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Magnum s9 1969 final version

Discussion in 'General CB Services Discussion' started by radioman24, May 18, 2010.

  1. radioman24

    radioman24 Active Member

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    Okay a friend of mine up in vegas runs a magnum s9 with the 1969 finals in it and man oh man does it sound AWESOME!! so i go to look to buy one and all i can find is the mosfet final version witch after owning a galaxy dx98vhp that had mosfets in the amp and in the radio i told myself no more mosfet radio's that radio blew up on my 3 times and the third time smoke was just pouring out, so is a mosfet magnum s9 safe to use? or should i hunt down a 1969 final version of the radio? also where can i find one?


     

  2. Robb

    Robb Yup

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    Only if used. The 1969's as you may know aren't being mfd any more. Nothing wrong with MOSFET's; the problem with them is that people often turn them up too high to get all of the available wattage out of them. Basically just pushing them too far. I run radios with MOSFETs all of the time; but I keep the output 20-30% of it potential. Works for me.

    Another thing about MOSFETS as explained to me by Sam Lewis - who is the mfr of the EKL brand of MOSFETs. Grounding the radio equipment is essential - as well as a proper 1.5 to 1 or less SWR. MOSFET's are susceptible to static damage when handling them - but will run until they explode when pushed into doing so.
     
  3. The Jerk

    The Jerk Active Member

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    I have several years on a Galaxy DX959 with a mosfet, its served me very well. I was "warned" about mosfets, and a little apprehensive about them at first; but I would not hesitate to buy one now.

    The DX959 was set up by DTB, and gets good reports. A lot of a radio's performance comes from the person doing the tuning...that can make or break a radio, and has more to do with their performance and life expectancy than anything else.
     
  4. mackmobile43

    mackmobile43 Jock Supporter

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    So I shouldn't buy one from Quackshack?
     
  5. The Jerk

    The Jerk Active Member

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    That place is still around??? I haven't been there in a long time.
     
  6. davegrantsr

    davegrantsr Active Member

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    so radioman, you should buy the S9-175 with mosfets to get all that high power, run it at 20% output, or 35 watts or so, to protect it. makes about as much sense as buying a motorcycle to use during the winter in nome. please, stab me in the eye with a rubber-duckie antenna. somebody. anybody?

    many, not all, but MANY mosfet CB's that use sideband have a detectable flaw in the audio. audio and/or rf power mods to them just enhance that flaw. sometimes. luck of the draw, maybe? the mosfet cb's are nothing more then a transistor amplifier section that was modified to accept mosfets. true HF rigs running mosfets were designed around the mosfets.

    grounding is as essential in a mosfet radio as a transistor radio. or not. 1.5:1 swr or 2:1 or 3:1 or 4:1 or 1.01:1, with a couple mosfets, or couple 1969's, has the same effect. loss of output. my brother ripped off 1 of his mirror mounts and used his mosfet galaxy across country, and knowing him, non-stop talking for those 3 months, returning for me to replace 1 antenna....and the radio is none the worse for wear. he actually did that with a dx350 once. while the inside was black and toasty, it still worked just fine.
     
  7. 9C1Driver

    9C1Driver Sr. Member

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    Just trying to understand this. So you run your Omega Force at say 10-15 watts PEP all the time? That would be about 20-30% of what it can do. That seems kinda pointless. I run a Magnum 257 all the time at about 45 watts PEP on SSB and it works fine.
     
  8. davegrantsr

    davegrantsr Active Member

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    the point i was making in my post prior to yours. i'm still waiting for somebody to tell me that this is all a sick joke & tech 808 actually took over wwrf. if people would actually read what they write before they post......or just avoid the post altogether.....
     
  9. Cityboy

    Cityboy Active Member

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    Mosfets are very sensitive to heat and high swr's much more so than the silicon based 1969,2166,2132 and will not tolerate running them very long when they are above 2-2.5. The best case is to run the radio with swrs at 1.7 or less and have the proper gauge wire and power supply feeding the unit. Using these radios in a mobile set-up requires you to be very careful and mindful of your antenna situation. Mosfets were mainly created for the home audio use for thier extreme gain and if you look at a home audio receiver it is ventilated and with large heat sink areas; as with cbs that have small cabinets and almost no ventilation holes.
     
  10. dudmuck

    dudmuck Active Member

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    Mosfets are silicon based.
    The 1969,2166,2132 you refer to are bipolar transistors.

    Mosfets have the opposite temperature coefficient compared to bipolars.

    In the context of EKL, you are referring to IRF520 which is not intended to be used for RF power.
    But there are mosfets designed specifically for use with RF power, but they are not in TO-220 package. Because this is a stupid package for RF power.

    Instead of penny pinching, I dont know why they cant use something good like SD1275-01 or MRF455, just need to concern with protecting modulation transformer.

    Its not the final in radio that makes it sound good, its the correct design and tuning of the radio.
     
  11. Cityboy

    Cityboy Active Member

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    dudmuck I stand corrected and the above transistors are silicon based and the 1969,2166,2132 are bi-polars but are silicon based as I stated. The issue was heat and what I stated was true, and the IRF520 may not have be designed for rf power stages but they are using them and they will continue to do so because of the cheap cost of the product.
     

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