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Magnum S-9

Discussion in 'CB and Export Equipment and Accessories' started by nickr, Nov 16, 2020.

  1. nickr

    nickr Member

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    Hi from the UK and thanks in advance if anyone can help. I recently purchased a Magnum S-9 boxed and in almost as new condition. The radio seems to work well other than the clarifier being about 1Khz off from the center position and the KC shift range is only about 4Khz each way. (I'm planning to send the radio out for a tune ASAP). My query is that I thought this radio was supposed to have variable power output in all modes. Currently only AM is variable. Does anyone know if some of the radios were made like this from the factory? I believe it's one of the earlier models as it has the 2 2SC1969 finals.
    Thanks, Nick.


     

  2. Handy Andy

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

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    upload_2020-11-16_16-42-20.png

    And you'd be correct...​

    Sigh...this may indicate that someone "dumped" the radio...

    Got it Fixed after getting "broken" and the sold it off...

    OR worse, scavenged it for parts, like the Tog-Gun-Modulator (TGM) a little black box of a piece they took from this radio...it would explain why you don't seem to have RF control...it has an output line that goes to the front panel thru a Potentiometer.

    upload_2020-11-16_16-59-43.png
    VR21 controls, or pre-sets trim - that potentiometer - on the front panel RF Power control. Thru a header labeled P102/J102 - goes to the "Talkback (AMT) and RF Power" Dual knob.

    If VR21 isn't hooked up, like they removed the TGM module - then you wont have any control.

    So for you to have AM ONLY control - hmmm...verify the TGM is in there - on the foil trace side if you can't find it in the component side.

    Else start looking for cut limiters...AM Power (Regulator section) TR53 and TR32 even see if you have an SWR Protection board - if soldering has been done to the innards - or it's been roughly handled (think Drop Kicked shipped via UPS) then you may have a bigger problem.
     
    nickr and buickid like this.
  3. nickr

    nickr Member

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    Great reply and thanks for that. I'll remove the case and check. I'm hoping that's not what's happened to it. I can definitely see a difference in what the power meter reads with the Top Gun Modulator switched on. i.e turning the power down and speaking into the mic causes it to swing, although you can't hear any difference through the talk back function (AMT). It sounds the same in standard AM as AM with TGM switched on. Before I bought the radio I actually spoke to the owner who told me he'd had it from new and had hardly used it and that's why it looks as good as new. But he didn't seem to know much about radios at all.
     
  4. nickr

    nickr Member

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    TGM module is still there.
     

    Attached Files:

    Tokin and Shadetree Mechanic like this.
  5. nickr

    nickr Member

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    Those 2 red square and rectangular pieces of cardboard (on the first photo)were loose in the back of the radio, the square one is glued back on, but the other one is just placed into position for the photo as I'm not exactly sure where it's meant to go. They look like heat sinks to me. Should they both be covered? Anyway, here's the other side of the board.
     

    Attached Files:

    #5 nickr, Nov 17, 2020
    Last edited: Nov 17, 2020
  6. nickr

    nickr Member

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  7. nickr

    nickr Member

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    The radio does something else quite strange too. When I switch it off for a while, it comes back on at 27.0000 Mhz. Seems to only do this when it's been switched off for an hour or so, otherwise it remembers which frequency it was on. I changed the jumper to give a 5Khz step because I was having trouble getting the zero frequencies. [J1on, J2off, J3on, J4off]

    I can't verify the power output at the moment either. My simple SWR/power meter is telling me about 20 watts on SSB, less than 20 on AM and and maybe a bit more on FM. This is in conflict with what the power meter on the radio is saying. That's just checking it with an antenna and not a dummy load.
     
    #7 nickr, Nov 17, 2020
    Last edited: Nov 17, 2020
  8. nickr

    nickr Member

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    http://www.servicedocs.com/ARTIKELEN/14300226290001.PDF

    Have a look at that please. It seems that some were made with fixed power and some were variable. Looking at the picture of my PCB I have the diode mentioned in the document.

    copied and pasted from the document. :- December 2004 there were different versions in the market. Some are 40W FM/AM and others have variable power in FM/AM ( max 25W). If you have the variable one and you want to operate with 40 watt FM/AM you have to add diode D506 = 1N4148 on the print board.
     
