eHam Forums => Misc => Topic started by: ZL2DAT on May 29, 2008, 05:01:39 PM

Title: Custom mic cut-off switch
Post by: ZL2DAT on May 29, 2008, 05:01:39 PM
Hi all,
I am in a wheelchair and as a consequence I cannot manage to unplug my microphone myself.  I was wondering whether someone could design a cut-off switch, so that when the cut-off is activated the rig will not transmit even if the push-to-talk button on the mic is bumped?
I  am envisaging a switch that would plug into the microphone jack of my Yaesu FT897D at one end and the other end would plug into the microphone itself. (preferably a rocker switch as opposed to a push button switch)

The reason I want a cut-off switch so much is that it will enable me to listen to ham bands that my aerial is not tuned for transmission on, without fear of accidentally bumping the mic and causing a transmission that could damage the rig. I would also use a cut-off switch when I want to listen to non-ham frequencies, of course I would NEVER want to transmit on those. Do any of you think you could design and build such a switch for me?

Could you also give me some idea of the cost that would be involved please?

Yours faithfully,
Steven Mulvay ZL2DAT

Title: Custom mic cut-off switch
Post by: NA0AA on May 29, 2008, 09:04:13 PM
I cannot do the work for you from my QTH, but I will say that a standard 8 conductor modular plug is used on the US version of that radio - at the computer shop you can buy a cheap 'extension' cord.  Install a switch in the middle of this cheap cable that will disable the PTT - an spst switch in the PTT line so that if you open the switch you the mic ptt is disconnected will do the job with only one simple wiring change, and no mods to the radio.  

If you ever want to sell this rig, you then disconnect the extension cable and your rig is still stock.

Regarding out of bad operation:  Most amateur radios will not transmit out of band but I can understand your caution.

Title: Custom mic cut-off switch
Post by: WB6BYU on June 03, 2008, 03:38:14 PM
At least one of my radios comes with a transmit disable
switch on the back of the mic.  It is a small slide switch
on the back of the microphone case where it is unlikely to
be operated by mistake.  I suspect one could add such a
switch to most hand microphones