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Looking at new amps.

Discussion in 'Amplifiers' started by Grogan, Mar 11, 2016.

  1. Grogan

    Grogan
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    Will the 811H work on Am and SSB. What kind of output would it have on 10 and 11 meters with the optima or with a radio and small driver 80-100 watts.


     

  2. 543_Dallas

    543_Dallas
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    It will work on AM. I don't know what it will do but you'll probably keep the carrier to 150 watts or less and around 600 pep to prevent a melt down. AM operation makes a lot more heat than SSB. Some people upgrade to 572b tubes with more plate dissipation but you'll still have to consider the limitations of the HV transformer. Good plate iron isn't cheap.
     
  3. Crusher

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    LOL, good luck getting 572B's. They are scarce nowadays. It's a long waiting list.
     
  4. Grogan

    Grogan
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    I may just go with The TnT amp from Xforce wondering about the pp100 transistors are the better than DEI will they last I don't plan on driveing it hard.buy don't know anybody running the new amps.
     
  5. 222DBFL

    222DBFL
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    Haven't heard much about the new ones Grogan, but my older one with Toshiba 2879's in it rocks on SSB with the optima mk3. Just keep the input to about 40-50w max pep on SSB and I think you'll be just fine with the new pp100's. As far as them being any good or better than the DEI transistors, only time will tell.
    You might try asking Crusher if he will build you an amp. I'll leave it at that.
    But if you just want an off the shelf amp, the TNT 600 should work with the optima mk3. Just watch the drive levels on SSB. Keep them to about 40-50w pep max. And I think you will be okay. And don't try running it at 17vdc either. Keep it at 13.8-14.2vdc max. JMHO.
     
  6. 1502gulfcoastMS

    1502gulfcoastMS
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    Rf watts divided by DC volts equals DC amps?

    Edit;
    I ask because I have a little home brew 4 pill that does 650 to 750w at 14.0v on a 32 amp regulated power supply. I have had this checked on other stations and PS with same results.
     
    #21 1502gulfcoastMS, Mar 19, 2016
    Last edited: Mar 19, 2016
  7. Justme

    Justme
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    650 to 750 watts on 14 volt and 32 amps?
    14 Volts and 32 amps is 448 watts DC input.......so a magic amp that gets 448 watts DC input and transforms it to 650 -750 watts RF output?

    Lets see, maximum efficiency in Class C is 70% meaning every 100 watt DC input delivers 70 watts RF out, rest is heat, remember those heatsinks are there for a reason?

    14 volt x 32 amps is 448 watts DC INPUT, x 70% efficiency is 313watt RF out.

    Class AB is even less efficient 55 to 65 % depending on the bias you run.

    So recalculating 70 % efficiency for 750 watts RF out is 1075 watts input in DC or at 14 volts 76.4 Amps.

    Dunno what Watt meter you use, but it sure needs some alignment....

    Al calculations above with no losses in the DC wiring that normally is quite severe.
    Meaning the output will be even less as calculated.
     
  8. 1502gulfcoastMS

    1502gulfcoastMS
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    Its a very odd box, I have tested this box on a few different meters, power supplies and antenna. I don't run the box at all just something I got from a flea market. In theory it should not work like it does. I'll have to look to see if I can find that box and post some pictures. I remember there is no name on the pills or could not be read. No names or labels either. It's a very larger box for just 4 pills too. It's just a little bit smaller than a texas star 12 gauge box.
     
  9. Justme

    Justme
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    It doesn't matter what box it is the laws of nature cannot be broken, it cannot simply produce more output in RF as it gets in in DC.

    As stated i didn't even calculate the DC losses in the power supply cable, i bet pulling 30 amps over 3 feet of cable you will see a drop in voltage at the collectors down to 12 to 13 volt max.

    My Heathkit SB 1000 draws 7+ amps max at 230 volts, for 1 KW output.
    That is 1600 + watts input in the amp, where we have the transformer losses, 14 amp at 5 volt heater, and class AB.
    That barely is sufficient to make 1000 watts PEP,
    That is measured by a Daiwa CN 801 active PEP meter which was calibrated.

    Here the capacitors in the power supply can just deliver enough stored power to get it to 1 KW.
    ( Most of the time i run 400 - 800 watts)

    It simply is not possible to get more RF power out as you put in in DC.
    I am a licensed Ham since 1977 building most my own stuff or refurbish older stuff.
    I also repaired lots of CB stuff here including amps.

