Turner M/JM Plus 3 Mobile
This is the Turner +3 mobile microphone. Like the +3 desk model, it featured a ceramic cartridge and a transistor preamp with an audio compression stage which automatically adjusts the gain for consistent output, even when you spoke closer or further away from the mike. Like the +2 mobile mic, the +3M was powered by a less popular and significantly more expensive ($5 vs. less than $1) 7V battery. This mic was also very popular with the local group. The +3M was ergonomically better designed than the +2M as it had a smoother case, with rounded corners, and a slide control for the gain adjust, which was much more difficult to accidentally move, and could be set by feel, if necessary. The tone quality of this mic, like with the desk mic, was a bit "bassier" than the +2, which had a more crisp audio response. Some radios sounded much better with this mic, especially SSB models. The Turner +3 mobile mic, like its +2 cousin, was also available in 2 forms; the M+3 wired for relay switching, and the JM+3 for electronic switching radios. Also, like the +2, either model +3M could be converted to the other by a simple wire swap located just under the battery compartment. As mentioned before, the audio gain was accomplished via a slide volume control on the rear face of the mic, which did not have any numbers, only indicating "LO" and "HI" at the opposite ends. Like on the +2, most radios with internal pre-amp stages worked well at a setting of 1/3 to 1/2. Radios without internal preamp stages often needed to be run close to maximum.
I've owned two of these mics over the years. After 30 years of use, the coiled cords have discolored and have begun to disintegrate and turn "gummy", but otherwise they still work.
Sadly, the Turner company is no longer in business and as a result, these mics, and replacement parts for them, are no longer available new.