Turner M/JM Plus 2 Mobile
This is the Turner +2 mobile microphone. Like the +2 desk model, it featured a ceramic cartridge and a 2 transistor preamp, which is powered by a less popular and significantly more expensive 7V battery. This mic was very popular with the local group as it had a fairly crisp audio response and it was just what the doctor ordered to solve the rather anemic sounding modulation of many of the older 23 channel radios. The Turner +2 mobile mic was available in 2 forms; the M+2 (pictured) which was wired for relay switching radios, and the JM+2 (visually and functionally identical) which was wired for electronic switching radios. Either model could be converted to the other by a simple wire swap on the PTT switch. Audio gain adjustment was accomplished via a volume control knob on the rear face of the mike, which was calibrated from 0 to 9. Most radios, which were equipped with internal pre-amp stages worked well at a setting of 3 to 4. Radios without internal preamp stages often needed to be run close to maximum.
I've owned several of these mikes over the years. One of the most frequent problems with them was the sudden death of the microphone cartridge element. It would work fine, and then one day, without warning, no modulation. This may have had something to do with extreme variations in temperature. When used in a car where the internal temperature could vary from 130 degrees in the hot summer, to -10 degrees in the dead of winter, failures like these are much more likely. Another minor annoyance that I found, was the design and placement of the volume control. As designed, the control turned easily, so it didn't tak much to "bump" during use. You could inadvertently find yourself transmitting a dead carrier or suddenly being way over-modulated. You could not easily tell where it was set by feel alone, and consequently you may have to resort to turning on a dome light to reset it at night. Some people would place a strip of tape across the control to hold it securely in place. Despite these small issues, this was a very popular microphone with the local crew in the 1970's.
Sadly, the Turner company is no longer in business, and these mics are generally not available new, although new old stock pieces occasionally show up on E-Bay and other places.