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Are the "DIY" TSU-8 lookalikes any good?

Discussion in 'VHF/UHF - 50Mhz and Beyond' started by K1FFX, Nov 24, 2015.

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  1. K1FFX

    K1FFX Ham Member QRZ Page

    After a number of years offline, my Kenwood TM-255A is back online. I'd like to add the TSU-8 CTCSS tone decoder to it. Looks like real Kenwood units are very hard to come by, but I see a number of eBay vendors selling Chinese "DIY" (that's how they are described on eBay) versions of the TSU-8.

    Does anyone have any experience with these DIY units? Do they work to spec and are they reliable?

    And if anyone knows of a Kenwood TSU-8 looking for a new home, I'd love to hear about it!

    Thanks -

    Bruce K1FFX
  2. W9GB

    W9GB Ham Member QRZ Page

    Kenwood TM-255A : 144 MHz VHF All-Mode transceiver (Universal Radio Information Page)
    Kenwood TM-255A Owner Manual (Page 52 covers proper installation steps of TSU-8)
    Page 40 of the TM-255A manual covers the proper setup (menus) for CTCSS operation.

    The Kenwood TSU-8 optional accessory (CTCSS function) was only manufactured during the production runs of these radios: TM-461, TM-271, TH-22A, TM-255A, TM-733A, etc.
    Some North American Kenwood dealers still have the TSU-8 option "in stock".

    HamCity (Culver City, CA) sells the Kenwood TSU-8 board (states as Kenwood source).
    USPS Priority Shipping from California will be faster than China Post shipping and customs clearances which can be 3-4 weeks (average during Christmas Holidays) from China (eBay sources).
    Last edited: Nov 24, 2015
  3. K1FFX

    K1FFX Ham Member QRZ Page

    Thanks for all the info! Since the rig needed a new backup battery, I had it open the other day
    and installed a battery clip for the CR-2032, and saw the slot for the TSU-8 which is right next
    to where the battery lives. I have the original owners manual, and the directions for getting
    in there are quite good. [I also did the "TM-255A won't power on after DC power is turned
    off and on" mod, replacing C6 ... that was a good fix, and the problem went away.]

    I'm surprised to see anyone selling a new Kenwood board, but I will follow up with HamCity.
    Thanks a lot fo the pointer.

    - Bruce K1FFX
  4. W9GB

    W9GB Ham Member QRZ Page

    Bruce -

    Kenwood used the Sanyo CR-2032 Solder Tab battery -- same battery used in MILLIONS
    of Toll Road transponders from Chicago (I-90) through Great Lakes states (I-90/I-76)
    to NorthWest USA.
    Panasonic bought out Sanyo -- owning the Lithium coin cell market (70% market share).
    They changed the earlier Sanyo 1F2 suffix, for this specific solder tab specification used by Kenwood.

    Panasonic CR-2032/F2N (solder tab) -- $1.11 part in quantity 1, buy 100 it drops to 77 cents.
    Last edited: Nov 24, 2015
  5. K1FFX

    K1FFX Ham Member QRZ Page

    Yep. That looks pretty much like what I removed. I had received some feedback on
    soldering in a new battery vs. soldering in a clip (possibility of blowing up the battery,
    and needing too much heat to solder). In retrospect, I don't think I would have had
    any problem in installing a new battery, but opted for installing the clip anyway. If
    I still have the TM255-A in 5 years or so, battery replacement will be simplfied.

    I just wrote to HamCity trying to verify that their TSU-8 is a "genuine" Kenwood part.

    Best -

    Bruce K1FFX
  6. K1FFX

    K1FFX Ham Member QRZ Page

    Just to wrap this up ... HamCity does indeed sell the Kenwood TSU-8. I don't know if this
    is something Kenwood is still producing or if HamCity has a supply of NOS. In any case,
    HamCity shipped it 1st Class USPS the same day, and the TSU-8 is now installed and
    functional in my TM-255A. Thanks to W9GB for the pointer.

    - Bruce K1FFX
  7. W9GB

    W9GB Ham Member QRZ Page

    Bruce -

    Great ! Happy to hear you have the TSU-8 part installed and working.
  8. K4JF

    K4JF Ham Member QRZ Page

    On another tack....I sold a TH-42 (poor functioning) and discovered too late that it had the TSU-8 installed. (I should have realized that, as most 70cm repeaters have tone.) So, I now have a TH-22 and I don't know if it has the TSU-8 installed. Don't need it here, but considering a move. So....any way to see if it has the TSU-8 without taking it apart??

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