Another Homebrew transmitter is being saved.

Discussion in 'Amplitude Modulation' started by N6YW, Feb 24, 2017.

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  1. N2EY

    N2EY Premium Subscriber QRZ Page

    CCS ratings, natural cooling.....long life......Need about 30 watts of drive, plus circuit losses and headroom.

    IIRC, this means the same 2500 volt supply can power both the final and the modulator, if you so desire.

    And no need for a screen choke or tertiary winding on the mod iron.

    And if you get the right transfomers......a Peerless feeling....

    Yes it is.......but be warned. It can ruin you for manufactured stuff.

    73 es TNX de Jim, N2EY
    N6YW likes this.
  2. N6YW

    N6YW Ham Member Volunteer Moderator QRZ Page

    Never! but I know what you mean.
    Oh yeah, rolling my own is nothing new to me, in that I have built well over 100 guitar amplifiers
    and numerous other projects relating to the recording studio and 1000's of repairs.
    I will have a lot of fun doing this one because I get to dictate from the very start on the build quality
    and placement of critical components. The early layout design is going to be so very important as
    to help resist problems down the line. Having to re-do and re-arrange something just to keep
    it operating properly is not what I want to entertain.
    Speaking of which, I am curious as to anybody else's layout ideas with regards to lead dress and
    routing of metering lines, high voltage leads etc. I find it interesting of what others use as rules
    when building. It's a fascinating subject.
  3. K4KYV

    K4KYV Premium Subscriber QRZ Page

    I pretty much run all my stuff at CCS. Tubes are getting too scarce and hard to come by.

    Unless you want to modulate the driver along with the final, as in the Gates. Then the tertiary winding may be useful. Even with plenty of grid drive, it probably increases modulation linearity. Modulation linearity, as indicated by the trapezoid pattern on a scope, is something I pay a lot of attention to. Some tubes will make full power, but with the sides of the triangle on the trapezoid pattern curved. If there is significant curvature and I can't adjust it out, I label the tube as unsatisfactory. It might be OK for CW, but not AM except maybe in a pinch when a good tube is not available. Besides loss of headroom on positive peaks, non-linearity produces unnecessary signal bandwidth even when the resulting distortion is not audible to the ear.
    N6YW and N2EY like this.

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