2
Mic Connector:
The next step is to determine
for certain
the function of each pin on the mic connector. If your radio has a round
8-pin connector the process is very straight forward, but if your radio uses a RJ-45 (telephone like) connector, the process can be a
little tricky! To wire either connector you
must
have the Users Manual for your radio available for reference.
To minimize the possibility of making a wiring mistake, we have provided a wiring table for you to complete in the Jumper Wire
Diagram. As the correct signal is determined for each microphone pin, you should record it in the table. You might want to use a
pencil for this process, in case you need to make a change or use the table for a different radio later.
If your radio uses the 8-pin round connector, you should be able to copy the signal names and their associated pin numbers directly
from the radio manual into the appropriate lines of the Jumper Wire Diagram. When copying this information, be sure that you
refer to the actual pin numbers given. Do not attempt to determine the pin number from any illustration of the connector. When
you are finished, it would be a good idea to double check the accuracy of your information by testing continuity between chassis
ground and the pin that is supposed to be Ground on the connector.
If your radio uses an RJ-45 mic connector, you cannot assume that the pin numbers in the manual are listed correctly. If the
manufacturer has not followed the industry standard numbering conventions, the lines will be in the correct sequence, but in reverse
order (Pin #1 = Pin #8)! Unfortunately this is not at all uncommon. On a number of occasions we have even found disagreement
in the numbering system between radio models from the
same
manufacturer! You should
never
assume the position of Pin #1 on
any RJ type connector, based on the diagram in the manual. Since these lines often times have Accessory Voltage on them, wiring
the connector incorrectly can have catastrophic results!
The best way to insure you have the correct wiring order is to verify with a multimeter where the Ground and PTT pins actually are
on the connector. Because the RJ-45 pins are dangerously close together and very fragile, we will use the Interface Cable and Mic
Adapter board to help make these tests. Since the adapters RJ-45 and 8-pin round connectors are wired in parallel (Pin #1 = Pin
#1), you can use the pins on the back of the boards round connector for testing. These pins are much easier to probe than an RJ-45
pin and are very clearly numbered on the pc board. Turn the radio OFF and attach the Mic Adapter board to your radio using the
Interface Cable.
Start the identification process by checking for continuity between the radios chassis and the connector pin number that is listed as
Chassis Ground in your radio manual. For example: If the manual says that Pin #3 is Ground, then check continuity between the
radio chassis and the third pin (Pin #3) on the round connector. When making this measurement, remember that you are looking
for “Zero Ohms”. There will no doubt be some amount of continuity between several other pins, but remember that the one you are
testing for is a “short” to ground! If you don’t find continuity on the pin that you tested, then the pin numbers must be reversed in
the radio manual. You can verify this by testing the third pin from the other end (in our example Pin #6). You should find
continuity on that pin if the order is in fact reversed.
If you would like to up your confidence even further, you can turn your radio ON and test the PTT line. Your radio should be
attached to an antenna or dummy load for this test, since you will be transmitting briefly. In this test you will be manually keying
the transmitter by briefly shorting the PTT line to Ground. If one is available, use a small value resistor (a few hundred ohms) to
short the PTT line to Chassis Ground (chassis - not the ground pin). The resistor is not really necessary, but a good idea just in
case you are shorting the wrong pin! If the radio transmits, you can be absolutely certain that you have the pin numbering correct.
G r a y
O r a n g e
B la c k
R ed
G r e en
Y e llo w
B lu e
B r o w n
8 - P in P lu g
( R e a r V ie w )
R J -4 5 P lu g
( R e a r V ie w )
1
8
M ic A d a p te r R a d io In te r f a c e C a b le - W ire d s tr a ig h t- th r o u g h ( p in 1 to p in 1 , e tc .)
3
5
2
8
6
4
1
7
