CrossBand Repeater Controller Operating Manual - 9/20/18
 1.0  Introduction
A crossband repeater controller differs considerably from a standard repeater controller.   A standard repeater controller interfaces 1 receiver to 1 transmitter.  It provides PTT timeout and ID functions for 1 transmitter.  A crossband repeater controller interfaces 2 receivers to 2 transmitters.  It is essentially 2 standard repeater controllers in 1.  It provides PTT timeout and ID functions for 2 transmitters.  (Note that a crossband repeater controller can be used as a standard repeater controller with some functions left unused.) 

A crossband repeater has a receiver on one band and its associated transmitter on another band.  For example, the receiver may be in the 446 MHz band and its associated transmitter may be in the 146 MHz band. This is so the transmitter does not interfere with the receiver (no duplexer is used).  The crossband repeater also has a second receiver in one band and its associated transmitter in another band.  Continuing this same example, the second receiver would be in the 146 MHz band and its associated transmitter would be in the 446 MHz band. 

This controller adds the CW ID to the voice audio going between each receiver/transmitter pair.  Both the audio level and the CW ID level can be adjusted independently in the controller so that the voice audio can be heard while the CW ID is active.   (i.e. The voice is not blocked while the CW ID is active.)

All settings to the controller are made by setting voltages with a Volt Ohm Meter (VOM) and a small screwdriver (such as an eyeglasses screwdriver).  No computer software is used to set up the controller.  The following functions are user settable:

1)            input the CW ID (i.e. your call sign) into non-volatile memory
2)            select whether the CW ID is to be sent by one, both, or no transmitter(s)
3)            set CW ID speed between 13wpm and 20wpm
4)            set time interval for sending the CW ID (1 to 10 minutes) (typically 10 minutes)
5)            set PTT1 timeout timer for transmitter 1  (3 to 35 minutes)
6)            set PTT2 timeout timer for transmitter 2  (3 to 35 minutes)

Since computer software is not used to change the controller settings (or the CW ID), problems with installing new software when the computer operating system updates or the computer is replaced are eliminated.

2.0  Setting up the CrossBand hardware
The following example assumes that the crossband repeater will to be used to implement a 446 MHz simplex channel and a 146 MHz local repeater access using two Baofeng UV-5R handheld radios.  Of course, there are a lot of other types of crossband setups possible.  However, most implementations will be similar to this example. 

The controller board requires 7 to 18 volts at 20ma for power.  Standard shack power of 13.8VDC is fine.  A "regulated" 8 to 15VDC power adapter works also.  (A regulated supply is needed to prevent AC hum on the audio.)

First two cables with Baofeng dual plug connectors are connected to the controller according to Figure 1.  The large plug tip, ring, and sleeve connections are labelled with a LG prefix.  The small plug tip, ring, and sleeve connections are labelled with a SM prefix.  Next, insert the Baofeng Radio 1 plug into the 446 MHz radio and insert the Radio plug 2 into the 146MHz radio.  The 146MHz radio is set with the frequency and transmit offset opposite to the 2 meter repeater.  If the repeater transmits on 146.760 MHz and receives on 146.160 MHz,  Baofeng Radio 1 must transmit on 146.160 MHz and receive on 146.760 MHz, i.e. the reverse offset.   Since the 446MHz radio is in simplex mode, there is no offset set in this radio.  It transmits and receives on the same frequency.

The audio levels between the radios are adjusted by two potentiometers.  The MIC1 potentiometer adjusts the audio level going from the radio 2 speaker output to the radio 1 microphone input .  Similarly, the MIC2 potentiometer adjusts the audio level going from radio 1 speaker output to radio 2 microphone input.

To set the audio level, first adjust the (UV-5R) speaker volume control on the actively receiving radio so that the ‘audio level LED’ just barely lights on voice peaks.  This is the volume level that the receive radio should always be adjusted to.  This LED level measurement allows setting the volume out of the receiving radio to a known level, allowing the MIC potentiometer to be set just once and left fixed from then on (even if the receiving radio is turned off).   Next, adjust the associated MIC potentiometer to achieve the desired audio level into the transmitting radio.   If an oscilloscope is available, the desired audio level into the transmitting (UV-5R) radio is approximately 50mV on voice peaks. 

