[TRLog] MFJ-434 & TR

[kl7ra]

Hi Jukka

Jukka writes:
>Has anyone of connected MFJ-434 voice keyer to PC driven by TR?
Support
>needed for interface between PC and DVK!


I have built interfaces for the MFJ-434. The problem is the remote
port is really
for a simple push button accessory box and ties directly into the
voice keyer
ISD1020A integrated circuit. A simple cable from this port  to a
parallel port on
some PCs will run the keyer okay, but you may find the keyer msg
buttons no
longer work which are needed for recording. Also when you do push
a button
you put 5vdc on the PC buss.

I built a simple interface box and installed a buffer between the
keyer port and
the PC. The IC 4050b buffer works fine. I add an extra level of
isolation with
the buffer driving a 5VDC reed relay. The four relays connect the
keyer's 5VDC
to each msg line. I use a battery to run the interface box and the
keyer is
completely isolated from the PC. No hum or RFI with this system
using TRLog
and six transmitters in a multi-multi.

The 434 calls for a 5 pin IDC connector which are hard to find. I
got mine out
of some old 286 PCs.

The new voice keyer by MFJ may interface directly to a PC okay.

Rich  KL7RA


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