ICOM IC-910H VHF/UHF Multimode Transceiver
Reviewed by Steve Ford, WB8IMY
The ICOM IC-910H offers a great selection of capabilities and features for the VHF/UHF enthusiast. Its multiple modes and ample power output— and optional 23-cm coverage—make it a versatile tool for FM, weak-signal terrestrial and satellite operation.
It's easy to pigeonhole the IC-910H as a "satellite transceiver," but that would be a mistake. This radio offers a range of versatility—not to mention a hefty 100 W output on 2 meters and 75 W output on 70 centimeters—that makes it a truly multipurpose rig.
The IC-910H is disarmingly compact at only 91/2 x 311/16 x 913/32 inches. Despite its size, all of the front-panel controls and switches are ergonomically placed for effortless operation (even with big fingers like mine). The VFO knob is large and its rotation is smooth. The expansive LCD display is easy on the eyes and readable from every angle. Since the IC-910H is a dual-band radio (actually, it's triband if you purchase the 1296 MHz module), you have separate RF/AF gain and squelch controls on the front panel. The microphone and headphone jacks are on the front panel as well. (A small hand mike is included.)
Turn the radio around and you find antenna jacks for 2 meters and 70 centimeters (installing the optional UX-910 1296-MHz module adds a third antenna jack). There are three accessory sockets, two data jacks for digital communication, a pair of external speaker jacks, the obligatory dc power connector and an interface jack for computer control. All in all, it is a clean, uncomplicated layout.
The IC-910H as Terrestrial SSB/CW Transceiver
The IC-910H is an exceptional tool for exploring the mysteries of the so-called "weak signal" modes. The convenience of being able to jump back and forth between bands is something that could spoil me in a heartbeat. The IC-910H displays both the "main" and "sub" band frequencies vertically (main on top, sub below) along with bargraph-style signal-strength indicators in each section. You can receive simultaneously on both bands, but you can transmit from the main band only (this arrangement is reversed when you are in the satellite mode). Of course, a quick press of the button flips the main/ sub frequency assignments. The '910H has two VFOs for each band. You can opt to use the main VFO knob to make frequency changes on either the main or sub bands—or assign the RIT or IF SHIFT
knobs to function as the sub band VFO control (clever!). You can even punch your chosen frequencies in directly from the front-panel keypad.
I used the '910H primarily to hunt contacts on 2 meters and 70 centimeters. Even with my puny attic-mounted Yagis, the range was impressive. SSB contacts spanning 150 miles were not uncommon on 2 meters. During a brief band opening on 70 centimeters, I enjoyed an SSB contact on 432.1 MHz over a distance of about 100 miles. With outdoor antennas, low-loss coax and receive preamps, I'm confident that my communicating range would have been considerably greater.
On 1296 MHz I set up a couple of skeds with a local station just to see how the IC-910H played on this band. Reports on my transmit signal were very favorable, and the local station that I was communicating with sounded good as well. The overall lack of activity on the band in my area and my less than optimal antenna (a small helical) gave me less success with unscheduled contacts than I had on the other bands.
IC-910H as FM Transceiver
The IC-910H is a fully capable FM transceiver. The considerable output power on 2 meters and 70 centimeters gives the radio a formidable punch on FM simplex. For repeater operation the '910H offers most of the same convenience functions you find on many mobile FM rigs. The duplex offset frequencies are programmable for each band. There is a 50-tone subaudible (CTCSS) tone encoder/decoder for use with repeaters that require the tones for access. The stock microphone, however, does not include a DTMF pad for control or phone patch applications.
Testing the '910H on FM was an ideal opportunity to experiment with the memory and scanning functions (although these functions are available for other modes as well). The IC-910H sports 106 memory channels—99 regular channels, 6 scan-edge channels and one call channel for each band. The memory channels can be programmed with the frequency, mode, simplex or duplex and subaudible tone frequency. Alphanumeric memory naming is not supported.
There's also 5 (or 10—your choice) "Memo Pad" memories. These are very handy for temporarily storing interesting frequencies. This storage system is set up as "first in, first out." When you program in the sixth (or 11th) frequency, the first frequency that you memorized will be erased.
