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British Columbia Frequency Modulation Communications Association


VE7RPT-VHF Modifications


This repeater came from commercial service. It so happens that this particular model contains the sought after 142-150.8MHz RF components, making it an ideal candidate for conversion to the ham band.

This page will detail the modifications made to this repeater to interface with the RLC-3.


Chassis

Originally, the backplane in this chassis was a TLN5979A. This repeater is newer than some of the ones we have, and was a DVP model in its former life.

We have a number of Micor's in service, and in order to keep maintenance simple, we chose to change out the backplane with a board that is common in our other repeaters, the TLN5644A.

The repeater is setup for REPEATER (RT) NON-WIRELINE, as such, the factory jumpers are configured as:

    	JU1 IN
    	JU2 OUT
    	JU3 OUT
    	JU4 IN
    	JU5 IN
    	JU6 OUT
    	JU7 OUT
    	JU8 OUT
    	

There are no other jumpers or wires installed (yet).

All factory modules are removed. The only one that will be used in the final configuration is the Station Control Module.

We have a 12VDC plant that these repeaters are connected to on site, as such there is a requirement to operate of 12V exclusively. This means that a source of 9.6VDC is required for station operation.

An LM-317T regulator is fitted into the chassis, set for an output of 9.6VDC. This is accomplished with a 255ohm resistor from Adjust to Vout, and a 1.6kohm resistor from Adjust to Ground. The regulator is installed behind the Audio and Squelch Board, with an insulating washer and heatsink compound:

VReg

There is also a 0.1uF bypass cap between Vin and GND, and a 100uF cap between Vout and GND.

The regulator is wired into the factory power connector on the backplane.

On the power connector, J1, Pin 1 is jumpered to Pin 6, and connected to the input of the LM-317T. Pin 4 is jumpered to Pin 5, and connected to ground of the LM-317T. Pin 3 is connected to the output of the LM-317T (9.6V).

Pwr Conn

Screw terminals TB3,10 and TB2,1 are connected together, and this becomes the +12VDC input to the station.

Screw terminals TB3,1 and TB2,2 are connected together, and this becomes the Ground input to the station.

New Pwr

This modification is compatible with 12W UHF stations as well.

Power to the main chassis is now provided through the Powerpole connectors.

There are a couple of more modifications done to the backplane. In order to ensure that the RX oscillator is running all the time, a jumper is installed from Pos7,23 to J2,30. This grounds pin J2,30, which is the channel element enable pin.

RX Osc

With the lack of factory modules in the station, the TX oscillator needs to be keyed as well. We do not want the TX oscillator running all the time, in order to reduce interference with local handhelds and other radios on site. As such, part of the modification to the Station Control Module will isolate the Antenna Switch circuitry, and allow it to be used to key the TX oscillator during transmit. To utilize this function, a jumper is run from Pos2,2 to Pos3,14. This is the same as putting a jumper from J5,14 to J5,19.

TX Osc

Also due to the lack of factory modules, there is no path for the receiver audio to get to the audio amplifier. Add a jumper on J2 from Pin 6 to Pin 14. This will take the R1 audio and route it to the audio amp on the Audio and Squelch board.

RX Jump

That completes the modifications to the backplane, for now. At the end we'll go over the connection points to interface to the RLC-3.


PL Decoder TRN8834A

Nothing much to do here, just check for JU801 is IN, and a Vibrasponder reed is installed (136.5Hz in this station).


Receiver Interconnect Board TLN5456A

Because this is a repeater station, we want to be able to do full duplex.

CR957 must be removed in order to allow for the station to be used in full duplex mode.

CR957

The remainder of the jumpers on the board are configured as:

    	JU951 IN
    	JU952 IN
    	JU953 OUT
    	JU954 OUT
    	JU955 IN
    	JU956 IN
    	JU957 IN
    	JU958 IN
    	JU959 IN
    	JU960 IN
    	CR957 OUT
    	

Audio and Squelch Board TRN6006A

The jumpers on this board are configured as:

    	JU201 OUT
    	JU202 OUT
    	JU203 OUT
    	JU204 OUT
    	

JU201, JU202, and JU203 are out because this is a PL equipped station. JU204 is out to enable "AND" squelch. This isolates PL and COS to the RLC-3 so the RLC-3 can make the proper squelch decision based on programming.

