EMRFD Message Archive 8896
Message Date From Subject 8896 2013-08-05 11:52:10 ve7cqy Motorola Microphone cartridge I picked up a "classic" Motorola mobile microphone at a hamfest. It has a dynamic cartridge with preamp in it. I cannot obtain any schematics of the audio module that it interfaces to. Before I attempt to try my own circuit, has anybody interfaced to this type of mike or know where I can find the audio module cct? 8898 2013-08-05 19:56:20 Kerry Re: Motorola Microphone cartridge K9STH, Glen Zook, knows a great deal about Motorola products as he ran a major Motorola service centre for many years.
His website is http://k9sth.com/ and his e-mail address is there.
Glen is a very nice bloke and I'm sure he would help you.
8899 2013-08-05 19:56:32 Kerry Re: Motorola Microphone cartridge Funny; I replied to this message but the reply seems to have been lost in the aether. :)
I suggested contacting Glen Zook K9STH; Glen ran a major Motorola service centre for many years and knows a great deal about Motorola products.
His website is http://k9sth.com/
He's a very nice bloke and I'm sure he will help.
Now, let's see if this message makes it!
8902 2013-08-06 19:36:29 ve7cqy Re: Motorola Microphone cartridge Thanks for the contact. I will email him.
In the meantime I tried using a various voltages up to 9 volts fed through a 10k resistor into the + side of the cartridge. Mike works fine. Its just a matter of optimizing what impedance the preamp wants to see now.
8912 2013-08-07 21:09:30 ve7cqy Re: Motorola Microphone cartridge I rigged up an oscillator/speaker into the mike while adjusting the frequency, voltage and impedance. Mike works best at 8 volts (you can run it at 12 but performance levels off at 8) and 3.5k resistance. The cartridge seems optimized for the midrange spectrum as you would expect.
Glen is looking up how Motorola does it.