While it’s mainly a local VHF/UHF communications issue, stuck microphones can be a real problem.
A stuck mic situation is when a radio operator inadvertently transmits for an extended time because they have unintentionally triggered the push to talk or transmit switch on their radio. Consequences of a stuck mic range from being a nuisance to a life-threatening disruption. At best a stuck mic ties up a repeater or simplex frequency with dead air or noise. At worst it blocks urgent communication during a disaster net or public service event.
One common stuck mic situation involves a mobile unit with the hand-held mic loose in the vehicle where it might get wedged into the seat to trigger the PTT button. Best practice here is to keep the mic clipped into a hanger when not being used to minimize inadvertent transmission.
Another common situation involves mic accessories with HTs during a public service event or emergency deployment. When using a speaker-mic or headset, ensure that the PTT button is protected from accidental triggering. Also, the Yaesu FT-60 is a wonderful handheld radio and many hams have them, but they (and others like them) have a squirrely speaker/mic jack that is prone to false triggers when the connector is not seated completely. So make sure your accessory is connected securely and not prone to pulling out when the radio is clipped to your belt or in a pocket or something like that.
In any case, awareness is our first line of defense. Be aware that a stuck mic is a problem and that you might be the culprit.
Keep an eye on your transmit light to make sure it’s not on when you’re not talking. Push your speaker-mic plug in periodically. Protect your PTT switch. If you’re working a net or event and it’s unusually quiet, a stuck mic might be the reason. Again, be aware.
Most repeaters have a timeout feature where it will cut off a stuck mic transmission but that setting may be three minutes or more and seems like a painfully long time during a net. If you’re working an event on simplex, the limitation is the transmitter timeout of individual radios. We should all set our own radios to time out at no more than two minutes, particularly if you have an FT-60 with a speaker-mic accessory. Note that the default Yaesu transmit timeout setting is off so unless you’ve set it, it will never shut off. This is our second line of defense in a net or event, the first being awareness.
The third line of defense is much more difficult—tracking down a stuck microphone. There are two stuck mic scenarios: intermittent and continuous.
With an intermittently keyed mic you have a brief chance to alert people of the stuck mic, and the offending party may hear the call and check their equipment to fix the problem. Unfortunately intermittents may not last long enough for the individual radio or repeater to automatically time out, so these can be nasty to deal with.
A continuously keyed mic gives you no opportunity to alert the transmitting operator since they can’t receive while transmitting (exception is if the offender has a dual-channel radio where you can alert them on the other frequency). Here you need to listen carefully for their voice or background noise that might give a clue as to their identity or location. Recognizing voices or unique background sounds may offer a clue as to the people or place involved. If you can figure out who they are or where they are, you can contact them or even send somebody there to alert them that they have a stuck mic.
In the case of either intermittently or continuously stuck mics, a more powerful transmitter can be used to talk over them to alert people of the situation. The offending operator may hear it on a different radio nearby or at least other event participants can look around and ask around.
As a last resort you may have to do some radio direction finding to locate the transmitter with a stuck mic. Here is where foxhunting is a practical skill. If the stuck mic cannot quickly be located the net should switch to the secondary frequency.
In summary, stuck mics can be a real problem. Awareness is most important so add this to our EmComm discipline of situational awareness. You should set your own radio transmit timeout timers. Finally, know what you can do to track down a stuck mic if needed.
I’m sure readers here have more info and ideas on the topic so we welcome their comments.