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Old 4th Dec 2019, 10:46 pm   #1
carlos10
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Default Kenwood TS120V

hi,
have no rf power output on the 29.500 band segment,
all other bands are fine 15watt.
there is a cw filter yk88c recently installed
any comment welcome
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Old 5th Dec 2019, 12:30 am   #2
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Default Re: kenwood ts120v

Does it receive in that band segment?

I think this radio uses a bank of quartz crystals, the one for that segment may be faulty or e ven not fitted.

David
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Old 5th Dec 2019, 9:42 am   #3
Jon_G4MDC
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Default Re: kenwood ts120v

18,21 and 28MHz share a PLL VCO in freq gen.
It could be this PLL just can't manage to lock any more at the top end.

There is a PLL unlock signal that could be measured though as David says another indication would be if there is also no RX up there either.
Manual says PLL unlock will blank the display - I suppose that you would have noticed that already so maybe it debunks that theory.
I have TS130V and it does state that there are PLL differences - maybe this is one of them?

TS120 manual now obtained and although the PLL works in a different way the display blanking advice is still good.

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Old 5th Dec 2019, 10:08 am   #4
carlos10
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Default Re: kenwood ts120v

hi, thanks reply
it receives on all bands nicely with signal generator, but very weak on 29.5 the last band segment, i suspect there is something out of alignment for that band, it seems there will no drive power to feed the finals on that freqency, all other bands are full power,
can the cw filter be the cause for no drive power for this bandsegment, its a 500hz yk88c
carlos on6cn
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Old 5th Dec 2019, 10:11 am   #5
Jon_G4MDC
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Default Re: kenwood ts120v

No not related to the CW filter.

Good info that RX is weak on that band too. Now we know where to be looking.

Alignment or some issue with a switch is very likely. Sadly the TS120 manual I downloaded has no schematic of RF Unit which is where this
issue will almost certainly be - pages are missing from the scan. It has PCB layout only.

I can put up the equivalent from TS130V - brb.

The thing I had forgotten is that it uses a physical switch not diodes. You can see the 28MHz section is common for 28,28.5,29 and 29.5
Your issue almost has to be a dirty switch contact on 29.5MHz position! On RX you could try poking the contact at each end of the filter with a toothpick.
It will probably break into life for light pressure applied at one end or the other.
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Old 5th Dec 2019, 11:35 am   #6
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Default Re: Kenwood TS120V

THANKS JON
I see only two switches here,bandswitch and mode switch,
So i think you mean band switch.,now poking at each end of the filter,what filter wood that be....
Carlos on6cn
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Old 5th Dec 2019, 11:53 am   #7
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Default Re: Kenwood TS120V

On the bandswitch, the two wafers which connect to RF Unit, when set to 29.5MHz position, I hope you can see the contacts in use.
One is the input and the other is output of the bandpass filter.

The filter is likely to be fine since 28-29MHz bands work OK. I think one of these contacts is bad on the 29.5MHz position. Some pressure on one or the other will probably allow contact to be made. That end is the one needing switch cleaner or further attention.

Good luck. Sorry I have no pictures that would help. I can take some but that would need time.
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Old 5th Dec 2019, 12:33 pm   #8
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Default Re: Kenwood TS120V

got it, broken contact on the second wafer seen from front,
its te contact were the rotor contact blade makes contact,
see if can find such a contact , its rivetted, so securing on the wafer wil be difficult, a lot of thinking for a solution hi
full power when i make contact wth screwwdriver hi
carlos on6cn
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Old 5th Dec 2019, 1:53 pm   #9
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Default Re: Kenwood TS120V

fixed, manage to solder a small lip to the broken contact
thanks to all who replied!
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Old 5th Dec 2019, 8:28 pm   #10
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Default Re: Kenwood TS120V

Thats good news and well done.

It will probably last a long time since how often will 29.5 and higher be used on an SSB rig?

By the way if your fluorescent display has some segments lighting brighter than others (as mine did) suspect the two 1S1555 diodes associated with decimal point (dp) pin.
Mine were leaky and they caused all sorts of odd crosstalk in the multiplexing.

You have made me want to go and dig it out again. Not been on for some years HI HI.

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Old 5th Dec 2019, 9:43 pm   #11
carlos10
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Default Re: Kenwood TS120V

hi, ok
it is a very good trx, simpel and handy, a full 10 watts output, sometimes 15 watt, despite the not so flattering comments that its had a deaf receiver, this is definitly not the case, why on earth should the kenwood engineering staff want to make a deaf receiver hihi, and yes if something is broken i want it fixed,
glad to hear you renewed interest in the rig, its worth it, i make a note of your remarks about the display, have a nice weekend to come, if you have tips, please mail them to me, greatly ap. riciated
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