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What is this mod? Stryker 955

Discussion in 'CB Radio Modifications' started by loosecannon, Jul 18, 2020.

  1. loosecannon

    loosecannon Sr. Member

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    found this on D-rail's channel.



    can anyone tell me what is going on inside the radio with this mod?
    LC


     
    Tokin likes this.

  2. Shadetree Mechanic

    Shadetree Mechanic 808 On The North Side of Dover

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    Watch the meters closely. It doesn't do what he says it does a few times. One knob effects the other. Would the hi and low power pots do this?

    Or two capacitors with the pots across them as a swing kit?
     
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  3. Tokin

    Tokin 42Zero Tampa

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    Ill have to watch this again.
     
  4. 543_Dallas

    543_Dallas Sr. Member

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    That's the Fauk Up a good radio mod. Does anyone have any personal experience of how long this stuff lives after it leaves the meth lab...I mean CB shop? 130 watts is insane. I turned mine down from factory spec to clean it up. These guys obviously have superior skillz.
     
  5. Tokin

    Tokin 42Zero Tampa

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    But wasnt that 130 on a Dosy that looked like it was dragged down 5 miles of bad road 15 years ago?
    Smells to me like its now nothing but a piece of test equipment used to squeeze more BBI watts for his videos because i dont see this radio lasting long as a daily driver.
     
  6. 543_Dallas

    543_Dallas Sr. Member

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    You read my mind.
     
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  7. Justme

    Justme Well-Known Member

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    It is quite simple.
    All amateur radio's have 2 100 watt continuous output transistors/fets running 100 watts clean output, each transistor/fet running 1/2 power.
    Cost a bit more, but all my radio's worked fine for 22 years and still do.
    11 meter radio makers don't worry about that, they just push the transistors/fets to the maximum specs, damned be spectral purity.

    Then those radios mostly get the golden screwdriver treatment, amplified microphones driving the output transsistors/fets into absolute saturation and be damned about spectral purity.
    Looks good on the el cheapo meters, but the rest of the frequency users will not be happy.

    I never peaked 11 meter radio's, just added a clean P.A to it with low pass filter if i needed more output.
    Same now using my ham gear, FT 991 A drives the Heathhkit sb-1000 up to 700 or 800 watts even there i don't push for the last watt.
    I rather leave some headroom for the new 3-500 ZG.

    But what do I know eh? ;)
     
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  8. 543_Dallas

    543_Dallas Sr. Member

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    You're not familiar with exports are you? These are cb radios that are sold as ham rigs to get around the legal tape.

    That rig has 4 switching fets for finals. I understand they aren't in parallel as the advertising makes you think. Predriver, driver and 2 finals.

    The devices were FQP13N10 transistors and I believe some use IRF520. They are not 100 watt devices. The datasheet doesn't say because they were designed for switching, not RF amplification. The last time I bought some they were less than 50 cents a piece.
     
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  9. Justme

    Justme Well-Known Member

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    I repaired more export radio's here as I care to remember in the days 11 meter was popular here, i've seen any modification in and out of the books and repaired the effects of them.
    Current amateur radio's also run fets in the P.A. like my new FT 991A and as my FT2000-D had in there for 200+ watts output on 50 volt.
    The FQP13N10 is normally used in switched mode supplies and as switching transistor, can be used for HF, P.A's with 4 of them are good in A/B class for 50 watts clean output.
    See: http://lz2jr.com/blog/index.php/mosfet-linear-power-amplifier-50-watts/
    read the data sheet, that will tell you enough.
     
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  10. Shadetree Mechanic

    Shadetree Mechanic 808 On The North Side of Dover

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    I would like to see this thing on a scope. I don't believe its possible to raise avg power and lower peak power without flat topping. Its the same waveform measured two different ways after all. It would have to be some kind of compression like on an audio signal, except done on the PA stages? Is that possible?
     
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  11. Handy Andy

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

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    I can just imagine the extra weight of solder that needs to be flowed across and fill up\in (Thickness) the traces leading to the finals from the power supply branches running thru that radio.

    Else with what it uses - it has enough trouble with simple amp branches now.- some trace branches are Not meant for that power draw - at least at the meter showing 14.xx - tells me the "tap" for the display and what is happening inside - they're muting the sucking sounds of current being drawn - there's a lot of work done inside to obtain that...

    upload_2020-7-19_11-22-22.png
    Secondary thought...

    I don't see the use of an Ammeter in there - can't prove much...

    To do the effect - going back to another posters comment ...

    Hi and Low power settings, yes, but...

    Singular - no, you'd need the "pots" to act as a "balance control" to attain these readings...

    I could go on...
     
    #11 Handy Andy, Jul 19, 2020
    Last edited: Jul 19, 2020
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  12. Justme

    Justme Well-Known Member

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    They also don't show a spectrum analyser either, wanna ask why? LOL.
     
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  13. 543_Dallas

    543_Dallas Sr. Member

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    That is correct but how does it apply to a Stryker 955?
     
  14. NZ8N

    NZ8N Well-Known Member

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    Actually, he shows a Spectrum Analyzer that goes "fuzzy" when he modulates it, but no Oscilloscope pattern is being shown at any point in the video. I would have to watch it again, but does he even have an O'scope on his bench? The video is very jumpy, swinging from one end of the bench to the other, then back, too much side to side motion. If I were to set up a bench with test equipment, I would have them all in as close proximity (side by side or on top of each other) so I can see everything that is going on at the same time, without so much head jerking. Same goes for the camera viewpoint.
     
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  15. Handy Andy

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

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    If you listen carefully to the audio - you may have a clue as to what is happening...

    One deals with the Limiter ...

    The other deals with how much audio envelope passes into the regulator...

    One control affects limiter you can hear that in tone "drops" as the carrier drops...

    IF you did that with ordinary AM Power adjustment - it would be screaming at low power - DOSY would be swinging all over the place.

    So one controls Limiter (ALC/AMC stuff) while the other controls the AM Power itself. (refer to Galaxy TR53 33HP)

    upload_2020-7-19_12-30-17.png

    He does issue the disclaimer of the 30 watt "limit" which is correct. There is only so much power that the "regulation" side of the AM Regulator (not the pass transistors) can put into the regulator before "fuzz-out" - there's too much bias for the audio drive from the 4558 chip to push thru (washes out).

    Note D92 is connected thru LO-Power contacts to VR12 to handle swing on low power - envelope to carrier swing issues...
     
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