Kenwood TH-D74A for satellite work?

Discussion in 'Satellite and Space Communications' started by WD9EWK, Oct 6, 2016.

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  1. WD9EWK

    WD9EWK Ham Member QRZ Page

    Last week, I bought a Kenwood TH-D74A when it became available at the Phoenix HRO store. I sent out a quick tweet about this purchase on my @WD9EWK Twitter feed:

    tweet1.jpg


    After fully charging the battery, which took about two hours after this picture was tweeted, I tried to make this HT operate cross-band full-duplex. That is, listening on one band while simultaneously transmitting on another band. Unfortunately, I could not make this radio operate in that manner. Whenever I transmitted from one VFO (Kenwood calls it a "band"), the other VFO is muted until I unkey the PTT. Seeing this, I didn't need to wait to try the radio on a satellite pass to try this out. I sent out another tweet that evening:

    tweet2.jpg

    I also posted a recommendation for those who are interested in purchasing a single HT for full-duplex operation on all FM satellites:

    tweet3.jpg

    The retail price of the TH-D72A had dropped below $400 recently, the lowest it has been since its late 2010 release. The TH-D72A lacks the 222 MHz band , D-Star, and the all-mode receiver found in the TH-D74A, but is still a good radio for satellite work (FM and packet/APRS).

    The inability of the TH-D74A to work FM satellites full-duplex is unfortunate, but not a surprise. I read reports from the Dayton Hamvention earlier this year, claiming that Kenwood representatives were saying this radio (without the TH-D74 model number at that time) would be capable of cross-band full-duplex operation. As this radio gained the TH-D74 model number, and especially after the radio was shown at the Tokyo Ham Fair a few weeks ago, the chatter changed to indicate this radio would not be capable of cross-band full-duplex operation for the FM satellites.

    Even though this radio is not capable of cross-band full-duplex operation, it can be used to work FM satellites. Memory channels in the TH-D74A are similar to those in the TH-D72A and many Icom HTs - memory channels cannot hold transmit and receive frequencies in different bands. This means we must use the two VFOs and switch between them, operating half-duplex. I have used my TH-D74A to make QSOs on all 3 of our current FM satellites (AO-85, SO-50, LilacSat-2) in the past week. Reports on my transmitted audio were good, although using narrow FM on AO-85 appear to indicate audio is very low in that mode. For other AO-85 passes, as well as SO-50 and LilacSat-2, I used "normal" FM.

    Beyond using the HT on FM satellites, I have used the TH-D74A's all-mode receiver as half of my station for working SSB satellites. The first test I did of this was last Friday (30 September) evening on AO-73. Here is a twieet I sent out after that pass, showing my station:

    tweet4.jpg


    Transmitting with an FT-817ND, receiving with the TH-D74A, both connected through a diplexer to my Elk handheld 2m/70cm log periodic antenna. The TH-D74A did a nice job. Its all-mode receiver is a big improvement over the all-mode receiver in the Kenwood TH-F6A, has slightly smaller tuning steps (20 Hz) compared to the TH-F6A (33 Hz), and I was able to use the TH-D74A's audio recorder to capture what I heard. I worked 3 stations on this evening pass - NP4JV in southern Arizona, KG7NXH in Las Vegas, and N1VF in San Francisco.

    Since that AO-73 pass, I have used the FT-817ND/TH-D74A combination on a few other non-FM satellites (FO-29, XW-2A, XW-2F). Just like with AO-73, the TH-D74A's all-mode receiver was up to the task. It has better sensitivity and selectivity than the TH-F6A's receiver. I still prefer the smooth VFO knob on an FT-817 over the tuning knob on the TH-D74A, but I can certainly consider the TH-D74A one of 3 viable options for a satellite downlink receiver when I am in the field (the others being a second FT-817ND, and an SDR receiver like a FUNcube Dongle Pro+ or SDRplay).

    For an FO-29 pass last Sunday (2 October) afternoon, I had a nice treat. I worked XE1H in central Mexico, NH6Y in Hawaii, and N6NUG in San Diego from my driveway with the FT-817ND/TH-D74A combination. It was fun to have NH6Y call me, and the TH-D74A had no problem hearing the satellite:

    tweet5.jpg


    During the last weekend, I also used the HT to work the ISS packet/APRS digipeater on 145.825 MHz. The APRS setup on the TH-D74A is similar to the TH-D72A, so I didn't need to read through the manual much. I was able to define a new packet path ARISS for use with the spaceborne digipeaters (ISS and NO-84), put some text in the comment field that is transmitted with my position beacons, and figured out how to use the messaging functions. With that, I began to work some passes. I have made several QSOs over the past week, and I have been happy with the performance in this mode.

