1. Time for some upgrades in server hardware and software to enhance security and take AK to the next level. Please contribute what you can to sales@audiokarma.org at PayPal.com - Thanks from the AK Team
    Dismiss Notice

Kenwood Trio 600T IF display

Discussion in 'Tuners' started by steveUK, Nov 15, 2018.

  1. Bob@FM

    Bob@FM Active Member

    Messages:
    367
    Location:
    NE NY
    Others have also frequently commented on the TX-9800 as one of the best stock tuners for DX reception, so this is not surprising to me.

    When you start splitting hairs for DX reception, the IF filter bandwidth makes a huge difference, the more narrow, usually the better the reception. The stock 600T filters are fairly wide, even in the most narrow setting. They just added more 280 kHz filters in series to make the "narrow" filter. These are the old 4 pin double filters, but easily replaced with 2 typical 3 pin types (per each 4 pin) and sockets. You connect the 3rd pin of filter one to 1st pin of filter two on the socket, and cut the socket leads for those 2 (there are no holes on the tuner circuit board for those middle pins).
     

     

    Please register to disable this ad.

  2. steveUK

    steveUK AK Subscriber Subscriber

    Messages:
    507
    Location:
    Midlands, UK.
    Thanks for that Bob, interesting for sure. Are there any more detailed instructions anywhere for doing this? What parts to buy, which ones to change, layout etc?
     
  3. Bob@FM

    Bob@FM Active Member

    Messages:
    367
    Location:
    NE NY
    I never wrote it up, but it is fairly obvious once inside. Here's some links on filters and how to replace. Getting filters is like buying FM antennas today. The 3 pin version are no longer in production (only surface mount now) but large stocks exist at some distributors.

    http://www.fmtunerinfo.com/filters.html

    http://home.computer.net/~pritch/betterfm.htm

    this last one is a defunct site, retrieved with the help of "the wayback machine"
    https://web.archive.org/web/20040811101202/http://pages.cthome.net/fmdx/filter.html
     
  4. steveUK

    steveUK AK Subscriber Subscriber

    Messages:
    507
    Location:
    Midlands, UK.
    Thanks Bob, very helpful.
     
  5. rcs16

    rcs16 Super Member

    Messages:
    4,067
    Location:
    Baldwin, Ontario, Canada
    I agree the 600T and my KT-8300 needs another filter setting, like the T-85, using at least a couple of selected 180Khz filters strung together. I got the last 3-pins ones from Mouser. I guess in the old days the FM band was not as packed, channels were far apart, no need for very narrow filters.
    Maybe if I get energetic, I could make a small pcb and use the smt versions to adapt to the old 4 pin doubles.
    I have a SX-1980 on the bench it has 5 blue Murata filters and HA1201 IF amps between each of them, it still has problems with my low power favourite station. I noticed this tuner has some very detectable IF images., similar to the KT-8300, to much RF amp, overloading the mosfet mixer I believe, your 600T has a double balanced mixer (DBM), so it should do much better with RF overload and IMD.
     
    Last edited: Dec 7, 2018
  6. steveUK

    steveUK AK Subscriber Subscriber

    Messages:
    507
    Location:
    Midlands, UK.
    Thanks. Doesn't the Pioneer TX-9800 and SX-1980 share a certain amount of RF design technology? Not saying they're the same but both use a similar 'auto-lock' system.
     

     

    Please register to disable this ad.

  7. rcs16

    rcs16 Super Member

    Messages:
    4,067
    Location:
    Baldwin, Ontario, Canada
    Similar, but slightly different as well. The SX-1980 I believe uses a 3rd party RF FE that is similar or the same as a Rotel model.
     
  8. Punker X

    Punker X Moderator Moderator Subscriber

    Messages:
    4,018
    Location:
    Panic in Detroit
    Also used in the Sansui TU-919.
     
  9. rcs16

    rcs16 Super Member

    Messages:
    4,067
    Location:
    Baldwin, Ontario, Canada
    I thought the RF FE in the SX-1250 worked better, Did not seem to over load as much, even though it has no gate 2 AGC.
    Also the SX-1980 tuner has fixed tuned coils, they want you to mess with the outside fins to do the low end tune tuning. They could have said you can also play with the coil spacings too.
    Starting to hate old mechanical tuners, varactors all the way :)
     

Share This Page