TS-2000 IF Filter Change

Discussion in 'Radio Circuits, Repair & Performance' started by AA7BQ, Sep 12, 2004.

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  1. AA7BQ

    AA7BQ QRZ Founder Administrator QRZ Page

    I replaced XF-6 IF filter with a International Radio #92 filter. This
    filter is for the TS-50 transceiver originally and is an eight pole 2.1
    Khz. unit.
    Began by removing the bottom cover of transceiver and then remove the
    seventeen screws which hold down the rf circuit board. Also remove the
    heat sink clip from IC9. There is no insulating washer here. XF-6
    filter is chrome plated and is clearly labelled. Unplug one rf cable
    near back of board and mark where it was as there is another unused
    connector nearby. Flip board over and using a small isolated tip
    soldering iron and solder braid clean solder from XF-6 terminals ( 4 )
    and two mounting ears then gently remove it. Using small coax ( I found
    some .045 teflon ) International Radio supplies RG-174, tie the new
    filter in and it can be mounted by the fan area or in my case with no
    voice chip I stuck it in place with the provided double sided tape.
    Since the original filter is coupled through .01 micro farad caps none
    are not required at the filter. The only other thing I did was peak up
    the IF section by peaking L69, L87, L71, L613 and L614. All of these
    inductors are clearly labelled on the circuit board. I did this by
    injecting a weak hf signal and peaking for max output using an
    oscilloscope across the audio leads. Before adjusting these inductors
    remember what position the tool was in when you started. I obtained some
    good peaks on all adjustments. One could also use an ac millivolt meter
    across the speaker leads. Turn up the audio to get a good scope or meter
    reading. Do not peak any other inductors on the circuit board. Using
    the adjustment software one could enter a menu and peak the filter
    centring. I found this to be unnecessary and on the air results while
    switching side bands were " Excellent Kenwood audio".
    I am very pleased with the results of the replacement filter. For
    those who said the radio suffers filter blow bye this is an excellent
    mod and does not deter from the excellent receive or transmit audio this
    radio has. The peaking of the IF section also helped bring up the
    received signal level. My Kenwood filter is at International Radio for
    sweep tests and I'll publish the results on this mod site. Wilbur,
    wilby@epix.net has an operating and service manual for this radio on CD
    for an excellent price and its printable. Charlie W5VIN

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