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Kenwood ts440s

Feb 12th 2014, 23:42


Joined: Jan 7th 2014, 15:39
Total Topics: 0
Total Posts: 0
I am having trouble with my TS440s. VCO2 on the PLL won't lock.
re. page 73 service manual
At tp5 I measure 7.8 v and adjusting T9 has no effect. Any ideas as to what componants might be at fault?
Dec 2nd 2017, 17:44


Joined: Nov 15th 2017, 20:41
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Total Posts: 0
I realize this is a 4 year old thread. Were you ever to fix the VCO2 problem? I have my Dad's old TS-440 and have been slowly trying to get it going again. Already fixed the Band Pass Filter diodes and Cleaned the VCO5. Now the next thing to fix is the VCO2. I only have 0.97 vdc on the T9 test point which should be 6.4 vdc. No changed when adjusting the T9 coil. Still looking for the failed component. Thanks to anyone who has an idea. Not much web info on the VCO #2 for this radio.
Dec 3rd 2017, 09:58


Super Moderator

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
Are the VCO parts covered with a potting compound? If so and there is no other obvious component failure it is likely it has gone bad and needs to be removed. But, at 30+ years, all sorts of failures are possible.

Zack Lau W1VT
ARRL Senior Lab Engineer

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