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    The 10 meters 27MHz CW radio amplifier is equiped with VN66AF transistor produced by Siliconix wich has some advantages: its cheap, great dielectric insulation and high gain. Here we use VN66AF as an rf amplifier for 10m band (26 … 30 MHz ).

    With this 27MHz rf amplifier, small transmitters ~ 200mW, can be transformed in 2 to 3 W 10m transmitters. The band-pass filter attenuates at least 55dB.
    For linear applications (AM and BLU) the VMOS FET gate current has to be 20mA adjusted with P1. If we want to use this 10m rf amplifier for FM and CW adjust P1 so there is no current to FET gate. In our case the repose current ( steady current ) is 200mA to 300mA.

    VN66AF amplifier circuit components

    L1 = 12 turns / 0.6mm / 9mm
    L2 = L4 = 5 turns / 1mm / 9mm
    L3 = 8 turns / 1mm / 9mm

    VN66AF 10 meter CW amplifier circuit schematic

    10 meters rf amplifier schematic

    VN66AF pcb layout

    10-meters-rf-amplifier-pcb

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    9 Responses to "27MHz CB Amplifier Circuit"

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    1. VN66af for Q1 cant be had anymore. I built this with a mosfet irf710 that I had laying around. Get nothing for gain, that is, unless I do away with the input coupling capacitor, which is C1. Then I get a real good noisy handheld CB and a little output. It just does not work.
      I found another schematic based on this circuit. The Datasheet for the VN66AF shows a test circuit that looks a little like the schematic here accept it has more components. Looks more stable.

      Does anyone know of a real, working cross to the Q1? I assume it is a mosfet, but I am not sure what mosfet would work. No cross.

    2. uh mosfet says: on January 10, 2009 at 1:07 pm

      Uh, anyone know about the vn66 ? What does it cross too. Nothing? So this circuit is a fleatingwangdownersleak…

    3. Some wanker on ebay has one for 36 bucks… crazy wanker

    4. Hey, Id say forget about this circuit, there is a another one out there you can build with the mosfet irf840. Author claims good watts very comparable to this circuit. Forget the chumps who sell old obsolete parts for 40 bucks for one, pathetic little mosfet.
      By the way, its a vmos. Supposedly better in some cases, research it on wiki. Very interesting.

    5. Electrolover, Sorry for the rudeness. I built this and tried it with irf840, irf 710 and irf740. I’m not really sure how to get it going with those fets. When I couple one of the coils and the gate I get some strong radio signals but only when a 3 foot wire is attached to out put while under 50 ohm losd. With out that there is nothing.

      I will try to post the other, but if you google irf840 linear, you will get it number one.

    6. Dear Sir:
      When I bought 2XAA35MHz remote control cars, remote control
      Distance, only 4.5 feet, very short, I would like to add 12 feet, can you add more than VN66AF amplifier, I do not know, please advice, thank you

    7. I have VN66AF’s, will part with them for $6.00 dollars plus shipping and hanlding.

    8. sir
      10m cw amplifier 1—-transistor vn66af equivalent japanese transistor?
      2—-coil wire gag number 06mm dia.and wire number pls?

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