AA7BQ
09-11-2004, 11:18 PM
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
Quote[/b] ]Note from AA7BQ:
I posted this on behalf of the author. Please do not contact me regarding this info.
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
Quote[/b] ]Note from AA7BQ:
I posted this on behalf of the author. Please do not contact me regarding this info.