These adjustments are required for the audio going in the both directions.    MIC1 and MIC2  potentiometers are adjusted to achieve the correct volume level.   Turning the MIC potentiometer screw Counter Clockwise (CCW) increases the audio level.
Lastly, the ID volume level must be adjusted for both directions.  The ID volume level should be set to be loud enough to be heard, but not so loud that it interferes with the voice audio on the crossband.  There are ID1 and ID2 potentiometers to adjust the ID level in both directions.   The desired ID level will be about 5mV peak-to-peak on an oscilloscope for UV-5R radios. Turning the ID potentiometer screw Counter Clockwise increases the ID output level into the radio.

2.1  Detecting Active Receive in the Baofeng Radio
The Baofeng UV-5R active receive signal to the controller is the voltage on its speaker line during active receive.  The line has the DC voltage present on it only during active receive.  The controller detects this DC voltage using a voltage comparator and begins an active transmit when the voltage on the speaker line exceeds the set value.  The set value is controlled by a comparator potentiometer.  Comparator 1 detects the voltage coming from Radio 1.   The active receive UV-5R voltage “at the comparator” is nominally 0.68 volts.  The comparator reference voltage is set to 0.25 volts so that the comparator is not confused by voice voltage fluctuations.  Comparator 1 voltage is measured on pin 10 of the LM324.  Radio 1 voltage is measured on pin 9 of the LM324.   Comparator 2 voltage is measured on pin 12 of the LM324.  Radio 2 voltage is measured on pin 13.   The reference voltage may need to be lowered or raised for different Baofeng radios.   The selected reference voltage should be about 1/2 to 1/3 of the speaker voltage on the LM324 pin with no audio present.

2.2  Interfacing to non-Baofeng radios
The audio paths connect to the same connectors as the Baofeng radios.  The radios should not have any DC voltage on the speaker audio signal.  If they do, a capacitor must be inserted in the audio line between the radio speaker output port and the controller speaker input connector.    The capacitor value should be about 10uF, non-polarized.

Grounding COR terminal of the microphone connector signals to the controller that there is an active reception.  By grounding COR 1 on the Radio 1 side indicates that Radio 1 is in an active receive condition.  This signal is the normal COR signal provided my many receivers.  The COR signal must short to ground the COR 1 input to activate the controller.    Comparators 1 & 2 reference voltages should be set to their maximum values of approximately 4.9 volts.  This prevents possible false controller keying due to loud receiver noise.   

3.0  Setting up the Controller  
The following sections describe how to program the CW ID and how to set all timers in the controller.

3.1  Setting the CW ID’s
The following method is used to select ID1, ID2, both, or none to be active.  The potentiometer controlling the active CW ID selection is labelled “ID Select”.  The voltage is measured on microprocessor UPpin 8 test point ‘Options volts’.    The table below shows the voltage setting for each selection.  The new selection takes affect at the next power on.

ID1 adjusts the ID level that added to the audio input to radio 1.  The audio level is adjusted by MIC1.   Similarly ID2 adjusts the ID level added to the audio input to radio 2.   The audio level is adjusted by MIC2. 

3.2  How to Store Your Call Sign for the CW ID  
The CW ID is programmed one character at a time.  The character can be a dit, dah, or space.  The dit and dah have their own buttons.  The space is created by depressing both the dit and dah buttons simultaneously.   First the correct dit, dah, or space buttons are depressed.  Then the clk button is pushed and released to temporarily store that character.   A detailed example is given below.

