A modification for the Yaesu FT290R microphone
Many of us use the
FT290 as a prime mover on the microwave bands. Quite often during
initial line up testing one is asked to transmit a continuous
carrier for perhaps some minutes while the far end searches for
your signal. This usually entails holding the PTT or key down for
this period. A good strong elastic band is useful for this
purpose but can either get forgotten, or worse...snap!
The Yaesu YM-47 microphone has a slide switch on its rear which
allows one to "lock" the up/down buttons. I like many
others no doubt, never use this function and thus decided to use
the slide switch for a PTT function.
Unplug the microphone from the rig and take out the two screws
which hold the microphone casing together. Carefully separate the
two parts of the microphone casing and remove the pcb with the
microphone insert attached from the casing. Don't loose the
up/down buttons or the PTT lever in the process, but note that
the up/down switches themselves come away with the pcb. With the
microphone insert facing you, locate the pcb track shown in the
drawing. (Not all the pcb tracks are shown for clarity.)
Carefully cut the pcb track and add the 2 wire links shown, using
insulated wire. Re-assemble the microphone and there you have it.
The up/down function is retained but the slide switch will now
work in parallel with the PTT switch.
Slide the switch to the "on" position and you can send
continuous carrier for as long as the other station needs it
while you can get on with your ham sandwich!
The usual disclaimers regarding modification of equipment apply.