Hams in Space!

IC-475H. Most stations running about 25 watts
and up on AO-13's 70cm uplink (for Mode B)
were S-5 and above on the IC-970H 's 2m
downlink receiver. Similarly, stations using
2m on the uplink (for Mode J) and running
about 25 watts or more, resulted in downlink
signals in the range of S-4 to S-5. Stations
using near 75 watts and up were producing
S-9+ signals. Please note that your signals
may vary due to the gain of your antennas and
loss in your transmission line, and the current
squint angle of the satellite's antennas. In
general, though, the results were very much
on a par with other satellite receiver systems
that I have used in the past.
For transmitting, the 30 and 35 watts produced
by the IC-970's 70cm and 2m transmitters
resulted in below average signal levels
when compared to many of the other downlink
signals on the satellite. To increase my signal,
I decided to activate the speech compressor.
The speech compressor produced a very noticeable
increase in signal strength and improved
the basic sound quality. I estimate the gain
increase was almost 6 dB (one ICOM S-unit).
particular stored memory channel, is also
available with the two remaining positions of
the SATELLITE switch.
Scanning
The main and sub scanning features are not
necessarily needed for satellite operations,
but they are good for local activity. The feature
I liked best is that both the main and sub bands
can be selected for scanning at the same time
(by using the Main and Sub Scan Switches] in
addition to the more common individual band
scan feature found on most receivers.
Both the main and subbands can have 99
memory channels programmed, and they
each have the capability to have a selected
portion of their bandwidth scanned (this feature
uses the P1 and P2 memory Channels).
The IC-970H can perform four types of scanning:
programmed scan, which scans between
two programmed scan edges; memory
scan, which repeatedly scans all memory
channels in the selected band; mode-select
memory scan, which repeatedly scans memory
channels with the same selected operating
mode in a particular band; and multiband
memory scan, which allows scanning with an
optional installed band.
Satellite Packet Operation
In addition to using the IC-970H for voice
communications, 1 used the radio to copy
telemetry from FQ-20, DOVE, and Pacsal.
Currently, I am using a PAC-eOMM Tiny-2
and PSK-1 to decode the SPSK and AFSK
telemetry signals from these birds with my
IC-275H and IC-475H radios. To copy the
telemetry using the IC-970H, I just inserted a
microphone connector and connected the audio
input and ground of the PSK-1 or Tiny-2
(depending upon which bird I was copying
from) to the microphone connector. This provided
the bare minimum connections required
to perform telemetry reception. For DOVE
(AFSK FM), I just tuned to 145.825 and let the
bird pass over. (Here, I did not need to tune for
Doppler.)
However, for the FO-20 and Pacsat satellites
(BPSK SSB), I needed to manually tune
for the correct Doppler-shifted signal. This
1200 MHz Option
The IC-970H comes with 2m and 70cm
band units installed trom the factory . These
two bands are primarily used for Mode Band J
satellite communications. In case you want to
operate on Mode l (1296 MHz uplink and
70cm downlink), the IC-970H lets you install
the UX-97 1200 MHz optional band unit for
Mode l use. The UX-97 supports SSB, plus
CW and FM, and has 10 watts output power.
Satellite Tracking and Memories
In addition to allowing you to store 99 different
frequencies into the per band memory
channels, the IC-970H allows you to store 10
uplink/downlink frequencies and mode pairs
(transponder uplink and downlink tracking frequencies).
I found this feature to be very convenient.
I programmed frequencies for AO­
13's Mode B into cnenner t. AO-13's Mode J
into channel 2, and FQ-20's Mode J frequencies
into channel 3. (To program into a particular
channel, the SAT£LLITE switch must be in
the SATL position.) Now when I need to use a
particular mode on one of these satellites, I
put the SATELLITE switch to the SATL position,
enabling the 10 special memory channels;
then I select a particular channel with the
Memory Channel Switch, and turn the Satellite
Switch to the corresponding tracking direction
(either N or A position). Tuning with the
main dial now changes the main and sub frequencies
in either the same direction or inverse
direction, accordingly.
How did I compensate for the Doppler shift?
When operating in this manner and encountering
Doppler shift, just deactivate the MAINI
SUB switch, allowing frequency changes on
both the main and sub VFOs at the same time.
Change the AX frequency just enough to allow
for the Doppler shift. After this tuning, activating
the MAIN/SUB switch allows you to continue
to change frequencies on both the main and
sub VFOs at the same time by using the main
dial.
Tracking in this manner, but not using a
38 73AmateurRadio Today. March,1991
Frequency coverage
Tuning step increment
Operation modes
Power requirements
Antenna impedance
Current drain (2m)
Usable temperature
Frequency stability
Dimensions
Weight
Output power
Modulation system
Spurious emissions
Carrier suppression
Unwanted sideband
Microphone impedance
Sensitivity
Squelch sensitivity
Selectivity
Audio output power
AIT variable range
Notch filter range
Notch filter attenuation
Specifications
140.1-150.0MHz
430.0-450.0 MHz
1200 MHz Band (with optional UX·97 unit)
50-900 MHz (with optional UX-A96 unit, AX only)
SSB, CW 10 Hz
FM
5,10,12.5,20, 25,0r1oo kHz
All modes 1 kHz and 1 MHz
SSB (A3J), FM (F3), and CW (A1)
13.8 VDC ±15%
500 unbalanced
16A on transmit
2.5A on receive
- 10 degrees C to 60 degrees C
± 3 ppm
425Wx149Hx406Dmm
15.0 kg (without internal power supply)
17.3 kg (with power supply)
5-35W (2m SSB and CW)
6-45W (2m FM)
5-30W (70cm SSB and CW)
6-40W (70cm FM)
s iow (23cm SSB, CW, and FM)
SSB balanced modulation
FM variable reactance frequency modulation
more than 60 dB below peak output power
more than 40 dB below peak output power
more than 40 dB below peak output power
6000
SSB and CW
FM
SSB and CW
FM
SSB and CW
CW narrow
FM
25dB
Table 1. The IC-970H's specifica trons.