    Last night (Wednesday, 5 October), I was on a western ISS pass with 3 other stations. I made QSOs with two of them - K6VUG in northern California, and KK6OTJ in southern California. One nice enhancement in the TH-D74A over the TH-D72A is that I can see my own call sign in the stations heard list. The TH-D72A would not list my own call sign in the heard listing, even if it heard one of my packets retransmitted by a digipeater. I sent out a tweet after last night's ISS pass with my own form of a stations-heard list:

    tweet7.jpg


    I have tried this HT on all 3 bands it transmits on (2m, 222 MHz, 70cm), and with a local D-Star repeater. Those work fine. I installed a microSD card, and have made several recordings of some of the satellite passes I've worked. The recording function will record audio from one of the VFOs, so I made sure the VFO used for receiving was set as the "recording band" before the pass. The TH-D74A has a micro-USB connector, and Kenwood provides a free USB driver for Windows systems and programs to configure the radio and use its IF output function.

    When I bought my TH-D74A last week, it came with v1.02 firmware. On 30 September, Kenwood released the v1.03 firmware. I applied that last night, and the radio appears to work the same as it did with the v1.02 firmware. I used the programming software (MCP-D74) to copy my radio's configuration before applying the firmware update, as the last step of the firmware update requires a full reset of the radio. I uploaded my previous configuration to the radio after the firmware update, and the radio works fine.

    Similar to the TH-D72A, users can upload a different image that is displayed as the radio is powered on, after the Kenwood logo appears on the screen. After updating the firmware, I took a moment to take one of my images of my two call signs on license plates, and adapted it to fit on the TH-D74A's screen (240x180, 24-bit BMP file). It only shows up for a second or so, but it is one way I can identify my radio from a group of TH-D74As...

    THD74A_with_custom_opening_screen.jpg


    Overall, I like this radio. Here is how I summarized that, in two tweets from Monday (3 October) afternoon...

    tweet6.jpg

    It is expensive at $649, especially when compared to the prices of some of the Chinese-made dual- and tri-band HTs on the US amateur radio market. Then again, if you purchased HTs that contained the functionality of this radio, the $649 price really isn't bad. Using current prices at Ham Radio Outlet for this comparison...

    Kenwood TH-D72A (dual-bander with packet/APRS, GPS): $389.95
    Kenwood TH-F6A (tri-bander with all-mode receiver): $269.95

    These two radios alone are about $10 more than the price of the TH-D74A, and the TH-D74A improves on the all-mode receiver found in the 15-year-old TH-F6A, but then there's D-Star. In my opinion, the closest equivalent to the TH-D74A for D-Star functionality would be Icom's ID-51A. There are a couple of variants of this radio currently on the market: ID-51A at $299.95, or the ID-51A Plus at $364.95. Either of these ID-51A models, added to the price of the two Kenwood HTs above, means you could end up spending around $1000 in HTs to get the functionality found in the TH-D74A.

    As I tweeted, I like this radio. It's a keeper. I wish it could be used to work FM satellites full-duplex, but it has more than enough functionality in it to be useful. Maybe the price will drop, once this radio has been on the market for a while. The TH-D72A debuted around $500 when it came on the market in late 2010, and it was a couple of years before its price dropped to $449, and only in the past couple of months its price dropped below $400. In other words, I wouldn't hold my breath for a big drop in the TH-D74A's price any time soon. If it is a radio you like, save your pennies/centavos/kopecks and get one.

    73!
     
    K4EI, K4BAD, W5SAT and 1 other person like this.
  2. W5PFG

    W5PFG Premium Subscriber QRZ Page

    Nice job, Patrick. It appears you did some thorough testing. For satellite use, it clearly can perform the job of a receiver on both FM and SSB.

    I'm not particular happy with Kenwood for omitting full-duplex capability in this new model. The nomenclature for "TH-D7x" may lead some people to incorrectly assume it is a successor to the TH-D7A(g) and TH-D72A family with inherited full-duplex capabilities.
     
