RFX-75 mod

Discussion in 'CB Radio Forum' started by DLW3, Nov 25, 2009.

  1. Turbo-T

    Turbo-T Road Train Member

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    May 31, 2009
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    So no one is really doing the RFX75 mods anymore??????
     
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  3. vintech

    vintech Light Load Member

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    May 30, 2010
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    It's amazing to me that the only person that can get 110 watts out of an RFX75 is some tech at a CB shop that got all his training off the internet on how to install it.. I have been repairing Citizen Band for 43 years made a real good living off it and did it by telling the truth.. Truth is a RDX75 on a Cobra 29 will do around 45 maybe 50 and that's only if the tech doing it knows what really must be done to get it otherwise most of the RFX's I seen on my bench where struggling to show 30 watts of true RMS power which is fine it does make a difference, just be honest about it.. In defense of the CB techs you will run into it's most likely they grew up with all the exaggerated claims of every possible kind and it made it tough for a while to be honest. And I do the RFX75 if that is what they want I just tell it like it is and as far as what I charge, Well If you believe what you do isn't worth much it usually reflects in what you charge as well as what you do I don't apologize for what I charge because I never have to apologize for the work I do.. I don't make judgments on what anyone charges if the customer is willing to pay the price and they are happy with the work then it was worth it..
     
  4. IDIeselman

    IDIeselman Light Load Member

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    Feb 23, 2011
    Ludington on the Lake
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    RFX75 struggling to show 30 watts??? You either need a new bench or a new line of work. That is all.
     
  5. vintech

    vintech Light Load Member

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    Well my dear friend for those of us that have dedicated our lives to this business and take great pride in what we do it's all in a days work to get the kind of comments you have just posted. If I had a dollar for every driver that came in telling me the shop he had his Cobra 29 to told him it was doing 45 watts and that's without the RFX75, Well I would be much richer, But it changes nothing The RfX75 is utilizing 1 ERF2030 Mosfet Driving 1 ERF7530 together the rated output at 13.8 volts on the Drains is 50 watts RMS power but only if the circuit is running at 100% efficiency and I promise you no amp circuits do that, The PEP Envelope on the data sheet is only 75 watts PEP for the ERF7530 the only reason you get those crazy readings is because of the FEEL GOOD METERs shops use if they yell or whistle these meters will show a stock cobra 29 doing 25 watts. No, I'm sorry but the best you will ever see in most expensive amps of this kind is maybe 70+% efficiency and that don't come anywhere near 110 watts. So you can say what you want, think what you want, but if you believe the shop that told you it's doing 110 watts, Wellllll that is certainly your business. This reminds me of the man that had a antenna problem in his mobile he was running a 4000 watt amp and his bird meter was showing 5000 watts but his reverse meter was showing 1000 watts reflected power. Well naturally I told him several times that it just wasn't right. So he came and we checked it out found the antenna was showing 3 to 1 swr's we fixed it and it was around 1.2 when I was done. So he fired it up and the Bird meter was only showing 4000+ and he was mad. I actually had to reset the antenna to 3 to 1 so the meter would show 5000 again before he was happy.. when you have that much reflected power the meter adds the reflected power to the forward power and gives you the high reading it happens allot more than you would think, out there in CB land... But no hard feelings ...
     
    trees Thanks this.
  6. IDIeselman

    IDIeselman Light Load Member

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    Ludington on the Lake
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    Alright, I was going to keep quiet but, I failed miserably. Could you please explain to me the final section utilized and the output of a Magnum 257HP 10 Meter Radio.
     
  7. vintech

    vintech Light Load Member

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    Well I'm not sure what you mean but there is no difference the M257HP is a radio with an RFX75 on it. You will be very hard pressed to see one review on Youtube or anywhere else that gives this radio more than a 75 watt peak reading and if you remember the true RMS will most often be only half that you have a real RMS of maybe 40 watts . You must remember it's the old saying all over again "You can't get blood out of Turnip ". Peak readings mean something but more an indication of audio power not an indication of RF Power. And the Dozy, Astatic, Paradynamics Meters most shops use add to the problem because they don't use real peak reading circuits it's just a capacitor used to increase the swing and on top of that these meters use meter movements that have no damping which means when you talk or whistle the meter will swing wildly past the point of accuracy. If the radio will deadkey 110 then you have something but then it should show nearly 200 on peak readings.
     
    trees and theakerstwo Thank this.
  8. EZ Money

    EZ Money Road Train Member

    Good info vintech!
     
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