  There is limited storage so long CW ID’s are not recommended.  If the CW ID is too long, the microprocessor locks up and will not allow any additional inputs.   If this happens, remove the power and start again with a shorter CW ID.   After the call sign is programmed, it is stored in nonvolatile memory by pressing and releasing the clk button alone with neither the dit or dah button depressed.
To initiate programming the CW ID, first hold down the dit, dah, and clk buttons together, and then apply power to the controller.  Continue holding down the 3 buttons for two seconds following power on.  Release the clk button first, and then release the dit and dah buttons.  The ID1 LED should be on.  Start the ID input by pressing down (1) dit, (2) dah, or (3) both dit & dah buttons for a space.  Then press and release the clk button to temporarily retain the first character.  The input is read by the microprocessor upon the release of the clk button.  Next press down a dit, dah, or space for the second character.  Then press and release the clk button to temporarily save the second character, etc.  All the input is saved into non-volatile memory at one time at the end of the CW ID input by pressing and releasing the clk button with neither the dit nor the dah button depressed.  If a mistake is made, start over by removing power and then depressing the dit, dah, and clk buttons together before power up as before.  Then input your CW ID. 

Example of programing the call sign K3HZP.
The call is first translated into Morse code.  The Morse code will be stored in non-volatile memory in the microprocessor.  The following sequence of dits, dahs, and spaces are for my CW ID.
K3HZP example

Each dit, dah, and space are followed by a clk press-and-release as shown in the second row above.  Lastly the ID is saved permanently by pressing the clk only with no dit or dah button depressed.  The ID1 LED goes out when the CW ID is saved.

3.3  Setting ID Timer, PTT1 & PTT2 Timeout timers
The table below shows the voltages needed to set the ID timer, the timeout timer for PTT2, and the timeout timer for PTT1.  First, the desired voltage is set on test point uPpin 11 ‘Options volts’.  Next the controller is powered off.  Then the correct combination of dit, dah, and clk buttons are depressed followed by power on.  The button combination is held depressed for 2 seconds following power on for the new value to take effect.

Here is an example for setting the PTT2 timeout timer for 8 minutes.  First the desired voltage is calculated.  The desired voltage adds time to the minimum time of the parameter.  For PTT2, the table shows the minimum time to be 3 minutes.  The voltage must be set to add 5 minutes to the minimum to total 8 minutes.  The table shows that the step size is 5/64 volts for each additional 0.5 minute.  Then 5 minutes will require 10 steps.  We always add an extra 0.5 step to make the voltage setting a little less critical.  This makes the required number of steps for 5 minutes to be 10.5 steps.  The voltage to add 5 minutes is  (5/64) x (10.5 steps) =  0.8293V.  The potentiometer labelled ‘Options POT’ is adjusted for 0.829V at the uPpin 11 test point.  The new value must be stored into nonvolatile memory to take effect.   To store it, the controller is powered down.  Then the clk and dit button combination are depressed together.  Then the controller is powered on.   Finally, the buttons are released 2 seconds after power is applied.  After the buttons are released, the new timeout value is stored in nonvolatile memory.

The last option in the above table is a little different and a little more complicated to change.  This option allows terminating the CW ID if activity on the channel stops “after” the CW ID has started.   With the default setting, if the ID starts when the PTT is depressed, it will continue until it is finished and keep the PTT depressed.  This option allows stopping the ID immediately when the PTT is normally released.  It will not ID again until the next ID timer period expires. 

To invoke this option, depress clk only before power up.  Then, power up the controller.  Now, while keeping the clk button depressed, depress the dit and dah buttons together.  Then release the clk button and then release the dit and dah buttons.  Each time that you do this, it will toggle this option on and off.  If it is off, it will toggle on.  If it is on, it will toggle off.

3.4  Setting ID speed (Words-Per-Minute)
The ID speed is set by the “ID speed” potentiometer.  The desired voltage is set on test point labelled uPpin 7  ‘IDspeed volts’.  Zero volts sets the ID speed to 20 wpm.  4.95 volts sets it to 13 wpm.  The ID is set to the desired speed by calculating this voltage using the equation:    ID wpm =  20 – (uPpin 7 voltage) * (7/5).