    There are no magic amps, no magic transistors/fets that deliver power far above their specifications before going bust.
    Most transistors used in CB amps are made for 75 or 100 watts output and used as that will deliver decades of service, with 4 100 watt transistors and losses in couplers you will see 350 -375 watts output safe.
    Yes you can push the envelope to 450 or 500 watts but expect failiures soon.

    My FT 2000 - D runs 4 FET's in the P.A. good for 400+ watts but deliver just 225 watts PEP.
    Yaesu did this for a reason, as do all Ham transceivers that are made this way.
    For that 225 watts my P.A. section is fed with 10 amps at 50 volts or 500 watts input for 225 watts RF out.
    That way tranceivers will still work fine after decades of use, keep the output within specifications and a gaggle of protection circuits.

    There are a lot of bad wattmeters out there, most just do what the average CB person wants to see max smoke, if that is real or just a wrongly adjusted meter is of no concern.

    Measuring PEP in SSB can only be done by a wattmeter with an active circuit measuring and holding the peak power.
    Else without it you just get average power, that is lots lower as the real PEP power.
     
    #24 Justme, Mar 19, 2016
    Last edited: Mar 19, 2016
  10. 1502gulfcoastMS

    1502gulfcoastMS
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    Thanks your input, I do understand I=v/r. I Also know this is not a magical box. I need to find that box and see what's inside. It's a very larger box, not knowing what's inside makes this point moot.

    My shop is fed with 120/240v single phase. I have a box that allows me to run 3 phase equipment @480v. Without you knowing what's in that box, it "breaks the laws of nature" and I can assure you my fluke is just fine and I know how to use it.
     
  11. gameover

    gameover
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    I am perplexed as to how some of these class c amplifiers can put out that much power.... that box must be splattering all over the intended operating frequency.

    My 8 srf3662amplifier does 1000 watts peak. How is your 4 pill making 750w?
     
  12. Justme

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    Quote:
    I ask because I have a little home brew 4 pill that does 650 to 750w at 14.0v on a 32 amp regulated power supply. I have had this checked on other stations and PS with same results.
    Unquote.

    I went in my calculations from your own story..
    So, either you measured wrong, or the Fluke is wrong.
    ;)
     
  13. 222DBFL

    222DBFL
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    Okay we can stop this I beleive with a little bit of true know facts.
    Is it me or did I miss the part in the post above that states by 1502gulfcoastMS, that there is no name or readable print on the transistors. So we don't know what transistors are being used. He also stated the box is very large leading me to believe that there might be some DC to DC conversion in the box and also maybe some different voltage transistors that get have enough DC to DC conversion to only need 32amps to make the 750w that he says it's does. 48vdc or even 24vdc. At 24vdc and 32a, you get 768w. And at 48vdc you get over 1500w of power. So maybe he isn't bs'ing at all. Need to open it up and see what is under the hood. But I have a feeling there is more to it then just a plain old run of the mill 4 transistor amp. Or I could be s total DUMMY and be Wayyy off base here, so don't flame me. Just thinking outside of the box i guess. He did say it was large, odd looking, and there are no labels and no name on it. Post up a few pics if you can please there 1502gulfcoastMS. And oh yes if this amp is using 48vdc transistors that are 50% eff. in class AB bias, then 750w would be about right.
    Or like I said, I am way off here. By no means am I in any way an amplifier expert by any means. Just throwing out some possibilities is all. And they may be totally wrong!! But at least I am trying to wrap my head around it in a different way. At any rate. Good day all!!
     
  14. Justme

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    I don't accuse him of B.S in us, i just questioned the data he posted he fed the amp at 14 volt and 32 amps as he stated himself.

    That leaves 448 watts input, transforming that into 24 or 50 volts is adding more loss to the input power, because voltage transforming circuits also use power.

    For the rest, lets see what is inside, but i went from his own words 14 volt x 32 amps feeding the box.

    1502gulfcoastMS open the box please and show some pictures so we might get some idea's what it is.
     
    #29 Justme, Mar 20, 2016
    Last edited: Mar 20, 2016
    222DBFL likes this.
  15. 1502gulfcoastMS

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    I'm sorry to have have gotten this thread so off topic. Until I find that box and can post some pictures it's all a guess or theories. I never really ran that box because it was so odd.There were some things in there I didn't recognize from other boxes. I understand some of Ohm's law and I know the's is no such thing as magic boxes....
    I will look for that box to post pictures asap.
    Is there a fluke that will measure rf watt?

    I may have measured volts on the line side of a dc to dc xformer. I don't know til I can look in that box
     
    222DBFL likes this.

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