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doesn't make sense to me

Discussion in 'General CB Services Discussion' started by 1iwilly, May 26, 2021.

  1. 1iwilly

    1iwilly Well-Known Member

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    did you watch the video when the radio it's set at either 1/2 or 1 watt ???
    this not an amp issue a bird meter issue it's a radio issue again at that power lever the modulation starts falling off but not at higher lever why critical because that happens to be the set power to run the solid-state 200




     

  2. 1iwilly

    1iwilly Well-Known Member

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    here is an updated ok been the same mod is on my 2000 while in the 1/2 watt dead key same issue now just for shit's and giggle i cut r131 problem solve r131 is causing it to act like that at very low power and now modulation does not fall out. the question is how do i fix it so i can still have r131 intact
     
  3. freecell

    freecell Active Member

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    reconnect r131.
    check amc control vr501 and make sure it is adjusted to the fully clockwise position.
     
    #48 freecell, May 29, 2021
    Last edited: May 29, 2021
    NZ8N likes this.
  4. Handy Andy

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

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    Again,
    • R127 - Lower it to 1K,
    • R166 - Raise it to 10K
    • R165 - Lower it to 1K
    IF you do just one, make it R127...

    IF you can do all three you won't have the "fall-out" or fade away you'd get from Limiter staying on too long.
     
  5. 1iwilly

    1iwilly Well-Known Member

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    ok will try today and report back remember i did r127 only and there was no change


     
  6. 1iwilly

    1iwilly Well-Known Member

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    ok did as you wrote turn the radio on with no modulation at all so i started back words 1 resister at a time put R 127 back. while r165 is 1k and r166 is 10k now i got modulation back with a little improvement compared to my complain for some reason r127 no doing it for me


     
  7. Handy Andy

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

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    Boy, you do have some pieces of work...

    Screamers, well, if that is what you want, R131 might need to be removed, but warn your neighbors first - but the R131 limiter really?

    As said earlier, R131 changing it, won't do much, you have to take on and reduce the power going into the AMC circuit the Input that goes to the Limiter amp...that's thru those resistors and their divider design.

    R127 and R166, R165 vales were chosen so the original STOCK design would be within FCC limits - R127 simply trims output of one (AMC) to help with ALC on the other input - all inputs are "terminated" in some fashion to help meet the levels so the switchover - when the power is being produced in the other side, isn't killing the other section

    When R127 is/goes too low, it won't help on ALC either - so you'll have to look at R166 and R165. for your AM....

    Really swinging RWOB mods - you trim R165 to a low of a value as 560 ohms, and R127 - to same value as R165 (balances) and you're going to have to run the Mic Dynamike control ride it, if you're on SSB mode so you can even use an amp without killing it.

    A quick ADD...

    You're ALC is still on when you disable AMC by removing R131 - Adjusting R127 without AMC even being enabled - and you still have fallbacks or FADE?
    • - then ALC will need more work to handle your swings.
     
  8. 1iwilly

    1iwilly Well-Known Member

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    thanks, andy been r165 and r166 did make it a diff I'll let it be for now

     
    #53 1iwilly, May 30, 2021
    Last edited: May 31, 2021
  9. SIX-SHOOTER

    SIX-SHOOTER Sr. Member

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    I have the same meter that you use for PEP but I use the Three Autek WM-1 meters for most everything except my 6 meter antenna where I use a WELZ SP-600 with a K4DPK PEP Kit in it so I can monitor the ICOm PW-1 amplifier on 6 meters.All of my meters read PEP even for VHF/UHF just in case it's needed.I have no need of a wattmeter that reads just Average power.

    SIX-SHOOTER
     
    Slowmover likes this.
  10. ExitThirteen

    ExitThirteen Grumpy and Cranky

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    Quick analysis/description of this mod.



    I know I say ALC a couple of times in there, I meant to say AMC.


    ~Cheers~
     
    #55 ExitThirteen, Jun 3, 2021
    Last edited: Jun 3, 2021
  11. AudioShockwav

    AudioShockwav Extraterrestrial Admin
    Staff Member

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    Thanks for taking the time to put this up.

    73
    Jeff
     
  12. 1iwilly

    1iwilly Well-Known Member

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    thanks for taking the time on this but again my main complaint if you watch the video on my 148 when the dead key of 1/2 watt or 1 watt as soon as I started talking the watts would start dropping off again only at that low power level for variable power I'm using the rf gain knob but on the 2000 i'm using the SWR calibrate knob I've gotten good clean audio on the 2000 barefoot or with the amp on 148 i'm still trying to find the power leak thanks again for taking time for a better undestanding

     
  13. ExitThirteen

    ExitThirteen Grumpy and Cranky

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    I would suspect a bad capacitor, has the radio been fully recapped? My 2000 GTL was fully recapped 4 years ago, and it is in constant service, it doesn't sit unused. Even though the mod was not designed to be ran at 1/2W to 1W deadkey, your audio should not fade or fall out, so I would suspect a faulty capacitor.


    ~Cheers~
     
  14. 1iwilly

    1iwilly Well-Known Member

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    well for shits and giggles i tried a different variable pot and it's not doing it anymore shit does happen and your keyword =Even though the mod was not designed to be run at 1/2W to 1W dead key, point taken thanks once again

     
  15. Ed Cole

    Ed Cole New Member

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    Wow.....thanks Andy! You got rid of my headache better than aspirin!! I was gonna try to explain that but....well....you know.......;-)
     

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