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Galaxy DX 66v swing mod

Discussion in 'CB Radio Modifications' started by 3006, Jan 9, 2017.

  1. 3006

    3006
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    I have a galaxy dx66v has been converted to mosfet.now on my cheap Palomar meter I can set dead key as low as 1watt high as ten watts and swing 35 watts so I assume it has a swing mod I don't want this swing mod I do not believe I enjoy the higher wattage but want durability loud but no distortion also I can only hear on one channel so might as well only talk on one I want this radio to be good barefoot in my van so I guess what I'm asking g if I should remove this mod if it has it and if so how can I locate it and what all needs to be done to remove it also if anyone else has a extra mic pcb I will buy it haha thanks in advance for the advice!!!


     

  2. 2FB327

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    Just because it was converted doesn't mean it has other mods done to it. Many of your newer radios have mosfets.
    I not sure what you mean about talking on one channel, etc. but I would recommend putting in on a good bench to see what it really is doing and if it's aligned.
    You can google mods for this radio and compare them with what your board looks like.
    Maybe post some photos and someone can spot something.
     
  3. LeapFrog

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    With a 1 Watt Carrier, he should be seeing 4 Watts P.E.P. MAX (Just enough to tickle the Amplifier), not 35 Watts P.E.P. [@ 100% Percent Modulation]

    This is likely a monster "wave form", a triangle form that is.. It's not correct A.M. that's for sure, you want a (pure) sine wave, and with modulation percentages like this I doubt the NPC mod has been performed, the harmonics would be 'huge', even with an NPC modification, you can't expect much over 100% modulation out of this raio w/out getting some harmonic distortion/IMD. (AFAIK)

    If the radio has been modified like he describes, it will surely splatter a few channels wide.
    (The adjacent channels at the very least will have interference, if not several channels wide.)

    This radio does not normally "swing" to max p.e.p. from any carrier setting or "dead key", unless the amc "limiter resistor" has been clipped, and a diode has been added somewhere.

    Usually these mods are common to find in older truck stop radios.

    On this radio, you want to check the following:

    *R238 should be 5.6k Ohm resistor with NO diode
    [In other words look for a diode @ R238]
    *TR53 (amc/ mod limiter) see if this transistor has been pulled
    *TR32 (alc/ audio limiter) see if this transistor has been pulled
    *Check if the resitor between R228 & R229 has been cut, this disables the amc ("mod limiter").

    *Look to see if a wire can be seen on the underside of the board that does not look factory, part of the NPC mod*

    *look for a diode (it may be in series with a resistor) added on the bottom of the board that does not look factory, this is for the NPC mod*

    *If you look at the corner of the radio near TR51 you may see the diode/resistor mod @C189 on the top side of the board, in this case you may only find a ceramic capacitor on the under side of this corner of the PCB by TR51.
    (the wire is left out sometimes in the NPC mod, if that's the case the regulator runs really hot!)
    (Also sometimes you will find just a diode somewhere [a few places to look] and no resistor in series.)

    *See if any of the coils have been mashed out to look like a spread slinky

    This radio uses the EPT360014 series board with two revisions, C & B.
    Here is a schematic. The full alignment info can be found here.
    Let me know how you get along, the locations I listed are the most common ones!

    Also:
    *VR13 is "A.M. Carrier Power High"
    *VR16 is "A.M. Carrier Power Low"
    Have a look at the Transmitter Alignment Page for the procedure for which You will need to return the radio to "factory" *only* after the "swing" modifications have been removed!
    (y)


    Best Regards
     
    #3 LeapFrog, Jan 11, 2017
    Last edited: Jan 11, 2017
    2FB327 likes this.
  4. StrangeBrew

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    Also try a quick Google search for "top gun modulator". It's a Magnum thing that some people have fit to other radios, it would give the swing you're seeing. Someone may have set your radio up with one.
     
  5. 3006

    3006
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    I appreciate all the info I'm gonna get to work on it this weekend (waiting on new mic pcb) really wanting to avoid having that splatter box radio I have a feeling this radio has seen a many of truck stops I'm just assuming it's a splatter box.I always get compliments from truckers on 19 but I've also heard some of there radios.
     
