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Schottky Diode Mod For Galaxy DX 94 HP ?

Discussion in 'CB Radio Modifications' started by Wire Weasel, May 24, 2009.

  1. Wire Weasel

    Wire Weasel Senior Moment

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    Anyone know of receiver mods for the 94HP Class to improve/reduce noisy receive?



    Thanks!

    [​IMG]
     
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  2. loosecannon

    loosecannon break on through

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    should be D1, D2, D30, and D31 for the diodes.

    the transistor to change will be Q17.

    the parts list shows it as a 2SC1674 but i think Galaxy has since improved that part and is using a 2SC2986 or 2987; cant remember.

    the transistor they are using now is just about as good as the 2999.

    i didnt notice any difference when i replaced it in my 959.

    the diode changes however, will help a lot.

    dont forget to check Q54 to see if its a 2SB827 and not a 2SB754.

    pretty sure Galaxy is using the 2SB827 exclusively now, but still worth checking.

    if you do want to replace Q54, the 2SB817 is the part to use.

    good luck, nice radio,
    LC
     
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  3. Wire Weasel

    Wire Weasel Senior Moment

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    Thanks LC ! I'll check into all of this.

    What's the part number for the Schottsky? TNX
     
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  4. loosecannon

    loosecannon break on through

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    they are 1N6263 or, if you cant find those, you can use NTE583's.
    either will work the same.

    you can get the 1N6263 from mouser electronics.

    here is a link:
    1N6263

    hope this helps,
    LC
     
    #4
  5. Robb

    Robb Yup

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    The transistor replacement is a 2SC2999; but there is a better version of it. The Sanyo 2SC2999 "E" is a bit more costly but is the 'cleanest of the clean' amping transistor. They can be had from B&D Enterprises:
    B&D Enterprises: Part #2SC2999E-SPA

    Two of the diodes are part of the detection circuit, and can make it a bit too sensitive - in the sense that they can even overload the receive. The other two diodes designated are used in the noise blanketer circuit. Cobra 29's only need 3; most other radios need 4. Truth is, the transistors are the parts responsible for knocking down the noise and improve the signal level.

    Some radios often will have a better receive if two 2SC2999E's are used - one for the first IF stage amping and the other for the SSB receive amping. Their advantage in use is to give the receive more signal gain before noise. The diodes aren't always the most popular mod, but the transistors are always welcome to any radio - IMO. Personally. I would do the diodes too - I have done this to all of my radios when adding the transistors. After these mods, realignment of the radio isn't necessary - unless it needed it to begin with. These mods cannot right an out of tune radio; they just clean up its act favorably...

    I've done a couple of Cobra 29's and 148's with really phenomenal results. Some think these mods are petty; I think these mods are useful and quite noticeable. I don't know what kind of IF transistors are in my Galaxy DX 99V. But if they are substandard and be cross exchanged, I will put the Sanyo 2SC2999E's in it - too. The receive in the Galaxy is already very nice, but it will still work better with the transistor mod.
     
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    Last edited: May 26, 2009
  6. Wire Weasel

    Wire Weasel Senior Moment

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    Thanks Rob !! Hey, still looking for the part # for the diodes.

    TNX 73

    [​IMG]
     
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  7. Robb

    Robb Yup

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    THE Shottky diode number is a 1N6263, or a ECG583(?) I use the 1N6263. Thet are pretty cheap, and can be had for as little as $.03-.08 each. I would buy the best brand if available, since you don't need a lot and they are cheap. Buy the ST Micro or the ECG parts will do just fine if that is all you can get. The Sanyo Transistor is really the key...
     
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  8. Wire Weasel

    Wire Weasel Senior Moment

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    Many thanks Rob, this will make a great reference thread for future use.
     
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  9. 505

    505 Member

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    Fisher technologies schottkey receive kit.

    Fisher technologies has a nice receive kit for all
    radios. Please follow this link for the details.

    Fisher CB Radio Technologies - DX Receive Kit & Manuals

    They give you all the parts and instructions for $7.00.
     
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  10. morseguy

    morseguy Member

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    I just received the kit from Fisher.
    I'll keep everyone informed of my results.
    Doc, 599, Boston Mass.
     
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  11. morseguy

    morseguy Member

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    I completed the kit and did notice a moderate improvement. I was a bit nervous of replacing the N.B. diodes since they very different looking compared to the new Schotkkies.
    The NB works fine.
    Overall it was a few dollars well spent.
     
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