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KL203 Amp

Discussion in 'CB and Export Equipment and Accessories' started by Spinrock, May 10, 2017.

  1. Spinrock

    Spinrock
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    Greetings to all. New member here.

    My amp no longer gets warm ever. Red and green lights work and I checked the fuse and it seems ok. No contacts since this issue came up. RX is fine. Also when switching on the amp I no longer get the slightly higher background noise it gave when first installed. Less than a couple of hours run time on this unit. Hardly ever use it for TX. Any easy checks or is this pretty much a throw away situation?


     

  2. codeman

    codeman
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    Do you have a swr/power meter to check the output?
     
  3. Robb

    Robb
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    Sounds like you are new to radio, Spinrock
    No big thang; you aren't the first to make this mistake.

    Using/adding an amp to a radio is NOT a plug 'n play thing like one might expect. The amps have a maximum power input requirement; if you exceed it, the amp will pop. Usually this amp in particular requires no more than 1-1 1/2 watt AM 'dead key' (no modulation) out of the radio. A stock Cobra 29 (as an example) has a 3-4 watt dead key, so they need to be adjusted to accommodate the amp's requirements. Sounds like you weren't aware of that.

    Read on:

    http://cbradiomagazine.com/KL203.html
    http://cbradiomagazine.com/RM_Italy_KL203P_Amplifier.html
    http://www.worldwidedx.com/threads/rm-italy-203p-amp.66736/
     
    #3 Robb, May 10, 2017
    Last edited: May 10, 2017
    mechanic likes this.
  4. sonoma

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    these little amps are nice but over driving them is a no no. my buddy runs one of these with a 2950 but he has to turn the power down to low or it quits right away. had to replace his finals a couple years ago because he forgot to turn the radio down to low and talked on it.
     
  5. Tallman

    Tallman
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    W9WDX Amateur Radio Member, KW4YJ EXTRA class

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    What type of radio are you driving it with?
     
  6. sonoma

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    reread your question on the amp about a throw away unit. these units are normally a cheap repair. if quit due to being over driven the 4 mosfets in it went bad. just need to have some one that knows how to test it check it over. the mosfets are rather cheap. just time to replace them. even a small relay can go out and need replacing if bad.
    like Tallman asked what radio are you using with it and how many watts is the radio putting out? if too many watts put into it all it will take is one or 2 key ups to pop the finals.
     
    Robb likes this.
  7. Tallman

    Tallman
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    W9WDX Amateur Radio Member, KW4YJ EXTRA class

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    Nomad radio has a good posting on here about repairing these amps. There are two relays one is for transmit and the other is for the preamp. The SSB can pop the receive transistors and the relay won't work anymore. The relay can be removed and bypassed restoring function provided you did not over drive the finals.
    His posting covers all of that in this thread. If you are not a tech this might be over your head.
    http://worldwidedx.com/threads/need-help-selecting-a-better-transistor.213066/#post-586356
     
    #7 Tallman, May 10, 2017
    Last edited: May 10, 2017
  8. Spinrock

    Spinrock
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    Thanks for all the input. I am running a Uniden Bearcat 980SSB radio. Dead key is set around 1 watt. I had it done for me a about 10 months ago and it has talked about 10 miles max when it was working. I do have an MFJ-891 Cross Needle Watt Meter which I have never used. Thinking of hooking it up and see what I get. Got to figure that out first...lol. My SWR's are around 1.2 to 1.4 across the band. These were checked with an MFJ 259-C Analyzer. Running a Lil Will mag mount antenna on a 2004 Toyota Tacoma. I pulled the fuse out of the amp this morning and discovered the Amp Red led will fail to come on with out it. The pre amp green led works with or without the fuse in place? Again of course the fuse seems to be good.
     
  9. 9C1Driver

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    Based on that information the simple step is put the watt meter in line and see whats up.
     
    Sarasota Slim likes this.
  10. Sarasota Slim

    Sarasota Slim
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    Yep. That would have been my 1st step, before even asking questions.

    I like to gather as much pertinent information as possible, so I can ask more precise questions, and hopefully receive useful answers ;)
     
  11. Spinrock

    Spinrock
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    I did get it hooked up to the radio only and found it is putting out 1.75 watts Dead Key. However, I do not have a clue how to hook it up so it is reading the 203 while hooked up to the 980. Maybe I need a special jumper...?
     
  12. 9C1Driver

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    You need a second jumper. Radio - jumper - KL203 - jumper - watt meter - Antenna.
     
    Spinrock and 222DBFL like this.
  13. 222DBFL

    222DBFL
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    You need 2 coax jumpers and hook the meter up as follows.
    Radio to amp input port. Amp output port to watt meter input port. Watt meter antenna port to antenna. 1sr jumper will go from radio to amp. Second jumper will go from amp to watt meter. Make sure to turn your CAL knob all the way down as it will slam it to the corner if not when you have the amp on and key up.
    From what you have stated, you make have a bad coax connector as well, or some water intrusion. But placing the meter after the amp and checking its output, the way I showed is the way you should do it.
    Also get away from any and all obstructions and people for at least 50-75ft in all directions and also, make sure mic gain is all the way down before calibrating your watt meter. And remember to keep the calibration knob all the way down with the amp on before you try to calibrate it for checking the VSWR your enore system, from radio through amp and to antenna.
    Hope this helps and also check all your coax connections and make sure they are all good.l as well as your coax. Look for cuts and pinches in the coax or flattening of the coax. Then if you have a magnet mount antenna, make sure it's clean and dry underneath. Or if it's hard mount, make sure it has a good connection and it's not rusty or corroded under the mount. Again, hope all this helps and hope you get it resolved!! Good day.
     
    Spinrock likes this.
  14. Spinrock

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    Thanks guys. Great tips. I think I can do this now. One item that I forgot about is that the Coax connector ring from the Wilson Mag Mount antenna has been damaged and is no longer threading properly. Only hand tightened to check radio performance. Will have to order a new one to be able to use it other than checking in a sitting situation. Would never stay in place driving down the road.

    Now to find a source for the needed jumper. Any supply houses recommended?
     
  15. 9C1Driver

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    E-bay, truck stop, most any cb shop. Take your pic. You might find that the source of your problem is the damaged antenna. Just hope you didn't blow the amp because of that which is quite possible. When you decide to add an amplifier it is imperative that everything is in order. Quality antenna, antenna system install, SWR, proper grounding and install if radio, proper install and feeding of the amplifier, and proper drive levels for the amplifier. It should all be planned out ahead of time.
     

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