Kenwood TS60

[KC4MOP]

Hello friends
Bought a TS60 from some operator near Haiti and thought I was getting a nice all mode 100W transceiver.
The RF output power may sometimes reach 100W on FM, most of the time it is only 70 watts. Keying and unkeying quickly the power will jump up to 100W. Most of the time it is only 70 watts.
I remember Kenwood has had bad solder connections for the RF transistors and thought I could pull the same repair on the TS60, re-soldering the tabs.
On USB as I make long tests the RF will drop out and come back as I make like I'm calling CQ. But if I make a long audible sound in the mic. (Dummy load, of course) The RF power will stay around 80watts sometimes jumping up to 100 W pep.
Any company repair these radios? I cannot justify any extra money for another radio. I thought this was going to be winner for me.
I would hate to go down the road of trial and error in the output PA section. Those ceramic transistors can get unpredictable at times.
Thanks for any help.

[N4NYY]

Did you try it on a dummy load?

[N5VTU]

Did you try it on a dummy load?

On USB as I make long tests the RF will drop out and come back as I make like I'm calling CQ. But if I make a long audible sound in the mic. (Dummy load, of course) The RF power will stay around 80watts sometimes jumping up to 100 W pep.

[N4NYY]

Damn. I better get my eyes checked again !

[KA4POL]

Good you are using a dummy load. This excludes the antenna and cable. I guess the dummy load is 50 Ohm.
Does your observation happen as well in medium and low power settings? Your power supply is strong enough for the radio?
One issue you might have is grounding of the boards. Many people just consider the voltage going in. If you have grounding problems there is no way back. So loosen the screws a bit and re-tighten them carefully (!).

[KE3WD]

Could be the T/R relay, contact cleaning or replacement. 

Try tapping on the relay with a pencil or spudger while transmitting into dummy load and observing output power.  Should not change with the tapping.


73

[KC4MOP]

Thanks for the replies. Yup, Dummy Load always. The relays are small sealed plastic type and tapping on them or other components in the radio does not make the RF power jump up to 100w and go back to 80. The power supply operates my TS440 with 20A for 100 pep no problem.
I was able to get schematics from N6GW and his Kenwood page and I will get the bench setup for some signal tracing with my 'Scope. (Tektronix 100mhz) I was able to measure steady power without any fade-out from the Driver section in mw levels. So, it looks like problem in the driver transistors or the ceramic MR492's. These are easily replaced, but at $45 each I want to make sure only the bad one is replaced. This will be interesting to attack an electronic problem and hopefully I do not fry something in the process. I do not want to use 6M in my Flex radio.
And the next thing to look at would be the output side of the circuit that monitors SWR.
I really think the 'Scope will show me where the drive level or output device is failing. The bad thing about this is the SWR fold-back circuit might control one of the pre-driver stages to reduce power. The front panel display ALWAYS indicates 100W out. Even though I only see 80. It does accurately indicate the power dropping to 0 W as I talk into the mic. and recovering to full output.
Flipping the mode to FM and key and un-key the TX continually will make the power sometimes jump to 100 w and most times 80 w and then a key-up produces 0 w but climbs up to 80 like some sort of delay. This will be interesting to see how this displays on a 'Scope.
I thought someone here might have had a similar problem as, the TS60 and TS50 were very popular radios in their day.
Thanks for looking and sharing thoughts
Fred

[N4NYY]

My driver transistors went in my 746, and the power out was way lower than what you describe. I suppose you can pull them and diode check them.

[KA4POL]

Don't forget to check the temperature protection circuit. In case of overtemperature the detection port of IC1 in the digital unit goes high and reduces RF output. There might be a malfunction there. That's why I asked for the low power results.

[KA5IPF]

Stay out of the final and start by resoldering the the resistor packs in the DDS modules on the PLL board, total of 4 packs. Look carefully at the surface mount electrolytics on the tx/rx unit for signs of leakage. You are looking at the solder joints, they should be bright and shiny. If dull the cap probably leaked. Replace any that leaked. Also check the thru holes in the area for discoloration. That would indicate contamination by the leaking electrolyte and intermittent connections.

[K8AXW]

MOP: 

The front panel display ALWAYS indicates 100W out. Even though I only see 80. It does accurately indicate the power dropping to 0 W as I talk into the mic. and recovering to full output.

I don't understand this statement.  If the front panel ALWAYS indicates 100W out, then what says 80W?

If your rig always says 100W out and an external power indicator says something else, intermittently, then I would suspect the external indicator.

[NO2A]

I hope you are aware that the TS-60S was rated for 90 watts output,not 100. The TS-50 may have been a 100 watt rig.

[KC4MOP]

I hope you are aware that the TS-60S was rated for 90 watts output,not 100. The TS-50 may have been a 100 watt rig.

YES good note there....90W 6M. I'm not going to get to concerned with the 80W I see now.
The panel meter must not be calibrated coz it reads 100W and the Bird reads around 80W. Nothing is wrong with my test setup/dummy.
Getting more into the problem, the RF power will not come up to the max every time. Sometimes, I key and there's a delay in the RF power going to the 80 W reading. I key several times and the power comes right up and sometimes a delay and then a lower power.
The slow rise in power or key-up delay shows itself better in FM mode or CW where that is supposed to be max power all the time.
So, maybe I won't fault the RF PA stage and look into the resistor packs and electrolytics.
No matter what I do mechanically to the radio, tapping, banging, or whatever, I cannot make the power drop off or increase.
What will make this harder to find is, if the  problem is in the lower level stages on the TX-RX board. It gets pretty complicated in there.
Fred

[KA4POL]

In those cases the use of cold spray has proven quite helpful.

[AL7B]

The TS50 is known for issues with a 6V ref circuit that controls the power out.  If the 6v wanders the power changes.  Don't know if the same circuit is used in the TS60.  If so it is in the area of the power control circuit.

The bad news is that most of the components are on the bottom of the RX board.  As I recall capacitors become leaky.  I shotgunned my TS50 by replacing all capacitors while the board was lifted.  It is all surface mounted stuff so takes some time but not impossible.

What you discribe sounds exactly like what I went through on the TS50.  It has been awhile  since the repair but if needed I can dig back into the service manual for details.

Good luck with the project.