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Icom ID-51A

Discussion in 'Satellite and Space Communications' started by K6LCS, Jul 1, 2014.

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  1. K6LCS

    K6LCS Premium Subscriber QRZ Page

    Has anyone worked or heard of reports of working SO-50 with the Icom ID-51A?
  2. WD9EWK

    WD9EWK Ham Member QRZ Page

    Short answer...

    The ID-51A works like the Kenwood TH-D72A on SO-50, but without the capability of cross-band, full-duplex operation. A very expensive HT for working SO-50, but receives the downlink well.

    Long answer...

    The ID-51A, as with most Icom VHF/UHF FM handheld and mobile radios, has a very good receiver to deal with the weak SO-50 downlink. With the squelch wide open, I had no problems hearing the downlink on different passes. Like with the TH-D72A and almost all other Icom VHF/UHF FM HTs and mobiles made in the past 10-15 years, you cannot program memory channels where the transmit and receive frequencies are in different bands. Icom's memory-channel programming stores the receive frequency and offset for the transmit frequency, but won't let you set the offset size to be around -290.9 MHz. The two VFOs can be used with frequencies in each VFO, or with memory channels programmed with the individual frequencies used for SO-50 (145.850 MHz with 74.4 Hz tone to activate the satellite, 145.850 MHz with 67.0 Hz tone to talk through the satellites, and a series of frequencies between 436.785 and 436.805 MHz for the downlink). The 5 kHz tuning steps in the ID-51A are good for working SO-50, as its receiver doesn't have the sharp filtering like I saw with the Wouxun KG-UV8D (on that radio, using 2.5 kHz tuning steps is necessary to hear the SO-50 downlink throughout the pass).

    The ID-51A, like the TH-D72A I mentioned before, can receive two frequencies at the same time. This means you can keep the 2m transmit frequency as the active ("MAIN") VFO most of the time, and only switch to the other VFO to adjust the 70cm receive frequency. HTs with a single VFO make operators switch between VFOs more often, which can be confusing. For those HTs, there can be times where the operator accidentally transmits on the 70cm downlink frequency, losing track of which VFO is being used for the transmission. I tightened the squelch to the maximum setting (9) on the VFO I used for transmitting, and left the squelch completely open on the VFO I used for receiving. That way, unless someone near me was transmitting on 145.850 MHz, I knew I was hearing the 70cm downlink from SO-50.

    To improve a station using an ID-51A to work SO-50, using a second radio as a transmitter would be an option. Use the nice receiver in the ID-51A, and transmit with another radio to work full-duplex. Even a US$ 30 Baofeng UV-5R could serve as a transmit radio in this case. A diplexer would also be needed if using a log periodic antenna like the Elk 2m/70cm antenna. For dual-band Yagis like the Arrow Yagi and many homebrew designs, or when using different antennas on each band, you could skip the diplexer and just run coax between the two radios and the feedpoints on the antenna. Leaving a diplexer in the coax running to the 70cm radio, and only connecting the 70cm side of the diplexer, is a good filter to only allow the 70cm signals down to the receiver.

    The ID-51A is a nice radio, but very overpriced (currently around US$ 500 in the US) if its primary use is to work satellites. In fact, unless D-Star is something you're interested in, skip the ID-51A and its high price. With the upcoming Fox-1 satellites starting in 2015, being able to work FM satellites full-duplex will be more important. The AMSAT-NA Fox-1 satellites will require operators to adjust their transmit frequency, instead of the receive frequency as is done with SO-50 (and was done on AO-27 and AO-51 in the past), to deal with the Doppler effect. Not being able to hear yourself while transmitting, and knowing when to make those adjustments, will be a problem on those upcoming satellites. Full-duplex operation on SO-50 is also a good thing, even though operators generally make no adjustments on their transmit frequency for that satellite.

  3. W5PFG

    W5PFG Premium Subscriber QRZ Page

    Fine. I'll bite. I purchased and sold an Icom ID-51A right here on I will skip offering my poor opinion of the digital voice capabilities.

    For satellite use, I was not impressed. It is easy to change between the Main and Sub VFO's but it didn't pass the full-duplex test at full power. I didn't give it a thorough evaluation but I would definitely mark it off my list of suggested radios for someone wanting a full-duplex HT. I'd say get a Kenwood TH-D72 if you're hell bent on buying a new full-duplex HT.

    At the cost of two Chicom handhelds, you can do much better for a full-duplex portable satellite station. Even two supermarvelousfantastical Yaesu FT-60R's are a better value.
  4. WD9EWK

    WD9EWK Ham Member QRZ Page

    I borrowed the ID-51A, and only briefly dabbled with the D-Star part of it. The only reason someone should try this HT on SO-50 is if they already own one (or borrow one), and will use it with another radio. It can work half-duplex, which might be OK for SO-50, but will be a handicap for the Fox-1 satellites or any other U/V satellites.

  5. N8HM

    N8HM Premium Subscriber QRZ Page

    I know a local who owns one. If that parrot repeater on TableSat-Aurora works and is turned on over North America sometime, I want to see if I can access it with a DSTAR HT.
  6. W5PFG

    W5PFG Premium Subscriber QRZ Page

    I'm looking for a radio that electrocutes people who repeatedly call you, pass after pass, who have worked you many times over in the log.
  7. N8HM

    N8HM Premium Subscriber QRZ Page

    W5PFG this is November Eight Hotel Mike Fox Mike One Eight
  8. N4UFO

    N4UFO Ham Member QRZ Page

  9. W5PFG

    W5PFG Premium Subscriber QRZ Page

    What is Fox Mike One Eight?

    I thought, according to some, it would be "Franko Mary."
  10. WD9EWK

    WD9EWK Ham Member QRZ Page

    This would be interesting to try, and a reason for me to borrow that ID-51A again. You'd probably need to program a group of memories to deal with the Doppler for the 437.050 MHz frequency published for the D-Star parrot repeater, something like the following:

    1. Uplink 437.040, downlink 437.060
    2. Uplink 437.045, downlink 437.055
    3. 437.050 simplex
    4. Uplink 437.055, downlink 437.045
    5. Uplink 437.060, downlink 437.040

    By the way, there was supposed to be a test of the parrot repeater in the past week. I haven't seen any posts on how that went, not even on the translated form of R4UAB's blog entry about the satellite and test from an article on the AMSAT-UK site.

    One issue that was found with previous D-Star tests on AO-27 in 2007 (scroll down most of the page to see the D-Star test details) was the 5 kHz tuning steps were not great for satellite operating. There would be times that signals would not be decoded, because the apparent frequency fell almost exactly between the frequencies using 5 kHz steps. The earlier AO-27 tests required two radios, because no D-Star radio then - or now - allows for cross-band, full-duplex D-Star operation. The parrot repeater would eliminate the need for the second D-Star radio.

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