Additional modifcations are made to the Audio and Squelch Board to enhance its operation. These modifications are based on information obtained from Repeater Builder.

The trace to P903,8 is cut just behind the via, and a jumper is installed from IC202,10 to P903,8 using the pads available on the component side of the board:

A-S Front

A 100k resistor is added between IC202 Pins 6 and 5 (ties pin 6 to ground through resistor); and jumper IC202,6 to intersection of C211 and C213 (pad available on solder side of board):

A-S Back

The trace leading from the anode of CR201 is cut, this disconnects IC202,13 and still leaves the bypass capacitor in place:

A-S Front2

Finally, cut the trace between IC202,14 and P903,13 to defeat "PL Disable" and allow all signals to be heard on the local speaker without having to put the Station Control Module in "PL Disable Mode".

The only thing left to do is label the board as modified, and install it back in the station.


Receiver TLD5782AV

As this is the perfect bandsplit board for the ham band... no changes required!


Exciter TLD5802A

This board is configured for interfacing to a factory PL encoder.

The jumpers are set as:

    	JU401 OUT
    	JU402 OUT
    	JU403 IN
    	

Ensure R401 removed for hi-Z input (vs. 600ohm), to ensure we can drive the exciter with the audio from the RLC-3. It also removes the DC bias from the MIC-HI line.

This exciter came from DVP duty, and as such, has a jumper installed that allows for direct modulation injection after the limiter. This is normally used for Coded Audio input, but will be used for DPL injection in our application.


PL Encoder Board TLN5731A

No changes. Vibrasender reed (136.5Hz) is installed.

The factory jumper from Pin 701 to P964 on TX Interconnect Board is installed to allow for the "PL Inhibit" function to be utilized. When this pin is grounded, the station will stop transmitting the PL tone.


Transmitter Interconnect Board TLN5894A

As stated above, the jumper from P964 to Pin 701 on PL Encoder to wire out "PL Inhibit" is installed.

This board is the Repeater Station version, as such, it has some components omitted. This is good. If it happened to be a Base Station version, like a TLN5647A (BASE), there are some additional modifications required.

In this case clip R911 to disable the current limiter stage. This prevents A+ from being present on the Antenna Switch pin when the station is in receive mode. The Antenna Switch control will be used for keying the F1 oscillator in the absence of a Squelch Gate card. (The associated current limiter components are not present in repeater stations.)

R911 Cut

Station Control Card TLN4635B

The modifications to this card will convert the "Line Disable" switch into a "PTT Disable" switch, to allow for checking de-sense, or shutting off the transmitter when desired.

It will also add a "PTT Indicate" LED, to show the status of the repeater PTT line.

It modifies the antenna switch circuit, to make it an open-collector, active low signal, to be used to key the TX oscillator.

The initial jumper configuration for this card is set to:

    	JU1 IN
    	JU2 IN
    	JU3 IN
    	JU4 IN
    	JU5 IN
    	JU6 IN
    	JU7 IN
    	JU8 IN
    	JU9 IN
    	JU10 OUT
    	JU11 OUT
    	JU12 OUT
    	

Because this is a PL equipped station, JU9 is IN.

These modifications are based in information found at Repeater Builder.

JU3 is cut to prevent any external inhibit signals from preventing the station from keying.

A wire is added from the open N.O. terminal of the Line Disable switch to the cathode of CR9. This will allow us to manually inhibit the PTT using the existing "Key Inhibit" circuitry of the Station Control Module, by using the "Line Disable" switch.

The front of the card is drilled, and an LED mounted for the "PTT Indicate".

Ground the cathode of the LED to the common terminal of the switches. Connect the anode of the LED through a 2k2 resistor to the collector of Q18 (which is also the cathode of CR24). This will indicate when the station is keyed.

