AD6KA’s EB63 (non “A”) amplifier

As I continue working on mine, Ken AD6KA who has also built an EB63, has been kind enough to answer the questions I had regarding this amplifier. Yesterday he sent me a few photos of his original version of the amp so I could compare it with the “A” version I’m building now.

Ken’s amp has seen a much wider variety of service than mine ever will. I’m a CW-only op (and may have to modify the T/R delay accordingly) but Ken uses this amp with a variety of PSK rigs from Small Wonder Labs, his MKARS80, BITX20 and his K2 prior to adding Elecraft’s 100W PA.

Ken’s implementation of both a fan and a heatsink allow higher duty cycle modes than CW.

Here are a few photos of Ken’s amp with the original open-frame relay:


And a low-pass filter kit from K5OOR greatly reduces the size of what I’m planning to build – I may yet switch to this more compact solution:

 My own build is progressing and I’ve found the most only time-consuming part is the drilling of the heatsink. For now, my heatsink is a big slab of heavy steel. If more is required for intermittent CW operation, I’ll have to come up with something more substantial.

Ken also sent me this interesting link of another builder of one of CCI’s amps. This is G3TSO’s description of his project with quite a few add-ons. The beauty of any of these CCI amps is that the builder has a lot of flexibility in the finished product – a utilitarian 100W amp or a jazzed-up version in a housing that matches the other equipment in the shack.

In my case, it’s a learning project of not just the amplifier but my future plans for my own T/R circuitry and various protection circuits that a more expensive solid state amp requires.

Ken, thanks for the photos and for letting me pick your brain a bit!



  2 comments for “AD6KA’s EB63 (non “A”) amplifier

  1. Ken Pendarvis, AD6KA
    March 8, 2012 at 5:34 pm

    Hi John:
    Thanks for kindly posting my EB-63 photos.
    Re the K5OOR Low Pass Filter Board kit:
    After further testing and operation with the EB63 I
    cannot in good conscious recommend it for
    use with the EB63. While it does work, with it’s very
    small and the closely spaced inductors become very hot,
    even when run at low power, even as low as 50w PSK31
    or other continuous duty cycle such as PSK or RTTY.
    With an ICAS duty cycle such as SSB at 100w the LPF board
    inductors become very hot (as in too hot to touch).

    I am looking for other non-homebreew alternatives
    for an HF LPF network but have come up short at this
    point. If I cannot find a preprinted PC board from
    FAR Circuits, I may look for a buddy who has one from
    a parted out commercial HF rig I can canabaliz.
    73, Ken AD6KA

    • March 8, 2012 at 7:57 pm

      Hi Ken – I saw K5OOR’s filter board recommended recently but can’t remember where…perhaps on an eHam forum. I just built my own from various inductors I had but only for 2 bands. More than that and switching becomes the bigger issue than the filters themselves and the whole size & logistics of it all becomes a burden. I think you’re on the right track about cannabalizing something – no use re-inventing the wheel.

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