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Modifying the TLN4635B MICOR Station Control Module By Kevin Custer W3KKC

Concept:
Modify a Station Control Module for better duplex use in a repeater station.

Description:
A technician may want to instantly disable the transmitter to check for desense.  This modification rewires the "Line Disable" switch to allow disabling of the PTT and enhance the use of an outboard repeater controller.  The modification will also eliminate an outside source from inhibiting the PTT.  A pilot lamp (LED) can also be added to indicate when the transmitter is active.  Also, you may desire to have the transmitter channel element keyed with the exciter.  This prevents local oscillator leakage that often can be heard for a good distance from the repeater site.

Keying Switch and LED Modification:
1. Completely remove Q10 and Q15 from the board.  This disables the ability for an outside source from inhibiting the PTT.
2. Clean out the hole that the collector of Q10 was in.
3. The common (center pin) of both sides of the Line Disable switch should go to ground from the factory.
4. Unsolder the pink wire that is connected to the top side of the switch's normally open contact from the circuit board.
5. Solder the removed end of the pink wire in the opened hole where the collector of Q10 was.
6. Connect a wire from the other normally open contact on the other side of the Line Disable switch to the base of Q17.
7. Drill the front panel and wire a red LED through a 2.2 k resistor from the collector of Q18 to ground.

PTT from the outboard controller is connected to pin 5 (Local PTT) on the card.  This is done on the backplane to allow the card to be pulled if needed.

The above modifications will disable the ability for the Station Control Module to create a PTT by using one side of the "Line Disable" {Now "PTT Disable"} switch to short out R62 and thus preventing Q17 & Q18 from creating Keyed A+.  The other side of the switch grounds the cathode (banded end) of CR8 thus preventing Q11 from creating Keyed A-.  The added LED will indicate when the exciter is keyed (On Air Lamp).

Keyed Exciter Channel Element Modification:
Q8 can be used to control the keying of the exciter channel element for the benefits stated previously.
Simply remove or cut out CR4, CR5, and CR6, and insure JU4 is in place.
Use pin 2 (Ant Sw / Audio Mute) on the backplane to supply a ground to enable the Channel Element by running a wire from there to the transmitter interconnect pin 19 (F1 Channel Element Select/Enable).

The module can be run in the PL Disable mode full time if necessary.  Just pull the incandescent lamp out of the socket.
Relabel the Line switch to indicate "PTT Disable."
The PTT switch (top switch) will work as originally designed.

Note from the editor, Mike WA6ILQ

The MICOR station has no "Power On" indicator.  While you are digging into the Station Control card, it might be a good idea to mount a green LED into the front panel and add an appropriate series resistor from the +12vDC line to ground.

This modification was prepared by Kevin K. Custer W3KKC, Dec 5 1999
Comments welcome, just email kuggie /at/ kuggie /dot/ com

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This page is © Copyright Dec 5, 1999 and the date of last update by Kevin K. Custer W3KKC.

Motorola® and MICOR® are registered trademarks of Motorola Inc.

This web page, this web site, the information presented in and on its pages and in these modifications and conversions is © Copyrighted 1995 and (date of last update) by Kevin Custer W3KKC and multiple originating authors. All Rights Reserved, including that of paper and web publication elsewhere.