Dave,
The K3 uses open collector outputs on the band data lines. If the
amplifier does not provide pullup resistors, the band selection will not
work because the amplifier never sees a logic high level.
That the K3 uses open collector outputs has the advantage of allowing
the Band Data outputs to allow any 'logic high' voltage level that the
design of the amplifier requires, and the signalling lines can be
substantially longer when the pullup resistors are placed at the
amplifier end of the line.
But by the same token, open collector drivers do require that pullup
resistors (external to the K3) be added - some consider that a
disadvantage (I think it is good engineering design even though it is
unconventional in ham radio circles).
Apparently, your amplifier does not provide the pullup resistors. You
need to check your amplifier requirements for the band data inputs - if
it specifies TTL level signals, then you need to add a resistor from +5
volts to each of the band data outputs - if the amplifier requires some
other logic high voltage on the band data signals, then the pullup
resistors should attach to that voltage (usually at the amplifier end
rather than the K3 end).
73,
Don W3FPR
K0EKL wrote:
Has anyone constructed a cable to interface the K3 to the Tokyo Hy-Power
HL-1.5KFX amplifier?
I tried making one today, connecting K3 ACC connector pins 13, 3, 9, 14, and
12 to pins 1 thru 5, respectively, of the amplifier's Yaesu band data
connector but the amp is not tracking band changes on the K3.
Thanks
Dave Quick KØEKL
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