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Illegal high power HF amplifiers

Discussion in 'Amateur Radio Amplifiers' started by N8FVJ, May 20, 2019.

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  1. N8FVJ

    N8FVJ Ham Member QRZ Page

    I wonder how many hams violate the FCC power limit. I know some must do it and likely show up on 75 & 40 meters. Perhaps they were power hungry CBers that got a ham license. Most antennas are rated 2KW such as the EFHW-8010-2K with a balun. I assume a wire antenna without a balun must be used with RG-17A coax.

    You think a 4CX5000A is used? Also a 3CX3000A7 that is way less expensive vs a 8877 will produce at least 5000 watts. Reason is about ten 4CX5000 and 3CX3000 are for sale on ebay and ebay does not normally sell to radio stations. So, someone is buying these tubes.

    I think a 4CX500oA would make 7500 watts output using a 60 amp 240 volt AC input. A cheap 'pole pig' transformer would power the amp.

    Note- I do not condone illegal power.
    Last edited: May 20, 2019
    PU2OZT and KU3X like this.
  2. K9STH

    K9STH Ham Member QRZ Page

    I knew an operator who had 4-1000-tubes in the driver stage of his linear amplifiers. He was technically a moron but paid people to work on the equipment. This person established a contest station here in Dallas, Texas. One day, he decided to work on one of the amplifiers with the power on. He got his arm across the B+ and the arm was literally blown apart. He died the next day.

    Although I am an advocate of running higher power, the legal limit IS the highest power that any amateur radio operator should run. Anything beyond that level is a big NO NO as far as I am concerned!

    My main amplifier cannot quite make it to 1500-watts. The highest power that I can get is about 1400-watts. My other amplifiers can make 600-watts, 600-watts, and 850-watts output. I am slowly building an amplifier that uses a pair of the Russian GS-31b tubes. It will be capable of making over 1500-watts. But, 1500-watts is plenty and I do not plan on ever running more output.

    Years ago, here at the "new" Collins Radio corporate headquarters in Richardson, Texas, the 3 MHz to 30 MHz log periodic antennas were being manufactured. Each had to be tested over the entire range at powers up to at least 20,000-watts. The Collins technicians were authorized to operate on any frequency within that range. For testing a KWM-2A fed a 308-U20 amplifier putting out at least 20,000-watts. With the antenna gain, the e.r.p. was about 200,000-watts.

    One of the favorite test frequencies was CB Channel 19! The technicians would make a test transmission and then sit back and wait for the chaos that would happen on the frequency. Then, to stir the pot, they would make several more transmissions never acknowledging any station trying to make contact.

    Glen, K9STH
    PU2OZT, N7RMZ, N1EN and 5 others like this.
  3. KU3X

    KU3X Ham Member QRZ Page

    It's a sad state of affairs when someone cheats in a contest and runs 10 KW to have a higher standing. Would that same person enter a foot race, half way through the race jump in a car and then be dropped of 2 blocks from where the race ends? What's the difference. A cheat is a cheat !
    Next they say, "but I need head room !" How much head room is needed when you purchase or build an amp that is designed to run at 8 KW out?
    6500 head room? Really ?
    I build my own amps. Both of my in service amps are designed to handle 2 KW. I've tested them honest dummy load. Now I know they will handle 1500 watts out all day long , if needed.

    If you have to cheat to accomplish a task, what did you prove?

    Barry, KU3X
    K6EFA, KK9W, AB2YC and 10 others like this.
  4. KD2ACO

    KD2ACO Platinum Subscriber Platinum Subscriber Life Member QRZ Page

    If an amateur can't make the contact at 1500W, the propagation isn't good or the antenna isn't good.
    N8ZL, PU2OZT, KK9W and 7 others like this.
  5. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I don't think many amateurs exceed the legal limit output power. A very small percentage might.

    I have a homebrew 4-1000A amp that can reach about 2.2 kW output power but ran that for one "test" back in 1984 when I built it and never drove it that hard again, even once; it's an AB1 amp (grid-driven) and at legal limit power with proper loading the grid and screen currents are about zero. No real difference from 1.5kW (1.7 dB), nobody'd even notice it unless it was an e.m.e. contact or something.

    My old Henry 4K Ultra could exceed 2kW output also (8877) but I never did that, either.:p
  6. KA8NCR

    KA8NCR Ham Member QRZ Page

    There has to be thousands of those things sitting around the country. No guess to as how many of them actually work.

    Here is the real deal.
    K6LPM likes this.
  7. WG7X

    WG7X Platinum Subscriber Platinum Subscriber QRZ Page

    I’m with Steve on this one. I like to think that most of us who have amps use them in a safe and legal manner.

    My amp, an AL-82, makes just about 1.5 kw on most bands, a little more on some, a little less on others. I’ve read posts about this amp beI got capable of as much as 2.2 kw. I’ve never seen anywhere near that and if others have actually achieved that they are either using a lot more drive than I am or have a metering error or both!

    Probably both...
    KD2ACO likes this.
  8. N7WR

    N7WR Premium Subscriber QRZ Page

    In the past I have owned several amps capable of exceeding 1.5 K.....but I also had an accurate watt meter and never drove those amps beyond the legal limit. The responsibility to obey the regulations rest with the operator. I once operated from another ham's station who told me everything was tuned up and ready to go on 20 meters. Yes it was except until I reduced the drive to the amp the amp was outputting about 1700 watts. Cheating is not my style.

    As for antennas many commercially made HF antennas are rated for 3 KW and some for 5KW
    K4AGO and KU3X like this.
  9. WA4SIX

    WA4SIX Ham Member QRZ Page

    Sure. Has to be the damn CBers.....
    Do you know that it has been going on way before there were solid state amps? Even before September 11, 1958?
    Also, for anyone with a high power amp, they will not run an EFHW-8010-2K
    I look at this as a pitiful troll post.

    Of course, it's just so much fun to blame CBers....

    Last edited: May 20, 2019
    N4CKC, K7MH, KM1H and 3 others like this.
  10. WA4SIX

    WA4SIX Ham Member QRZ Page

    Oh, even as a Cber, I never ran over 1.5KW on air.

    N7TH, KM1H, KK5JY and 4 others like this.
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