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STALKER ST-9FDX

Discussion in 'General CB Services Discussion' started by DIRTY HARRY, Feb 11, 2008.

  1. DIRTY HARRY Member

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    Hi does anybody know how to increase the slide for 5+ khz either side of the 12'o clock position on a Stalker ST-9FDX??, Mine currently only slides about 1 khz either way & it would be nice to be able to get on the zero's,as it already has a 10 khz flicker switch for me to get on the alpha's, the pc board number is pc-893


     
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  2. freecell BANNED

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    what's the current operating voltage of the clarifier?
     
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  3. DIRTY HARRY Member

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    ABOUT 7.3 VOLTS, I DID TRY INCREASING IT TO 8.5V BUT IT DID'NT MAKE MUCH DIFFERENCE WITH THE SWING,I EVEN TRIED THE TRICK WITH PUTTING A RF CHOKE INLINE WITH THE VARACTOR DIODE, WHICH I THINK IS D31 & THAT ALSO DID NOT WORK, IM WONDERING IF SOME OTHER COMPONANTS ARE SUPPOSED TO BE REMOVED LIKE THE SLIDE MOD FOR THE STALKER XX HOMEBASE? EXCEPT THEY ARE TOTALLY DIFFERENT PCB BOARDS..
     
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  4. loosecannon break on through

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    here is all the info i have on this chassis. i hope it helps:

    to mod clarifier:

    Remove D33.
    There should be an orange wire going from the clarifier pot to R168 on the PC board. Remove this wire from the PC board and connect it to the cathode of D44 (7.5 constant volts)

    There is a resistor (R231, 6.8K ohms) going from the violet wire to PC board ground. this value can be lowered to get more slide, and some people just replace it with a jumper, but to protect the power supply; a diode should be used instead.

    you can also increase the B+ voltage to the clarifier to increase slide.

    after doing these mods, you can try adding about 5.6uH to the varactor diode (D31). or you can try replacing it with an NTE612, 613, or 614.
    they are supposed to be the closest thing we have to a super diode, but i have had mixed results (mostly bad) in using them.


    oh yeah:
    VR11 AM power
    VR5 AMC
    VR7 ALC
    VR3 FM deviation

    here is a link to a good schematic:
    http://www.cbtricks.com/radios/teaberry/stalker_ix_fdx/graphics/stalker_ix_fdx_sch.pdf


    good luck,
    LC
     
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  5. freecell BANNED

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    a 5.6 uH choke needs to be in series with D31 on the anode side of the varactor. if you're going to replace D31 with anything try the mv1404 first.

    http://www.firecommunications.com/trdbase/mv1404.pdf
     
    Last edited: Feb 12, 2008
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  6. loosecannon break on through

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    freecell, thanks for the tip on the MV1404!

    does this also work for broadbanding the VCO's on the MB8719 radios?
    (cut trace to pin 6 of VCO and add "super diode")

    thanks for any info you have on this,
    LC
     
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  7. DIRTY HARRY Member

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    d44 has 1.62 volts d.c constant.
     
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  8. DIRTY HARRY Member

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    Last edited: Feb 12, 2008
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  9. loosecannon break on through

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    not sure what to tell you about D44.
    it is a 7.5 volt zener diode according to the schematic.
    are you sure you measured on the right side of the diode?

    it looks like there is 8 volts constant available at the junction between R56 (1K) and VR2.

    i have never had one of these radios; this info is out of an old book.

    im sure you can find a constant 8 volt source by tracing around the radio with the schematic if that one doesnt work.

    good luck,
    LC
     
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  10. freecell BANNED

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    yes. it's required for 10M conversion in MB8719 boards along with a xtal change.
    either way it's the one to use.

     
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  11. Switch Kit Active Member

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    The Super Diode ! :drool:
     
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  12. loosecannon break on through

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    Rick Jackson (did the re-draw of the 148GTL schematic on cbtricks.com)
    says he uses the SVC251 or the BB809 for these kinds of things.

    are they the same as an MV1404?
    LC
     
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