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				Testing Channel Elements
				Posted: Fri May 28, 2021 12:36 pm
				by yardbirdjr
				Hello!
I was curious if there was a way to test and determine the frequency of channel elements.
What I have is a large assortment of misc. channel elements.
Mostly Mitrek, Micor, Mocom-70, MT-500 and MX.
Most of the labels have been worn off or were never on the elements when I received them.
Like I said I was wanting to know if there was a way to determine the frequencies, without putting them in a radio to find out. 
Please PM me with responses
Thanks in advance
David
			 
			
					
				Re: Testing Channel Elements
				Posted: Wed Jun 02, 2021 7:06 am
				by fineshot1
				Unless you have some sort of test jig from motorola that I do 
not know of the only way that I know of to test them is in the 
radio they were designed for. As far as determining the frequency
read the Khz on the crystal itself and use the models crystal calculation 
mathmatics to determine the channel frequency. You can find the calculation
in the models service manual.
			 
			
					
				Re: Testing Channel Elements
				Posted: Sun Jun 27, 2021 11:39 am
				by yardbirdjr
				Ok 
Thanks
David
			 
			
					
				Re: Testing Channel Elements
				Posted: Sat Aug 07, 2021 2:43 pm
				by YetAnotherMotoUser
				Some times you don't need the radios...
Years ago when I had a large number of Motrac / Motran / Mocom-70 / Micor elements I took advantage of the fact that they all used the same pin diameter and all were 9.6 volt powered units.
The radio manual provided the pinout, or you can look up channel elements on 
www.repeater-builder.com 
The pin diameter was roughly the same as #10 or #12 or #14 house wire (I forget which), so I cut three 3" long pieces and soldered the leads from a 9 volt battery clip to two of them.  
An oscilloscope connected to ground and the 3rd pin told me if the element was outputting anything, and a frequency counter connected in parallel with the scope gave the the frequency.
I had made some notes about the IF frequencies and the multipliers from the radio manuals, so I was able to identify the channels from the frequency counter readings.
A P-Touch labeler took care of labeling the elements.  The labeler took more time than testing the element.