View Full Version : Kenwood TR-7500 microphone Help Needed
01-17-2010, 02:55 AM
Hi to all. I'm studying for my tech license. I purchased a Kenwood Tr 7500 2 meter mobile. The wires have come loose from the mic pin that goes into the radio and I need help rewiring it. I have a manual that came with it, but I cant figure it out using it. Its a 4 pin mic. There are red, white, bare and black wires, not sure where to solder.
Any help will be appreciated.
There are RED, WHITE, BARE/SHIELD and BLACK wires, not sure where to solder.
You really need a VOM or DVM (continuity test) to assure correct wiring here.
A VOM/DVM is a VERY BASIC test instrument -- and a cheap one sells for less than $5 at Harbour Freight.
THERE ARE NO STANDARDS for the Far East Big 3 radio mfg. in using cable wire colors for microphone functions !!!
Try this with a VOM and see if you register continuity when you close your microphone connector.
1. RED and BLACK are normally PTT(+) and PTT(-)
2. WHITE maybe AUDIO(+), and the SHIELD/BARE is AUDIO(-) and MAY surround/shield the AUDIO (+) line.
MODS.DK should have the TR-7500 manual
BTW, IF you have local FM repeaters that require CTCSS (very like), then make sure that you have the optional CTCSS (PL) board installed.
As far as tone (CTCSS) boards -- look at PIEXX offerings for plug-in replacements for Kenwood, Yaesu and Icom FM radios.
OR Com-Spec offers their popular SS-64 board
Nice pictorals of radio showing the number of screws and connectors that are
required (many) for removal of PC board and installation of the CTCSS board.
Permits usage of the SUB switch for CTCSS encoder usage - nice
01-17-2010, 10:09 PM
I didnt know that about the colored wire, I guess that would be to easy. I have the original manual for the radio. I will try your suggestion. Thanks for the info I couldnt find anything on a google search. I'm looking forward to getting my licence so I can use the radio. I want to at least be able to listen in the mean time. I built a J pole antenna and hooked the radio up but didnt here anything. Maybe the mic has to be working properly for it to receive. Not sure.
I didn't know that about the colored wire, I guess that would be too easy.
IF you had a Shure, Turner, Astatic, EV or other American made microphone -- those manufacturers tried to stay somewhat consistent in wire color usage -- at least with the same mfg. This was partly due to American manufacturers selling their microphones with tinned leads (no connector) as an option for hard wired applications.
The wire color problem "appeared" when the Far East manufacturers started to "outsource" their microphones to third parties.
Some of these third parties used "what ever cheap wire they could get" -- that sometimes meant not using the colors of the original mfg. Their argument was -- it does not matter -- we properly wire the microphone head and circular plug (consumer doesn't wire these microphones themselves).
One Far East microphone cord I repaired once .. had baby blue, pink, yellow, white and black for wire colors -- that was a weird one!! I had to tone out all the wires to properly install the connector!!
I built a J pole antenna and hooked the radio up but didn't here anything. Maybe the mic has to be working properly for it to receive. Not sure.
Go to a local radio club meeting or seek out the technical committee that administers the VE exams in your area. You could take your radio to their shack and have them hook it up to the antenna/power to see if the radio if OK.
01-18-2010, 12:20 AM
And you won't need the mic to listen.