amsat.org. Opinions expressed are those of
Using the keps from this morning (epoch 13330.154), the Doppler corrections by
SatPC32 are much closer than yesterdays keps. I got the following frequencies
from a nearly overhead pass about 1722 UTC.
The frequencies are the frequency “at the satellite” calculated by SatPC32 to
place the center
On the nominal 0015 UTC pass over Texas, the ARISSat-1 telemetry seemed normal
but at about 4-5 minutes before LOS, the frequency of the CW marker and the
BPSK telemetry envelope started dropping very rapidly. I lost track how many
times I had to adjust the Doppler-corrected frequency down by
Forgot to note the altitude give by the most recent keps was 175 km.
Ron W5RKN
From: Ronald G. Parsons
Sent: Tuesday, January 03, 2012 6:27 PM
To: AMSAT-BB
Subject: Rapid frequency change on ARISSat pass
On the nominal 0015 UTC pass over Texas, the ARISSat-1 telemetry seemed normal
On the just concluded pass of ARISSat, all the KURSK frames I copied were all
zeros (except for the header).
Is there a problem or a change?
Ron W5RKN
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Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author.
Not an AMSAT-NA member?
A couple days ago, I noticed that to get a 500 Hz signal for CW-2 (nominally
145.9190 MHz) to decode the BPSK-1000 signal, I had to change the
unDoppler-shifted frequency on my USB receiver from 145.918500 MHz to
145.918280 MHz, a change of 220 Hz.
This new value have been consistent over a
One thing I've discovered which makes things go more smoothly is to reduce
the minimum Doppler tuning interval.
I am using SatPC32 V12.8a. There are two parameters in the CAT menu -- the
Speed which I changed to 5x (which is not sticky) and the minimum Doppler
tuning step for SSB which I set
Last evening, after having several days experience capturing ARISSat telemetry,
I sat at my radio and watched carefully how SatPC32 and ARISSatTLM played
together. I had settled on a tuning correction value of –540 HZ to get the CW
signal to center around the CW tuning point as the Doppler
The ARISSat web site shows how to get a Reception Certificate for Voice ID,
Voice Telemetry, and SSTV.
I have screen shots of the BPSK-1000 reception and CW.
How does one claim a certificate for BPSK-1000 reception?
Ron W5RKN
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Sent via
My July/August 2010 issue of The AMSAT Journal arrived today and I was pleased
to see the article by Alan Biddle on Doppler Tuning. This has long been a pet
project of mine since Paul Williamson, KB5MU, published his article The One
True Rule for Doppler Tuning in the OSCAR Satellite Report,
I discovered this with my 910H. If you compare the schematic with an older
Icom transceiver, say the IC-756, you will notice that the voltage divider
on pin 8 decreases the audio on that pin by a factor of about 50 from the
IC-756!
I thought of two cures:
1. Modify the radio by replacing the
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