  9. Handy Andy

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

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    You have done your research! (Thank you - makes it easier)

    The 40W versus 25W - you want to run 40W mode?

    IF you do, this is why the Diode is in place.

    Why Doesn't it affect SSB power?

    Because of how the Diode - operating as a one way valve - does not allow nearly 1/2 of the audio power envelope to be used as a means to "sample and smooth" - think of this as an NPC mod, but you do this to the limiter.

    Why does it affect SSB? Because of the Radio Design, the methods used to limit Audio envelope - uses the RF power knob - much like a Mic Gain, but it's not controlling Mic gain, your audio - just affecting (attenuating) the audio AFTER all the effects have been applied - to the RF signal now attenuated to a low level signal sample.

    When you Run 40 watts, the ALC/AMC and any other limiter effect needs to be kept in proportion to the level of signal you wish to control - which is why I have to issue to you, that cautionary statement of shortened lifespan. A high SWR, poor power supply - and thermal considerations (Those Bipolars are not bulletproof) the hi-po setting will take it's toll on your system. They, didn't put that in like you'd see in Galaxy class radio chassis - like the 959
    upload_2020-11-17_8-19-17.png
    One on Left is Magnums' but FEEDS into it...not adjustable...in this method.
    On the Right, Is Galaxy, using two methods directly applied.
    Both "sample" and control envelope - one is done by MODE
    the other is done by adjusting Drive thru knob directly.
    In SSB mode, the above left option you HAVE to use Mic gain.
    In SSB mode on the Right- you control the drive used to limit Power on the RF knob.
    These methods are different per function as similar but wiring is different.​

    You just bought the thing - so why not run it safely for a least a day or two while you sort out the functions you wish to keep and others you may need to work on...read on...

    So you either run the 25 Watts - and save the radio for your enjoyment - or run the radio in this Hi-Power Mode and possibly shorten the life of this radio - if you use the 1969 BIPOLAR finals - they don't make these as OEM's (Original Equipment Manufacturer Mitsubishi) so repair options become more limited to MOSFET replacements.
    As far as the "red "squares" goes...
    upload_2020-11-17_8-1-23.png
    Not too worry, you're fine.
    The metal Plate one protects and shields a specific "VCO and TUNING" area from noise that can affect its operation.

    The Red squares are other SENSITIVE areas that need to be kept isolatedisolated from the rear case panels - potential shorts can occur in these areas that can ruin the radio - it is to prevent a vibration from the mobiles setups that can force the cover plates to be too close for clearance.

    Note the lower right one is protecting the IF/TX RF strip and also has a shield plate for this same reason.
     
    #9 Handy Andy, Nov 17, 2020
    Last edited: Nov 17, 2020
    Shadetree Mechanic and nickr like this.
  10. Handy Andy

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

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    As far as the "nickels versus the Dimes" issue, that may be more of an age related problem. Per "oh hey, this may need to be thought out - but RF Limited is knocking on our door..."

    The MCU board, that displays the frequency, also controls serial data the it communicates to the PLL chip by. So due to the nature of the jumpers, the PLL VCO and the MCU may have contention issues regarding DEFAULT settings that are not properly setup - this is a programming issue, not your fault or even the design. It' is simply the PLL's "default" when powered down, is rebooting but the serial data needed to "update" the way it uses the nickels versus the dimes, is has, to be reloaded every time - so they use the nickel default not the dime default - so it instead "boots" thru jumper setting to set default dimes at 27.MHz flat. A programming issue.

    Might need to think about recapping or modifying the power feeds - I'll have to let you decipher that approach.
     
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  11. nickr

    nickr Member

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    Thank you very much for that reply! I have no intention of turning the power up, quite opposite actually. I wanted to be able to limit the power to 20 watts on SSB for my amp. I did see RF Limited's answer to turning the power down using the mic gain. Would it be safe to say that I have the low power version of the S-9 then? I have checked the power using my swr/power meter but it's in conflict to what the radio meter is saying. SWR/Power meter is saying about 20 watts connected to my antenna (no dummy load), the radio meter is showing more than that.
     

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