24 Pill Amplifier

Discussion in 'Technical' started by WD5JKO, Aug 30, 2015.

  1. WD5JKO

    WD5JKO Member

    The following You Tube video demonstrates the insane level of sophistication that is going into some illegal 11 meter CB radio amplifiers.

    I am not advocating that we all get on CB with a 5 KW rig, but to instead dissect from this any good ideas that might exist and be applicable to AM ham radio.

    Some things that caught my eye, and ears from this video:

    ** They use that term RMS power as read on a Bird wattmeter ;)

    ** Looking at the bird on PEP while speaking is clearly overdriving the amplifier such that the modulated waveform positive peaks are clipping. The ratio of carrier power (they say RMS) to PEP appears to be around 10X.

    ** I think some of the power layout, cooling, B+ decoupling, ideas are fairly well thought out.

    Imagine what that kind of power would do in a mobile installation. I can visualize a lot of carnage in automotive electronics, and perhaps life ending RF burns should anyone get close enough to the antenna. Also, the electric and magnetic field strength near human tissue will certainly cause warming.

  2. W5HRO

    W5HRO Administrator

    You cannot tell by looking, but the guy must have the peak reading kits added to the Bird 43 meters. There was/is an add-on kit for those. The problem is those kits are not accurate and especially on AM. Either that or he has his CB and everything detuned so it will do that, but it's still not real. Bird did finally come out with another model a few years ago that is fairly accurate, but the 43's with the peak kits are not.

    Anyway, it makes you wonder… are there really guys like that still on the CB band? I thought the CB band here in the U.S. had pretty much died down to almost no activity except for truck drivers on channel 19 and then those black guys (gars) with the huge amps who get on there during the skip cycles and ghost talk. I turned my NC-303 receiver there last winter and that's all I heard. I also meet up with an old 1970's radio friend of mine for dinner during our recent trip to Tulsa, KB5SNZ and he said the last time he turned on his old Uniden 10/11-meter radio that's all he heard were truck drivers on channel 19 and one more person on one of the other channels, but everything else was completely dead. I use to work on his CB stuff back then and then sometime in the late 80's or early 90's I helped him get his ham ticket when we reconnected.

    KB5SNZ on the left, me W5HRO on the right
  3. W5HRO

    W5HRO Administrator

    By the way here is one of those crappy peak reading kits below for the Bird 43 to make it a 43P. All it will do though is make it a BS power reading meter. They are NOT accurate, but great for CB'ers and dumbed-down newbe type hams who want to see that swing :icon_lolno: They will work better for tuning a linear on SSB, but they are still not accurate.

    Not only that, but it's for trying to make it read Peak power and not PEP power.


    The only meter Bird makes that actually works good is the APM-16 Mean/Avg power meter below. These are accurate. The only problem is they are around $1000 each. Just use one of these if you can afford it and tune for the 1500 watts max with modulation on AM or SSB and forget about trying to measure PEP. It's almost impossible using an analog or digital meter to measure PEP and it's insignificant anyway. Be smarter than the FCC was back in the 80's when they screwed everything up with an unrealistic power measurement goal.


    Anyway, what the guy's video is showing is complete BS and not real.

    Attached Files:

  4. KB3ZUW

    KB3ZUW Member

    That's a very nice Bird meter. Didn't know they existed. I see those meters can be had for under $300 used, but the elements for use in the HF spectrum cost just as much as the used meter.

    Maybe I'll pick up a used APM-16 meter for $225 and keep my eye to the curb for some 2-30MHz elements. Thanks for the tip.
  5. W5EFR

    W5EFR Member

    Yes, there are still guys like that on CB/11 meters...

    Take a listen on Channel 6, those guys take turns "dropping the Maul" on each other from across the country. Big AM power, 90% pinched/overdriven Audio, 9% decent audio, and 1% of the ops are running outstanding, asymmetric modulated audio... Tube amplifiers, and a few Solid State amps as well.

    The guys running the Hi-Fi audio are the ones that know what they are doing and do not bleed over, the others are 3 channels wide half way across the country from the splatter.