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Final stage resuscitation CB PRESIDENT JACKSON IRF520N FQP13N10

Adamcall 25593 46
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  • #31
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  • #33
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  • #34
    Thenatoorat
    Level 13  
    Once, I also had a problem with these transistors (originals). A good and cheap solution is to fit a Grant power amp. Lest I was talking crap. I found Grant's schamt in the book "service diagrams" then there was still a problem with the net. It turns out that these are quite similar radios. The final stage in the Grant was on a different transistor (price around PLN 5). All you had to do was swap the collector with the emitter (but I don't remember exactly anymore).
  • #35
    brendy2
    Level 10  
    The 5V6 zener diode is a protection that the voltage on the IRF520 gate does not exceed this value and does not fulfill any other function in this case.
  • #36
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  • #37
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  • #38
    xpascal
    Level 11  
    The Jackson power stage is a linear amplifier and the use of a switching mosfet (and this is the IRF) is an average idea at 28MHz. Yes, the transceiver will deliver power, but the signal will be of terrible quality. This applies not only to harmonics (these are screened on the low-pass filter), but also to signals close to the transmitted signal. To show what the effects may be, I will provide a comparison of the two measurement results. The first is the power level where there is an obvious design error or there are problems with the BIAS:
    Final stage resuscitation CB PRESIDENT JACKSON IRF520N FQP13N10

    And this is what it should look like (Yaesu FT1000Mk5):
    Final stage resuscitation CB PRESIDENT JACKSON IRF520N FQP13N10

    Let me mention that originally President Jackson does not belong to a device with a "clean" transmitter (hardly any CB is "clean"). So if you replace the transistor with an IRF, which you drive badly (and you matched the circuits correctly?), You will get the same effects as in the first photo and it will de facto break the transmitter.
    There is one more important problem there. The circuit on the previous page actually has a wrong gate polarity that will cause nasty interference. I have to search, only found good elaboration on improving efficiency, the problem of IMD is also described there. Here is another study very good in my opinion.

    This Jackson MUST be measured on the analyzer. Because you probably made a noise generator.
    So what is such an IRF suitable for? For power amplifier class C or D (telegraphy, FM, RTTY). That's where it works great.
  • #39
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  • #40
    Elektronik223
    Level 18  
    The problem with the schema deficiency is that the MOS-FET
    it works linearly in a narrow range of gate polarization.
    * 4.674 gate polarization [V] +/- 1.2%
    * stabilized voltage 5.1 - 5.6 [V] and to the voltage divider
    the above key conditions were not met in the system.
    The point linearity is floating.

    MOS-FET transistors, unlike Bipolar ones, work with voltage.
    voltage should not exceed in total Ugs 10 (15 *) [V]
  • #41
    Elektronik223
    Level 18  
    By the way, instead of the IRF520 / IRF520N.
    I suggest FQP13N06L.
  • #42
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  • #45
    Elektronik223
    Level 18  
    On the occasion of the experiment, you can swap FQP13N10 and IRF520N, the IRF520N should be given more power. The FQP10N10 in place of the current IRF520N will reduce the signal from the control stage less.

    Added after 25 [minutes]:

    Adamcall wrote:
    buddy pawlik722, except that the power consumption jumped up slightly, the radio works one hundred percent correctly.
    As for the question about the difference in the schema, compare yourself with the original schema.


    From Mitsubishi experiments (RD16HHF1)
    http://www.mitsubishielectric.com/semiconduct...rfdiscrete/siliconrfdiscrete_lv4/rd16hhf1.pdf

    Suggested Gate Source voltage (Ugs) max 4.7 [V] at Uds 12 [V]
    What voltage do you have in your solution on the gate?

    With FQP13N06, PA M0RZF constructions (see IRF510)
  • #46
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  • #47
    Elektronik223
    Level 18  
    Few of the above-mentioned designs are better than the IRF510, you may be tempted to say that they are worse.

    As replacements? you can experiment to re-establish the dynamic parameters of the systems. Well, you have to recount the RLC circuits. taking into account the dynamic parameters of the substitutes.

    SiHF510, (IRF510) vishay

    available here:
    https://www.elfaelektronika.pl/elfa3~pl_pl/elfa/init.do?item=71-148-04&hst=1