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Communications Concepts

Discussion in 'General CB Services Discussion' started by Pman62, Oct 10, 2018.

  1. Pman62

    Pman62 Member

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    Anyone here ever hear of, or deal with Communications Concepts Inc. ? I was looking at one of their linears, namely the EB63A 140 watt. It is supposed to produce 140 watts with a freq response of 2-30 MHZ and can supposedly handle up to 5 watts of driving power. It will handle AM or SSB without any external switching. All of this is designed for mobile operation. It is a little pricey at $157.85 for a kit. Any thoughts?


     
    #1 Pman62, Oct 10, 2018
    Last edited: Oct 10, 2018

  2. nomadradio

    nomadradio Analog Retentive

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    They are an odd outfit. Reportedly they are legal to sell ham linears that don't strictly meet the rules for a ham linear.

    Might just Google them for a better picture. Never really looked into it.

    They have been around a long time, so it should be safe enough to do business with them.

    When they quote you a drive-power limit, it usually means peak drive power, like for SSB or CW. That 5-Watt number probably does not mean AM-carrier power.

    Only hams have radios with only 5 Watts PEP.

    Your stock out-of-the-box Cobra 19 should deliver around 16 Watts PEP.

    73
     
  3. nomadradio

    nomadradio Analog Retentive

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    Here is a link to the thing.

    http://www.communication-concepts.com/eb63a-140w-hf-amplifier/


    Pretty sure I'm right about a bone-stock CB overdriving it by a margin of three-to-one or more.

    It's a kit to build the circuit board alone.

    No heat sink.

    No enclosure.

    No connectors, power switch, pilot LEDs, etc.

    Does have a nice, big relay on the board.

    73
     
  4. Pman62

    Pman62 Member

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    I originally saw the schematic for this amp in a book named "Circuit Encyclopedia and Troubleshooting Guide." In the description, it said that " both the parts and kits for this amplifier are available from: Communications Concepts....." The copy write date for this book is 1993, so I was actually kind of surprised that the company was still in business when I did a google search for them. Yeah, I think this is kind of pricey for Not getting an enclosure, or connectors, ect. I was wondering about the drive power and figure that in AM mode a stock CB would probably be OK, but on SSB.... probably not.
     
  5. nomadradio

    nomadradio Analog Retentive

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    Designed to be clean, not cheap.

    To be a legal ham linear, it would still need a low-pass filter behind it for the band you're using.

    The low-pass filtering and the band-switching that select the correct filter cost money. This is a lot of the higher cost-per-Watt you pay for a legal ham linear.

    The illicit 11-meter boxes leaves all that stuff out. Does cut the cost of production in a big way.

    73
     
  6. kopcicle

    kopcicle Sr. Member

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    Odd how these subjects come up. I was just discussing this with someone earlier today that should know better than to answer the phone when I call . Refer to AN762.pdf for all but the MRF454. The mathematics are clearly discussed in AN779.pdf for plastic TO220 transistors but the principals still hold for anything from a 2SC2166 to a 2SC2879. I've supped 2SC2166/2SC1969 into the AN779 design with little effort.
    I don't have the details for the MRF454 anymore but I did the math and applied it to a bare bones 2 transistor amp with predictable results.

    Bias adjustment is critical to linearity and the lifespan of the transistor. Deviate from the spec at your own risk or a quality test fixture.

    Nomad is correct, no matter what the white paper seems to say. Biased "on" to AB the MRF454 IS VERY SENSITIVE TO DRIVE. It's something to be whispered at , not hit with a hammer. I learned the hard way and ended up using a 5db input pad as well as making sure AMC and ALC were in place and verified to be working. ALC overshoot and undershoot is a topic for a very long discussion .

    I just posted this elsewhere today so ... kep2_kicsi-600x600.jpg

    It just "might make it at 3-4 AM and 10w SSB

    s-l1600.jpg
    This absolutely will. That takes care of the input .

    gen2single.jpg

    That takes care of the output.

    The rest of the porn, I mean parts can control boards can be found here .

    https://www.w6pql.com/parts_i_can_provide.htm#23cm

    So where does it stop? Well it starts with a $120 two transistor box and ends up being a 1.8 to 6m piece of technological coin. Getting close to $600...

    or

    wa1gfzclasse.jpg

    Ask me about it sometime...
     

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