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RM KL203-P

Discussion in 'Amplifiers' started by Dr DX, Feb 1, 2018.

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KL203-P high low mods

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    5 vote(s)
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  2. 2

    1 vote(s)
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  1. 2NC995

    2NC995 DAN

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    I gotta admit, I have never been a fan of preamps until the past couple weeks. The one on my DX500 has helped me pull in a couple late night contacts. If the QRM is up...forget it. But later in the evening I’ve been running it and liking it.



    Sooooo...for the 203 I bought one with a “P”.
     
    Slowmover and Shadetree Mechanic like this.

  2. nomadradio

    nomadradio Analog Retentive

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    The power supply you use doesn't say "Pyramid" on the front, does it?

    If so, that could explain the whole problem.

    73
     
    Slowmover, tecnicoloco and Handy Andy like this.
  3. Slowmover

    Slowmover Elmer

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    Need to pair it with this (mobile) or a separate unit inline with a Hi-Fi speaker (as that concept used in this game).

    F131AB83-F6A9-4B65-B4D1-ED7470B1D023.jpeg

    DSP

    A KL203P isn’t same exact circuitry as the 203 (plus pre-amp, sorta), it’s a slightly different critter we’ve been informed by His Tallness

    But given working conditions made quiet for a given vehicle:

    Turbo-supercharger engaged when indicator lamp goes from green to red to pure flame.

    Gotta really work the prop rpm & fuel mixture on the WM SPKR to maintain the best climb rate with those Pratt & Whitney’s.

    And you may find the spark advance (clarifier) just slightly off in a course heading change. (Fast, hard & hot engine re-start; AKA all radio controls).

    787DD7ED-D4F4-4538-8AE5-27E7599AB32C.jpeg
     
    #48 Slowmover, Apr 20, 2020
    Last edited: Apr 20, 2020
  4. Shadetree Mechanic

    Shadetree Mechanic 808 On The North Side of Dover

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    Welcome General Joe! Those little 203 amps have got to be the best bang for the buck I have seen in an amp. The keying circuit in my 203 takes very little power to trigger, like less than half a watt. The P version might be different. One time I forgot to switch into SSB mode and was still OK as my Galaxy 99v was wringing 200w peak out of it. A single final radio might not be able to do that, so I am going to ask a silly question; Do you have it in SSB mode on side band?

    So if it is in SSB mode and chattering, but AM is ok then it would sound like the sideband capacitor went out. Usually there is a capacitor used in sideband mode to hold the keying relay on for the brief instant between words. I have also seen radios not able to keep the side band mode engaged because of their really low power. The sideband mode in my X-Force 4 pill needs a certain amount of drive power in side band mode to keep the relay keyed, even with the side band relay. This is the main reason people use a separate key line from the radio to the amp as it forces the amplifier to key whenever the radio does with a separate wire between them.

    So to sum it up, there might be a problem with the amp. The suggestions about power supply and wiring might also point to the problem. But to me, if it used to work the way it is, and it works in AM mode, then that points the finger at the side band mode. Maybe the switch is getting goofy? Flip the switch about 20 times and see if it starts working, might just be dirty contacts (surface corrosion) from sitting?

    Chris

    PS: Something else you could try real quick is to turn the power up on the radio a little to see if that makes the chattering quit.
     
    #49 Shadetree Mechanic, Apr 20, 2020
    Last edited: Apr 20, 2020
  5. 2NC995

    2NC995 DAN

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    I agree with all of the above.
     
  6. Slowmover

    Slowmover Elmer

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    With yesterday’s changes to my Peterbilt (that thread: 579 Pete Install) I’m running the KL203P pre-amp “on” In daylight running and showing less than half the meter of S-units noise (6-7 S-Units) with Galaxy 99v2:

    1). RF GAIN maxed
    2). SQUELCH “off”
    3). ANL/NB “on”

    West Mountain Radio ClearSpeaker

    1). volume at 1200
    2). Filter at 1000

    Adjusting the volume of radio to volume on amplified speaker is key.

    Skip today now am headed south on IH81 at Maryland line. Savannah, GA or the truck wash at Nashville, TN.

    This is a “not” intrusive sound pressure level. Gets that fainter skip up close.

    Hearing AROUND the noise pays the freight.

    .
     
    G GOLLY WAlly and Handy Andy like this.
  7. Handy Andy

    Handy Andy Do Your Research First, Then Decide...

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    Nothing like separating the "Wheat from the chaff..."

    Amen!
     
  8. aeromojito

    aeromojito New Member

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    I know this thread has a little age on it but did anyone ever manage to mod this amp to accept higher power? I'm trying to avoid lowering the radio's power. The amp won't always be on and I might use it with different radios, all of which have 4 watts and barely above stock modulation. On the 2 resistor version, does the parallel resistor go on the relay side or transformer side?
     
    Slowmover likes this.
  9. 9C1Driver

    9C1Driver Sr. Member

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    Probably not worth messing with, it's pretty much a throw away amp when you smoke it. Every small amplifier you buy will have suggested drive levels. This means you will end up adjusting your radio to better match up with the amplifier you choose. What radio do you have?
     
    Slowmover likes this.
  10. sp5it

    sp5it Master of puppets

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  11. aeromojito

    aeromojito New Member

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    Thanks for the calculator. I have a President Bill that will probably be mounted in the car. I might also use an RCI 2950 or a JCPenney 6247 when I get them working. The bigger radios would be temporary hookups for DX when I'm by myself. I know it's easy to adjust the President Bill. I still might do that. I just like the idea of standardizing the amp for a 4 watt radio.
     
    Slowmover and Shadetree Mechanic like this.
  12. aeromojito

    aeromojito New Member

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    I also noticed there is a 180pf capacitor in series with the output. That's a reactance of 32 ohms at 27 MHz Doesn't make much sense to me.
     
    Slowmover likes this.
  13. Holydvr

    Holydvr Active Member

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    I popped one of these open that was given to me smoked, and I put 13n10’s in it. It was something like 9.99 for 20 of them. Only reason I mention this is how many say its a throw away unit. I have been talking on this little thing for over a year just about every day in the mobile since I repaired it.
     
  14. Shadetree Mechanic

    Shadetree Mechanic 808 On The North Side of Dover

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    Did you just drop them in? Or did you have to make any changes to the bias or tune? Does it make the same power? Sorry for all the questions, I am going to get some 13n10 transistors to have on hand.
     
    ForestRunner98 and Slowmover like this.
  15. 9C1Driver

    9C1Driver Sr. Member

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    The reason I say these are throw away when you smoke them is this. If there is no one local to repair it there are several costs. 1) shipping both ways 2) parts (finals and anything else that got toasted). 3) shop labor for the repair. When you add that up and then consider what a new unit will cost in most examples your better off buying a new one.
    I would be curious to find out what finals were in it new, and are the 13n10's actual drop in replacements? Nothing else was burned up and no damage to the foil on the board? If all that worked out in your favor that's good for you.
     

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