[RTTY] SO2R Hardware Lockout

[Ed Muns]

The NOR-gate circuit referred to below is exactly what I built up a few
years ago for a reliable hardware interlock between two radios.  I use if
for SO2R CW and RTTY as well as MS where we have two interlocked radios
keying a single transmitter.  This allows two ops to listen to different
parts of a pileup and "race" for the next QSO, the first one locking out the
other.

My lockout box uses a quad NOR gate, 8 resistors, 2 NPN transistors and a
DPDT switch for selecting different states (FOW, Key 1 wins and
independent).  No diodes, so curious what those might be used for.

Ed W0YK

 

Joe W4TV wrote:
> The bigger problem - more critical need for interlock - is 
> those configurations using separate computers for each rig.  
> In those cases the only reliable means is to connect a 
> normally closed relay in series with PTT to each rig and use 
> the amplifier PTT line from one rig to activate (open) the 
> relay on the other rig when transmitting.  A circuit with an 
> equivalent function for two radios can be built with one IC 
> (a quad NOR package), two diodes, a few resistors and two NPN 
> transistors.