Memory programming is straightforward and probably familiar to most FM operators. You can transfer VFO contents to a memory channel, or vice versa. The call channels are convenient memory slots to store a single frequency (or frequency combination) for each band that you use often. To access one of these, you simply push the MS/BAND button to select the desired band, then press the CALL button.
There are three scanning modes in the IC-910H: memory scan, programmed scan and mode-select scan. The memory scan, as the name suggests, scans through the memory channels, automatically excluding blank, call or scan-edge channels. A "memory channel lockout" feature, for temporarily excluding a specific memory channel from a scan, is not included. The scan resume conditions (what happens after the scan stops on a busy channel) and the scan speeds are selectable. In the programmed scan mode, the '910H scans in the VFO mode between the two frequencies programmed in the scan-edge memory channels. Mode-select scan is intriguing. It allows you to scan through only those memory channels that are programmed with a particular mode (FM, SSB or CW). For example, you can set up the '910H to scan only your SSB "hot spots" if that is your interest at the moment!
I've already mentioned that the IC-910H can generate subaudible tones for repeater access. As it turns out, the tone-scan function allows you to detect these tones as well. If you don't know the frequency of the subaudible tone in use on a particular repeater, the '910H can scan the incoming signal and alert you to the exact tone frequency. In fact, you can configure the transceiver to activate its own tone squelch function. In this mode, the '910H remains silent until the proper subaudible tone is received.
Related to the various scanning functions is the IC-910H's simple band scope. This feature allows you to sweep both sides of a center frequency to check for activity. Detected signals are displayed as part of the signal-strength indicator for each band. This feature is available for SSB as well as FM.
IC-910H as Satellite Transceiver
Despite the versatility of the '910H, its use as a satellite transceiver garners the most attention in the amateur community. Considering the innovative satellite-operating features this rig provides, this is easy to understand. I'd be less than honest if I said that I wasn't eager to try the '910H on the satellites as quickly as possible.
I put the IC-910H to work primarily on the Fuji-OSCAR 29 and 20 satellites because these birds operate in Mode J— listening on 2 meters and retransmitting on 70 centimeters. In addition, both satellites use inverting transponders. Whatever you transmit on the uplink is inverted on the downlink—LSB on the uplink becomes USB on the downlink; a signal at a frequency in the lower portion of the uplink passband appears at the upper portion of the downlink passband. Add the considerable Doppler frequency shift that's present on the 70-cm downlink and you have the potential for serious operator confusion. (A condition that may also exist on the new AO-40 satellite—it uses inverting transponders.) The IC-910H promises features to alleviate the headaches. Does it deliver?
Prior to my first Fuji-OSCAR attempt with the '910H, I set the downlink frequency on the main band at 435.900 MHz—the top end of the downlink passband. I entered the uplink frequency in the sub band at 145.900 MHz, which is the bottom end of the uplink passband. By switching to the satellite mode and enabling reverse tracking, I was ready to go. It's worth noting that the '910H includes 10 separate satellite memories that you can preprogram with all the necessary setup information for your favorite birds.
When OSCAR 20 rose above 10 degrees elevation, I was able to hear the CW beacon clearly with my attic Yagis. I began tuning up through the downlink passband and watched as the '910H's uplink frequency stepped downward automatically in perfect sync. Despite that fact that I wasn't using a receive preamplifer, I was able to eavesdrop on several SSB conversations without difficulty.
A quick phone CQ brought a response and a 59 report. Doppler shift on the 70-cm downlink was tricky, but the IC-910's automatic reverse VFO tracking made it easy to compensate. I didn't have to remind myself to raise my uplink frequency to compensate for Doppler shift on the downlink.
And even with my mediocre antennas, the '910H provided more than enough output for my signal to be heard through the satellite. In fact, I often discovered that I was a little too strong. (The rule of thumb is that your own signal on the downlink should be roughly equal in strength to the satellite's CW beacon.) Thankfully, the '910H's output is adjustable all the way down to 5 W.
Digital satellite enthusiasts will be pleased to hear that ICOM has paid particular attention to data communication in the IC-910H. As you can see in the accompanying ARRL Lab test results, the bit-error-rate (BER) performance of the '910H was impressive. Using a 9600-baud modem and WiSP software, I was able to consistently grab large amounts of data during two KITSAT-OSCAR 25 passes......
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