ZETRON 37-MAX, Installation Manual

Page: 41 / 90

Section 5. Installation
5-6
again (cycle the Disable button as necessary to get the encode frequency back to 136.5
Hz).
7. DCS Encode Polarity
:
After completing step six satisfactorily, press the Disable button
once to start the DCS encode of "023". Verify that the code "023" is being transmitted. If
code "047" is being sent instead, then the DCS Encode polarity must be changed using
either command "216#" or "215#". Verify that the encode is being sent at approximately
15% of full channel deviation.
8. Carrier Detect
:
Press the Disable button once to enable the Repeat Audio mode. Supply
and remove a full quieting signal in the receiver frequency and adjust R35 (
EXT COR
) as
necessary to get the Carrier LED to track the presence of receive signal. If the LED
appears to be operating 'backwards', locate JP5 (
COR POLL
) and rotate the two jumpers
there a quarter turn. Then, readjust R35 as necessary.
NOTE:
Some duplex radios disable their carrier indication output while transmitting. If this is the
case with radio being used, the receiver must be modified to supply carrier detection
regardless of the transmitter's condition.
9. Repeat Audio Level
:
Supply a full quieting signal with a test tone of known deviation on
the receive frequency of the repeater. Adjust R2 (
RX LVL
, not R3
TX LVL
) for unity gain
through the repeater. This means that the deviation measured on the transmit frequency
during this test should be the same as the known deviation of the signal being supplied on
the receive frequency. If unity gain cannot be reached using R2 (or is reached only with
the potentiometer 'pegged'), try moving jumper JP3 to the opposite position, and then run
the test again.
Once the level has been set, supply a signal on the receive channel with test tones of 500
Hz, 1000 Hz, and 1500 Hz while monitoring the transmit frequency. The deviation should
remain reasonably flat for all three tones. If not, move jumper JP6 to the other position
and readjust the receive level (R2) if necessary.
NOTE:
If using a DTMF digit as the test tone, do not hold the digit continuously for more than eight
seconds, or a RESET will occur. If the signal is not being repeated, check that the receiver is
supplying audio to the Model 37-MAX. Some duplex capable radios disable their receivers
while transmitting. If this is the case, the radio will need to be modified before continuing.
10. This completes the Alternate Test Procedure. Cycle power on the Model 37-MAX to
return it to normal operation.