ICOM IC-970H VHF/UHF Multiband All-Mode Transceiver
A great rig for both satellite and local communications.
Recently I had the opportunity to use an ICOM IC-970H VHF/UHF (i.e., 2m and 70cm) multiband transceiver. This is a full-featured multi-mode rig designed with the satellite operator in mind. It's also a fine rig for terrestrial contacts both on SSB/CW and FM.
Dimensions and Front Panel Layout
The IC-970H is a big radio: 16.7" W x 5.9" H x 16.0" D, approximately the same size as ICOM's IC-765 HF radio,
The front panel of the radio supports "big-ger-the-better" controls. The tuning knob is 2" in diameter, and the basic control knobs are 0.75" in diameter. In the center of the front panel, there is a 4,5" x 2.5r' black-on-yellow LCD display which provides the following information;
- Main and sub mode of operation.
- Main and sub operating frequencies.
- General coverage RX on/off.
- RIT change of frequency (only for main).
- Main and sub VFO (A or B) selection.
- Main and sub memory channels.
- Sub receiver S-meter.
- Tuning pitch indicators.
- Main and sub duplex indicator,
- Scan indicator.
- Tone/squelch/beep indicator.
- Split operation indicator.
Also, the radio has a large S meter, 2.75" x 1.75"» that is placed directly to the left of the LCD display.
On the very left side of the radio, you can find the satellite switch which provides the following six tracking configurations (and which proved to be very useful during my satellite experimentation and operation with the radio):
- OFF Main and sub frequencies do not track.
- N (Normal) Main and sub frequencies change in same direction.
- R (Reverse) Main and sub frequencies change in opposite direction.
- SATL Used for programming uplink and downlink pairs to memory, no tracking takes place.
- SATL-N Allows selection of uplink/downlink memory channel, tracks in same direction.
- SATL-R—Allows selection of uplink/downlink memory channel, tracks in opposite direction.
I'll discuss more about the satellite switch in the ''Satellite Memories1* section.
The manual is 48 pages long The majority of the manual describes what each of the control functions and connections on the front and rear panels do. The remaining sections of the manual provide general operating procedures for packet and satellite operation, and provide details (with many internal views of the radio and replaceable components) about how to install optional accessories and modify factory set internal controls. I was impressed with the level of detail presented in this manual. It is one of the best that \ have seen ICOM produce. See Table 1 for a complete listing of the IC-970H's specifications.
Receiving and Transmitting
During my voice communications. I spent most of my time operating on AO-13. I made QSOs on this satellite for just about three-fourths of the entire pass on two different days. This allowed me to test the IC-970H during various operating conditions, such as when the squint angle of the satellite's antenna was greater than 20 degrees, less than 20 degrees, and on the two major modes used:
Mode B (70cm up and 2m down) and Mode J (2m up and 70cm down).
For antennas, I used the KLM 18C(12.0dBi gain) for 70cm, and an old beat-up Cushcraft 10-element beam (10.5 dBi gain) on 2m. The preamplifiers were the ICOM AG-35 (15 dB gain, NA noise) for 70cm, and the ICOM AG* 25 (15 dB gain, NA noise) for 2m, mounted at the antenna feedpoint. For feedline. I used an 80-foot run of Belden 9913 (2.6 dB loss per 100 feet) for 70cm. and a 50-foot run of RG-8/U foam (2.0 dB loss per 100 feet) for 2 meters.
Most of my AO-13 QSOs were made on Modes B and J. While operating on AO-13. I worked the following stations (all contacts were on Mode B, unless otherwise noted): AA6PJ, KC7IT, DD5LQ, ON1LST, PE1HXD, FC1GNV, PA0STE, OE5WHNt SM2SWU, JA9WMS, UAGOB (both B and J). JR2UOE, and VK4K2R (Mode J only). As you can see, I made contacts with many locations around the world.
In addition, I used my IC-275H and IC-475H during these passes to compare the versatility of the IC-970H's uplink and downlink systems.
The first thing that caught my attention was the IC-970H S audio. Its audio is much more robust (better bass) than what my IC-275H or IC-475H produces Good audio always makes satellite communications more enjoyable.
For receiving, the IC-970H has comparable sensitivity to both the IC-275H and the IC-475H. Most stations running about 25 watts and up on ACM3'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 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).
1200 MHz Option
The IC-970H comes with 2m and 70cm band units installed from the factory. These two bands are primarily used for Mode B and 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 channel 1, AO-13's Mode J into channel 2, and FO-20's Mode J frequencies into channel 3. (To program into a particular channel, the satellite 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 f select a particular channel with the Memory Channel Switch, and turn the Satellite Switch to the corresponding tracking direction (either N or R position). Tuning with the main dial now changes the main and sub frequencies in either the same direction or in* verse direction, accordingly.
How did I compensate for the Doppler shift? When operating in this manner and encountering Doppler shift, just deactivate the MAIN/ SUB switch, allowing frequency changes on both the main and sub VFOs at the same time. Change the RX 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 particular stored memory channel, is also available with the two remaining positions of the SATELLITE SWitCH,
The main and sub scanning features are not necessarily needed for satellite operations, but they are good for local activity. The feature I li ked 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, I used the radio to copy telemetry from FO-20, DOVE, and Pacsat. Currently, I am using a PAC-COMM Tiny-2 and PSK-1 to decode the BPSK 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 tuning is common, and can be eliminated by connecting additional lines from the PSK-1 to the ACC plug on the rear panel of the IC-970H.
The telemetry sent from FO-20, DOVE, and Pacsat did not require the use of a preamp to receive good packets. All passes I experimented with had elevations of about 25 degrees or higher, and telemetry could be decoded for about three-fourths of the entire pass. Signals were on the average of S-5, with peaks in the range of S-9 to S-20 on FO-20 and Pacsat (SSB), and full S9 * 40 on DOVE (FM). During these experiments, my antennas were placed to point directly west and at 0 degrees elevation. Obviously, you can get better signals if you point your antennas directly at the satellite.
On the rear panel of the IC-970H, a TTL-level remote jack is provided for Cl-V converters. This remote jack can also be used to track uplink and downlink frequencies with another radio, such as the IC-1271 or!C-1275 (if you already have one and don't need to buy the optional 1296 MHz module), in conjunction with tCOM's CT-16 satellite interface. This will operate in the manner described above when you are tracking uplink and downlink frequencies in the same or reverse directions.
Pros and Cons
Features I'd like to see:
- SWR meter.
- DTMF keypad.
- A microphone included with rig.
- increased output power comparable with other H models.
- Individually activated preamps.
Features I liked:
- Automatic tracking for uplink and downlinks.
- Separate memory channels for satellites.
- Excellent weak-signal receivers.
- Great audio quality.
- Large frequency dispiay.
- Large multi-function meter.
- Additional S-meter for sub band.
- Large easy-to-handie controls and switches.
- Additional band units can be installed.
It's Worth Buying
Overall, the IC-970H is a great rig for satellite communications and local activity. I found the IC-970H easy to use, and very capable of either voice or data satellite communication modes.
1991 - Joe Hotman KA7LDN - 73 Amateur Radio Today