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Galaxy DX939 freq expansion mod?

Discussion in 'CB Radio Modifications' started by 2RT307, Jan 14, 2012.

  1. 2RT307

    2RT307 Sr. Member

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    I have a DX939 that I won in a contest a while back. I would like to mod it for expanded frequencies via the pll jump/two switch method. I can't seem to find anything on it, either here on the forum or CB tricks. Has anyone done one, and if so, what is the mod?



    Tnx and 73,
    RT307
     

  2. ThirstyBoots440

    ThirstyBoots440 Local Trash Talker

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    If I'm not mistaken, extra channels can't be done on the 939 easily
     
  3. grimace

    grimace Active Member

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    it does look like you could us a viagra board
     
    #3 grimace, Jan 14, 2012
    Last edited: Jan 14, 2012
  4. 2RT307

    2RT307 Sr. Member

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    Odd thing on this rig, you can turn the channel selector veeeerrry slowly between channels, and sometimes get frequencies above 40 and below 1. Can't remember which ones right now. But, that makes me think the PLL can just be jumped?

    73,
    RT307
     
  5. Robb

    Robb Yup

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    Don't think I would even bother to convert an AM only radio for extra freq's.

    If any radio has SSB; then yes freq conversion is desirable.

    Get a 959, add the freq switches/or a Viagra board, add a nice mic (D-104, CR-577, or Xtreme2018), and then give the radio a complete alignment.
    That should be able to knock something over on either AM or SSB. . .
     
    #5 Robb, Feb 20, 2012
    Last edited: Feb 20, 2012
  6. 2RT307

    2RT307 Sr. Member

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    Robb, lots of guys talk AM below channel 1. I won the rig, and it has a lot of bells/whistles on it. Just seems a shame to have a frequency display without anyplace fun to go!

    73,
    RT307
     
    PA770 likes this.
  7. 9C1Driver

    9C1Driver Sr. Member

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    You are correct, the freeband DX above 40 is mostly SSB but below ch 1 it's AM baby. I agree on the freq display as well, serves no purpose on a non SSB radio.
     
  8. 2RT307

    2RT307 Sr. Member

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    Took it to the tech today. It's done. :)

    [​IMG]

    [​IMG]

    Added 36-40 on the Pearce Simpson, too. (y)

    In both instances, the answer was adding a crystal. 939 now sports a switch on the side for the lowers. Channel maps? We don't need no stinkin' channel maps!

    73,
    RT307
     
  9. towerdog

    towerdog one-niner-seven

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    sweet, the lo-band of channels lines up perfectly too, unlike most PLL modded radios where channels overlap the same freq on different bands.
    only thing its missing is 10k, .195 is popular amongst the locals here, a good place to hide from all the drunks, jammers and idiots on the band
     
  10. Mudfoot

    Mudfoot Sr. Member

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    AM lower is still somewhat active locally.
     
  11. Z-MAN

    Z-MAN Member

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    I know this is an old thread, Ive got a 939 on its way and Im interested if I can do the P5/P6 mod. (nobody really answered the guys question). I guess I might have to when my radio gets here.
     
  12. 2RT307

    2RT307 Sr. Member

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    I never could find anyone that was able to jump the PLL, Z-man. My tech is pretty sharp, and he said he didn't think it would work due to the particular PLL on the rig. I'm sure you can try it once you put it on your bench. BTW, the crystal way works pretty darned good.

    73,
    Brett
     
  13. techradioman

    techradioman Member

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    Expansion of the 939 is the same as the 949 and 959,


    Channel Expansion Modification
    1. First, remove power to (unplug) the radio. Remove the bottom chassis cover of the radio.

    2. Locate J33 near the left-front of the main board. It is partially hidden under the small PCBs just above it. This is the controller you will be working with.

    3. On J33, locate the wires going into the P5 (Yellow) & P6 (Gray) positions and note their colors. These are the main frequency control lines. Follow both to each end and cut each wire at a convenient spot where it will be easiest to work on them.

    4. Install an SPST switch between the gaps in each wire. Do not cross the wires. In other words, you want each switch in-line with each wire. This will effectively "open" or "close" each wire's circuit associated with the PLL. This provides the extra channels. Locate the switches anywhere you'd like as long as they are easily accessible. One option is to use any existing switch located on the front panel of the radio due to the fact that it is so cluttered with switches and knobs already.

    5. Replace the bottom cover of the radio.

    Your radio should now be fully expanded to operate on the expanded frequencies. Here is a link to the roadmap for the above new frequencies
     
  14. Cutlass327

    Cutlass327 Member

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    Old thread, but exactly what I'm looking for, just have a couple questions.

    Since you are just changing how the PLL interprets the channel control, you are not really messing with the alignment, correct? I can do this myself, but I do not have the means to do an alignment.

    There also an addon board by Lescom, LC35, that you add in. They mention adjusting to bring it back onto frequency.

    Now, if I go either route, does the freq counter actually display the frequency you are tuned to?
     
  15. nomadradio

    nomadradio Analog Retentive

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    1: Changing the inputs to the PLL does not affect alignment, only the frequency the PLL will go to. If you go to a channel that's too far from channel 20, where the factory aligns the radio, it can affect performance. Might need alignment to make it work 20 channels below channel 1, or on channel 87.

    Might not.

    2: The add-on boards make bigger changes to the radio's PLL circuit, and may require adjustments to get them installed.

    3: The counter display in the Galaxy radios really does display the operating frequency outside the 40 channels.

    Best way to tell this on any radio with a frequency display is to turn the clarifier or "fine tune" knob.

    If this changes the frequency that's displayed, it's a counter.

    And if there is no change, it's a programmed display, not a counter.

    73
     

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