[CQ-Contest] Mods to MFJ-432 Voice Keyer?

[k8cc]

At 08:33 PM 11/2/00 -0500, K4tmc at aol.com wrote:
>And, has anyone found a connector that fits the remote terminal pins on the
>back?  That way I could just leave the standard switches alone and use remote
>switches for the basic functions I need.  It would be much more convenient to
>have the few needed switches right at the keyboard.

Henry,

The connectors are standard .100" headers.  The ones I used were Molex "KK" 
series.  At first glance, the connector does not appear to be too rugged 
and there is no positive latch.  However, as long as you keep the strain 
off the cable it works fine.

The buttons on the MFJ-432 don't switch to ground, but rather to 
+5V.  Fortunately, MFJ provided +5V on the connector, so there is no need 
to cobble up another voltage source.

The slickest thing to do is to use the computer to control the 
MFJ-432.  NA, CT and TR all define pins on the LPT port which are toggled 
when the F1-F4 keys are pressed on SSB.  These signals can drive 
transistors or optoisolators to fire off the MFJ-432.  Due to the positive 
switching configuration mentioned in the previous paragraph, I opted to use 
NEC PS-2501 optoisolators (cheap, about a buck apiece from DigiKey) which I 
mounted in the DB-25 shell.  When I get time I'll draw up a schematic and 
post it on my web site, however don't count on it immediately with SS CW 
two days away.

I set up my MFJ-432 this way for the WP3X trips I took in 1997 and 1998 and 
it worked flawlessly.  It certainly is no DVP, but it works the same for 
CQing and its the simplest solution available for use with a laptop 
computer.  Certain program features like CQ repeat are far more convenient 
to use than the hardware solution in the MFJ-432.

73,


Dave/K8CC


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