Re-label the "Line Disable" switch to "PTT Disable", and label the LED.

StaCont Mods

To convert the antenna switch to provision for keyed TX oscillator, cut CR5 to remove A+ bias, and ensure JU4 is IN. As mentioned in the backplane modifications jumper from POS2,2 to POS3,14.


RLC-3 Interfacing

The station should now be modified, and operate normally.

The audio to the controller can be had at J2,6. The level is controlled by the "Line Level" pot on the Audio and Squelch board. This connection point will vary a little bit as you adjust the local volume, but it does settle back and remain pretty constant.

Add a jumper from J2,6 to TB3,9 to provide a convenient connection.

Audio from the controller should be routed to TB3,20. This is the Un-notched Mic-HI line.

PTT is available on TB3,8. It is active low, ground to transmit.

COS is available on J2,13. Jumper this to TB3,11 for a convenient connection. This signal is active low, it will be 0V with a received carrier.

PL Indicate is available on J2,10. Jumper this to TB3,13 for a convenient connection. This signal is active high, it will be at 9.3V when a valid PL tone is being received.

In summary, the connections to the RLC-3 look like:

RLC-3 DB9 Pin Function Micor Connection Wire Color Notes
1 Ground TB3,1 Shield Not connected at radio
2 PL Indicate TB3,13 Brown Active High
3 PTT TB3,8 Red Active Low
4 Audio to RPTR TX TB3,20 Blue  
5 Audio from RPTR RX TB3,9 White  
6 Ground   Shield Jumper to 8, not connected at radio
7 COR TB3,11 Green Active Low
8 Ground   Black Jumper to 9 and 6
9 Ground TB3,1 Black Jumper to 8

A pigtail with a DB9(f) is wired to the above points. A DB9(m)-DB9(m) cable is constructed to connect to the controller.


Line-up Instructions

Perform all of the required alignment procedures per the manual. Identify the Modulator Sensitivity (Mod Sense) value for the exciter.

This is accomplished by sending a 1kHz@1000mV tone into the Mic HI line, TB3,20. This will put the limiter in the exciter into full clipping. Adjust the IDC pot for 5kHz deviation. Reduce the level of the tone until 3kHz deviation is obtained. The tone level at this point is the Modulator Sensitivity value, record it on the front of the station. See the explanation of pre-emphasis and de-emphasis here for further information.

Feed an on-channel, 1kHz tone @ 5kHz dev signal to the receiver and measure the level at TB3,9. Use the "Line Level" pot on the Audio and Squelch Board (under the shield) and set the output to 500mVp-p. Recommended level for the RLC-3 is 100-500mVp-p.

Set the DIP switches on the RLC-3 radio card for OFF, ON, OFF.

Setup the controller to make the port a repeater.

Connect the radio to the to the controller's corresponding radio card.

Again, feeding an on-channel, 1kHz tone @ 5kHz deviation signal to the receiver, adjust the RX pot on the radio card for 1Vp-p at J4.

Again, feed an on-channel, 1kHz tone @ 5kHz deviation signal to the receiver and adjust the TX pot on the radio card for twice the Mod Sense value, measured at TB3,20. This puts the exciter into soft clip. Note: It may not be possible to get the full 6dB output from the controller, in that case, leave the TX pot set to its maximum value.

Verify the TX deviation does not exceed 5kHz.

Set up the tone (CW, etc.) level by entering the following command:

	050 09 0x
	040 6000 0001 1000
	050 09 00
	

The first command sets the output port (x is the transmitter you are working on). The second command sends a 1kHz tone for 60 seconds. The third command resets the output to null.

While the tone is being sent, set the TN pot on the radio card for about 2.0kHz deviation.

If this is the first port being set up, the voice level will need to be set too. Enter the following commands and set the "Voice Level Adjust" pot on the main board for about 2.5kHz deviation:

	050 09 0x
	036 001 002 003 004 005 006 007 008 009 001 002 003 004 005 006 007
	050 09 00