[CQ-Contest] Re MFJ-432 Mods

[K4tmc at aol.com]

First, thanks to WM3T, K8CC, K8DO, AE0Q, VE3FU, K1KY, K4SB, WM5R, KL7RA, 
N6KI, KK1L, WD4K, & K8ZT for their thoughts, suggestions, and experiences in 
using and modifying the MFJ-432 voice keyer.

Second, here is what I have done.  I have taken K4SB's idea (Thank's Ed) of 
using a computer mouse and have modified a spare 2-button mouse to give me 
remote function of Messages 1 and 4, and the Repeat Message 1 switch.  Once I 
took apart the mouse, I found that it is just not a simple switch box!  Even 
though there are 2 small micro-switches, there is a circuit board with an IC, 
surface-mounted-devices, and the roller-ball mechanism/electronics.  The 
wires coming out of the mouse do not give you direct connection to the 
micro-switch contacts; therefore, I had to get out the X-acto knife and 
soldering iron and do some re-engineering of the traces around the switches 
and cable connector.  Since there was no third switch available, I removed 
the ball and installed a small micro-switch through the top of the mouse and 
will use it as the Repeat Message 1 switch.  I found a spare mouse extension 
cable in my junk box, and clipped it at about 8 inches from the connector.  I 
drilled a hole in the 432 back, inserted the cable with just the mini-DIN 
connector hanging outside, and used a cable tie as a strain relief.  The 
connections to the 432 were made to the terminal connector strip on the back 
of the unit by passing the wires back through the open slot in the 432 
cabinet.  I just used a single wrap of the wire and a drop of solder.  Since 
several of the terminal pins were not in use, I routed a wire from the Repeat 
Message 1 switch to one of the spare terminal pins.  Everything works just as 
I envisioned.  Sine a mouse is designed to be moved about, and trying to flip 
a microswitch exerts some lateral force; I found that I needed someway to 
keep it from moving around so easily.  The fishing tackle box came to the 
rescue.  I simply glued inside the mouse a 2 oz fishing weight.  I will have 
to wait until the next major phone contest to determine if there is need for 
more improvements.  This all looks neat now that everything is back together. 
 And the mouse cord can be disconnected right at the back of the 432.

73 & High Rates,
Henry Pollock - K4TMC


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