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Thread: TS 130S Power Output Problem - Any Tips?

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  1. #1

    Cool TS 130S Power Output Problem - Any Tips?

    I have a Kenwood TS 130 S on my workbench trying to isolate a problem with Transmit power output. This is an intermittent problem which possibly someone is familiar with and can help me solve.

    * Transmit power output is normal at about 100W out most of the time. Intermittently, the transmit power drops suddenly to about 20W. Occurs with antenna (low SWR) and dummy load testing. The power output will remain at 20W for a short time, then returns to full output of 100W without any action other than keying. The ALC level never changes with this power drop event. Adjusting the Carrier Level does not correct the power drop. Mechanical vibration does not induce or clear the power drop problem. Switch contacts have all been checked and cleaned with no effect. Potentiometers VR1, VR2, VR3, VR4 on the Filter Assembly have been cleaned and adjusted per the service manual.

    * The cooling fan for the Final Assembly never seems to operate. Fan motor is good. Should this cooling fan be coming on during a normal QSO to cool the finals? I can feel heat radiating from the Finals but the fan never comes on.

    Anyone seen this before ?

    Tnx, 73
    Jim NB5M
    jcain4u@comcast.net

  2. #2
    Join Date
    Jan 2008
    Location
    Lisbon, Portugal
    Posts
    311

    Default

    Is that transceiver solid state?

    If so, i would check the final output drive, which is certainly 2 transistors in a push-pull circuit.

    You may take them out and check them with a multimeter, for any leakage or short circuit.

    You can always replace them (always both), they´re not cheap though...


    Hope this helps!


    Keep posting!

    Regards from Portugal!

  3. #3
    Join Date
    Nov 2003
    Location
    Savanna, Illinois, the west coast of Illinois that is.
    Posts
    9,248

    Default

    Try tightening all the screws on all the boards. K9STH swears by this simple cure. I’ve used it on my TS120S myself and it really does seem to work.

    I actually took a Q tip and some tarnX cleaner to the parts of the boards where they make contact under the screw.

    Cleaning the contacts of the relays with tarnX didn’t seem to help much I managed to get a small piece of jewelers cloth for that job but I‘m told a dollar bill is just as good.

    My rig is working fine for the last year or so. I might have to do this all again some day but it is simple enough that I feel I will be able to do it again without to much problem.

    The fan on the back of my 120 rarely runs. When I was messing around trying to make PSK work it did start running at least once. It is very quiet and you have to look to see if it is going or not.
    KA9VQF

    Any tool is a weapon if you hold it right.

    “The only difference between stupidity and genius is that genius has its limits.” A. Einstein

  4. #4

    Default

    I just fixed a 120 doing the same thing. Where the antenna lead connects to the filter board the solder joint had cracked. It did not respond to vibration either which surprised me when I found it. The ALC never changed, the power would just drop on it's own.

    Of course this was after I resoldered the base of the finals and added a jumper which is a known bad area.

    Clif

  5. #5

    Default Intermittent RF output

    Had that with my 120 (very similar radio). Kenwood had problem in the design, relying on ground connections through the corner mounting screws, and issued a bulletin years ago.

    Just tighten up the screws on the corners of the module boards . . . should be about 1/8 turn or so. Never saw a rig this didn't fix, and I've seen quite a few.

    Gary WA7KKP

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