  6. sonoma

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    just to let you know the top gun modulator one told you about if it has one is in the R238 location. it will have a few wires on it and 2 of them go to R238 location . the same place they add a diode to for swing. swing is not a bad thing as long as the audio is right. the best thing you could to hear your radio is set up another radio about 20 feet from you with a good speaker on it and you can talk ino the radio you are wanting to see how it sounds and just listen what you sound like. the receive radio you will want to turn the rf gain down so you do not over load it when you are talking to see how you sound. this is the way a good shop does when they repair and mod radios. most truck stops just put a mod in it and send you out the door no matter how it sounds.
    I like the top gun modulator because it has a powered board you hook up to 12 volts and it has 2 wires on it that you can put a switch on it to kill the modulator where it works as stock or turn on the modulator for more audio and swing.. most shops do not hook up the two wires to turn the modulator on and off.
     
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  7. LeapFrog

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    Swing can be a bad thing if you want a true 1:4 ratio.
    1 watt d.k. swinging to 20 probably can be made to sound okay, but I doubt people running this kind of setup care about linearity?
     
  8. sonoma

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    I do not pay much attention to the 1 to 4 ratio. I watch the scope plus listen to how the radio sounds on a back up radio inside my 30 by 50 foot garage. I have it setting about 20 feet from me and I use a large good sounding speaker to hear how my radio sounds. I do not use the radios talk back as some do. if the audio looks bad on my scope and sounds bad on me radio to receive my signal and audio it will sound like trash in my vehicle or base set up. most people thast are trying to learn off the forums does not have a idea about using a radio to monitor how your radio sounds. I never call out for a radio check to ask how my radio sounds. I know myself before I ever put it in service and not rely on some one going down the street. all of my test are done on a dummy load and not an antenna as a lot do.
    just the way I do my radios for the last 20 years now.
     
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  9. LeapFrog

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    Nothing wrong with that at all brother, I like the steps you take to ensure your TX audio is proper.
    My preference is to run an AB bias amplifier w/ a 1:4 ratio, everyone has a unique station, & that's what is so great about radio! (y)
     
  10. sonoma

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    an amp is a different story. 1 to 4 usually gives the best sound on them. again I listen on my back up radio to see how it sounds when I set it up. amp set up is a total different animal in its self. a buddy of mine got me into radio repair years ago and he has been doing this since the late 60's now.he just started shutting down his shop just last year and he only opens it up for his old customers now. he use to open at 9 am then close around 5 to 6 or later depending on if he was busy. his shop is behind his home on a side street so he is always there. his Dad opened the shop in the early 50's then started him working on radios when he was in his early teens. he is 65 now. he showed me what I know about radios. he never advertised his shop at all. his business is word of mouth only. he was busy when other shops were on the radio trying to get people in. he always had a person in his shop for repairs. he would sell a new radio by order only and kept used ones in stock that he would trade for or buy from some one selling. he was basically just a repair shop. carried antennas for drivers was about it. if you go down to his shop when he was open you could not talk to him because he would have 2 or 3 standing around waiting for a repair. he basically had truck drivers for his business. he did a lot of mods on radios for drivers and built them slip seater set ups .
     
  11. 9C1Driver

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    Some one went to the trouble of doing a mosfet conversion to that radio I'm sure they re-tuned it as well. Have it bench tested at a shop with a scope, and have the variable power set for a low dead key of 2 and a high dead key of 6-8. If it has a decent signal on the scope leave it be and enjoy. Are you getting any complaints on how it sounds?
     
  12. LeapFrog

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    I think he just wants to undo the swing mod
     
  13. JoeDirt

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    Do you have a scope?

    Swing kits on Galaxys are fine, no harm done. Other radios not so much.....
     
  14. LeapFrog

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    Really, I can prove you wrong in a hurry with a (nasty) Galaxy DX66V.

    It will not be as bad as the worst swingy Cobra, but it will show you some Shark Teeth when set up incorrectly, add some crashing on the negative peaks and say night-night; ...Hello Splatter!

    Swing kit is a pretty broad term, if the radio in question has an NPC modification, things begin to change!

    Best Regards
     
    #14 LeapFrog, Jan 13, 2017
    Last edited: Jan 13, 2017
  15. JoeDirt

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    Well ya if its setup wrong, you can have a nice clean signal with a galaxy and swing kit. Thats why I asked about a scope. Swing kit/NPC whatever same crap.
     

: Galaxy

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