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What power supply

Discussion in 'General CB Services Discussion' started by 3puttbob, Jan 2, 2013.

  1. 3puttbob

    3puttbob Member

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    Hi All
    I want to use my 500 watt polomar amp on my base station (Cobra 2000). Basic math shows a 50amp power converter is what I need. Anyone have suggestions as to what power supply? Would a battery charger work(sounds real hillbilly, I know)? I have a nice 120v tube amp now, just wondered how well the 12v amps work.


     

  2. Ratfink

    Ratfink Active Member

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    I would stay away from a battery charger. It never hurt to buy more than what you see amperage wise. Adjustable voltage is nice but not a have to option. Astron makes nice supply's I've had mine for many years and no problems.
     
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  3. vo1ks

    vo1ks Active Member

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    When I calculate power supply load, I assume the amplifier is 50% efficient. This is a reasonable starting point for most, although class A can be as low as 10%. For 500 watts output, you will need 1000 watts input.
    At 12VDC that would be 1000/12 = 83 amps.

    A deep cycle battery with a float charger could serve you well.
     
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  4. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    Warren is right (VO1KS). Most people never take into account the efficiency of an amp or radio when trying to calculate the current requirements. All that heat generated by the radio/amp has to come from somewhere and it ultimately comes from the power supply.
     
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  5. 9C1Driver

    9C1Driver Sr. Member

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    Instead of saying "500 watt Palomar". tell us the model number and what finals it has? To get 500 out of a Palomar I assume it's a 1x4, let us know. This will help pin the amp draw down better.
     
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  6. TonyV225

    TonyV225 W9WDX Amateur Radio Club Member

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    I would say get yourself a 70 Amp Astron power supply. Although as stated above it would be of more help to know what transistors the amplifier is running because we all know how the model number and actual power output differs from what most people think or expect to see.

    With knowing the transistors that are used in the amplifier in question is using its the easiest way to know what PEP output truly is thus knowing what amperage is required.
     
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  7. XXX

    XXX Active Member

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    I use a astron plane jane 50 amp.. plenty of nutz .. I believe the 50 amp is a continuous rating .. I know guys using deepcycle marine batteries and battery chargers and they say its the only way to go.. they cut charger when on air ... no 60 cycle noise here .. xxx
     
  8. Ranch55

    Ranch55 Active Member

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    I have been running two of the MFJ 75A power supplies for a year now and they both have performed quite well. The most I have used with them are Texas Star 500V amps that have been tuned up and transistors changed to Toshiba 2SC2879 non-dots. The amps will do 600 watts plus PEP on the MFJ power supplies. No problems encountered at all.
     
  9. XXX

    XXX Active Member

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    HAVE YOU TALKED TO ANY INTELLIGENT LIFE FORMS ON THESE SOPHISTICATED COMMUNICATION DEVICES ??? NICE GEAR INDEED !!! XXX
     
  10. Ranch55

    Ranch55 Active Member

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    Some folks do not have any intelligent replies or offers of help. Such narrow minded people usually are so opinionated they have only one view point and all others that do not agree with them are not subject to be listened to.
    So, these are the ones to avoid and not listen to. They are "know-it-alls" and actually know very little, which is divulged by their unintelligeable and immature comments.
     
  11. XXX

    XXX Active Member

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    I REPRESENT THAT !!!! XXX
     
  12. BBB

    BBB Well-Known Member

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    No. The Astron 50 amp supply is only rated for 37 amps continuous. http://www.universal-radio.com/catalog/hamps/1815.html

    The general rule is that 20 amps are needed for each 2sc2879 device. Example: a (4) pill Toshiba 2879 box would require an 80 amp continuous duty rated DC power supply. Don't overlook proper wire sizing to handle the large amperage draw. A 10 gauge wire isn't going to cut it in this case.

    These are the hidden costs of $olid $tate linear amplifier ownership ;)
     
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  13. 543_Dallas

    543_Dallas Sr. Member

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    Definitely hidden costs that some overlook. I like overkill when it comes to power supplies. The use of old server power supplies really cuts the cost down though. Most guys I suggest this to don't want something that doesn't come in a nice case ready to sit on the desk.
     
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  14. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    Try not to represent that in the future please.
     
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  15. 222DBFL

    222DBFL Sr. Member

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    I would look at the MegaWatt 50A power supplies. 2 of them can be run in parallel out of the box with the voltage adjustments. And they are well made power supplies!! Also they are a site sponsor. Good power supply for the money at $110 each for a 50 amp power supply that can be run in parallel. JMHO.
     

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