Kenwood TH-D74A for satellite work?

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

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  1. W7LZN

    W7LZN XML Subscriber QRZ Page

    Love all the details you provide! I have an Elk antenna in the garage, and a TH_D74A on order. Would you be willing to share more on the mods done to the antenna?
  2. WD9EWK

    WD9EWK Ham Member QRZ Page

    The antenna is the Elk 2m/70cm log periodic where the double boom also has the black coating like the other elements. Instead of the PVC used for the handle, Tom WA0POD replaced the PVC with a carbon-fiber tube and non-conductive hardware to mount the handle next to the booms. Not only is the carbon-fiber material lighter than PVC, mounting it closer to the booms makes for a better-balanced antenna when holding it and pointing skyward. Tom asked me to try it out last fall. I liked it, and bought it from him.

    As mentioned very early in this thread, the TH-D74 is not the ideal radio for working FM satellites. You can do it, but it involves going back and forth between the two VFOs, as the memory channels don't allow a receive and transmit frequency in different bands. The older TH-D72 is capable of cross-band full-duplex operation, where you transmit on one band and can simultaneously receive the satellite on the other band, making it better for FM satellite work. I like the screen and different type of keypad compared to the D72, and working APRS through the orbiting packet digipeaters (ISS, NO-84 when available) seems a lot easier to me with the D74. I hope to be able to make some packet QSOs through them during Field Day in a couple of weekends from now.

  3. K5UNX

    K5UNX Ham Member QRZ Page

    I am considering picking up a TH-D72A since I would like to work Sats. I don't care about D-Star. They are under $400 now. Worth it rather than the '74??
  4. K3RLD

    K3RLD Ham Member QRZ Page

    For FM voice, YES! There was one for sale in HI here in the swapmeet for $250 a few weeks ago.... killer deal.
  5. KB2YSI

    KB2YSI Ham Member QRZ Page

    Does anyone happen to know how the audio out socket is wired, mono/stereo? It seems to be mono but hard finding any information on it.

    I am having trouble with the radio doing odd things while I had headphones in while doing satellite passes.
  6. K3RLD

    K3RLD Ham Member QRZ Page

    There are a few people who have documented the weird audio out behavior, but I believe if you plug in everything before powering up the ht, you should be ok.
  7. WD9EWK

    WD9EWK Ham Member QRZ Page

    The 2.5mm socket is a 3-conductor socket, but two of the 3 conductors are supposed to be used together for audio (not the tip, but the other two conductors). I have an adapter going from a stereo 2.5mm plug to a stereo 3.5mm socket, but plug in a mono 3.5mm plug from my splitter. Works fine, as long as I don't plug it in or take it out while powered on.

    The center of the 3 conductors on the 2.5mm plug is used for one of Kenwood's speaker/mics with 3 buttons. Those buttons are used with certain user-defined functions on many Kenwood HTs, going back to (IIRC) the TH-77 in the 90s. When you plug in or unplug something when the radio is powered on, the radio thinks you may be using that speaker/mic's buttons.

    KA2CZU likes this.
  8. WD9EWK

    WD9EWK Ham Member QRZ Page


    In recent times, I took a cheap HP Stream 14 laptop that wouldn't accept the Windows 10 version 1803 update last month, put the Workstation version of Fedora 28 on it, and I am now getting around to trying different things with Linux. This laptop has a 14-inch screen, 4GB RAM, a 32GB internal drive, 3 full-sized USB ports, Bluetooth, 2.4 and 5 GHz WiFi, and a full-sized SD card slot. The CPU is a Celeron N3060, a 64-bit CPU at 1.6 GHz. Other than the larger screen, being able to use a 64-bit OS with the 64-bit CPU (most cheap Windows tablets have 64-bit CPUs, but run a 32-bit OS) and overall size, the internals of this laptop are closer to the cheap Win10 tablets I've used over the past few years. Other than having to be mindful of the small size of the internal drive, this laptop isn't bad for its cheap price.

    One of the things I wanted to try was mounting my TH-D74's microSD card on the laptop via USB. As mentioned early in this thread, I wasn't able to do this, and Greg KO6TH joined in the thread:

    I confirmed the TH-D74 had its USB interface in Mass Storage mode, so I could access the files on the microSD card. When I plugged the cable from the HT into the laptop, the microSD card was automatically mounted, and a file browser window opened. I was able to navigate the filesystem, move the WAV files between the HT and laptop, even play one of the WAV files from the HT. Whatever the bugs were in the past, at least with Fedora 28 they have been addressed.

    I still need to try accessing the microSD card via Bluetooth (and what else I can do that way), and what I can do with the HT's USB interface in the "COM+AF/IF Output" mode. I do not see the TH-D74 listed on the CHIRP home page at , so I will continue using the Kenwood software on one of my Windows PCs to manage the HT's configuration. I may try to get the program running under something like Wine on the Linux laptop, but not right away.

    KA2CZU likes this.
  9. KO6TH

    KO6TH Ham Member QRZ Page

    Hi Patrick,

    Ok, interesting... So, the Fedora 28 distro isn't tripped up by Kenwood's representation of the USB device. I wonder what's changed? I'm on OpenSuSE Leap 42.1, which is several years older. Could you do me a favor and post the bottom set of messages from the 'dmesg' command, to see if there are any diagnostic messages about how it did this? Thanks!

  10. WD9EWK

    WD9EWK Ham Member QRZ Page

    Here goes...


    After the TH-D74 was mounted, I could navigate the filesystem on the card. After that, I unmounted it, and unplugged it from the laptop. The screenshot shows the messages when I plugged it in, through the unmounting.


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