    WD9EWK likes this.
  3. WD9EWK

    WD9EWK Ham Member QRZ Page

    Thanks!

    I still plan to write something for the AMSAT Journal and the AMSAT-BB mailing list, but wanted to have something here along with the images I posted above. I also have the audio recordings to post on Dropbox or some other place, to be done shortly. The TH-D74A certainly can receive FM and SSB satellites, and with some work it can be used to work FM and packet/APRS satellites.
    .
    I agree.

    With 3 bands and the inability to work cross-band full-duplex, the TH-D74A functions more like the TH-F6A (or TH-F7E without the 222 MHz band, for those outside the Americas). Maybe Kenwood wanted to keep the TH-D7x model numbering going with this radio due to the packet/APRS functionality, since all of its packet-capable HTs and VHF/UHF FM mobile radios have TH-Dxxxx or TM-Dxxxx model numbers.

    73!
     
  4. WD9EWK

    WD9EWK Ham Member QRZ Page

    One more comment...

    In the photo of my TH-D74A with the two license plates on the screen, there is a BNC connector on the radio. After briefly using the duckie antenna supplied by Kenwood with this radio to satisfy myself that I could transmt on the 222 MHz band, I put a Diamond BNCJ-SMAP adapter on the TH-D74A's SMA connector. This lets me use all of the antennas and coax I have for my satellite operating, which all have BNC connectors. As with my TH-D72A and TH-F6A, the TH-D74A almost looks like it came from the factory with a BNC connector when you see this adapter on the HT. These adapters have a lower profile on the HTs than the traditional two-piece adapters, even those that have large rubber bushings around the outside of the adapter.

    73!
     
  5. WD9EWK

    WD9EWK Ham Member QRZ Page

    Hi again!

    I have started to post some files related to my TH-D74A and the testing I have done over the past week in my Dropbox space. Go to http://dropbox.wd9ewk.net/ and look in the folder "TH-D74A". I have posted the WAV files recorded by the TH-D74A on the FM and SSB satellite passes I've worked so far, along with a PDF file that has the settings I downloaded from the radio last night, after updating the firmware to v1.03 and uploading my customized BMP file. I removed my call signs from the PDF file, and also removed the D-Star repeater listing. The repeater listing made up 90% of that file originally.

    73!
     
  6. W5SAT

    W5SAT Subscriber QRZ Page

    Wow! Nice report. Now THAT'S how to do a radio report. I am very curious about something. I read somewhere about the '74 having an 12 Khz IF Output via USB port... Can you elaborate on what that is if you know and if you have played with that functionality.

    Not to hijack but I bought a TYT UV8000E this week - it kinda sucks. :)
     
    WD9EWK likes this.
  7. W5PFG

    W5PFG Premium Subscriber QRZ Page

    But is it full duplex?
     
  8. W5SAT

    W5SAT Subscriber QRZ Page

    Nope. Not even close. Just something to bang around when off-roading/ATV riding. Seems solid though.

    Sold my KG-UV8D to a new ham friend.... Screen scratched too easily in the rough environments. Lots of dust ingest. The TYT is the replacement.

    Back to your regular scheduled programming... :)
     
  9. WD9EWK

    WD9EWK Ham Member QRZ Page

    Thanks!

    I was quick to use Twitter to post what I saw in the TH-D74A, and also wanting to confirm some of what had been circulating about this radio. I have worked with some functions more than others in that radio, since I'm more interested in how it works related to working satellites than terrestrial voice repeaters.

    The IF output appears to be similar to the IF output from an HF transceiver. It requires both a USB connection for the ARFC-D74 software to control the frequency and an audio patch cable from the TH-D74A's speaker jack to sent that output to the computer. I have not tried it yet, since none of my tablets have a microphone jack I can connect to. My laptop does, and I'll give this a try over the weekend to see how it works. I am hoping I can feed that output into the laptop and run something like HDSDR to decode what is coming from the radio, like a panadapter.

    73!
     
  10. N8HM

    N8HM Premium Subscriber QRZ Page

    Don't all of your Windows tablets have a standard TRRS mic/headphone connector? I'm pretty sure all of mine do.

    If not, a $2 USB sound dongle would work.
     

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