Item Description: For sale today is one GPS/PLL board and an LPRO-101 interface board. This board set allows the LPRO-101 to sync to the GPS. The GPS/PLL board has Square Wave, Sine Wave, and 1PPS outputs all derived from the LPRO-101 10MHz square wave input to the GPS/PLL board. The LPRO-101 in the pictures is not included.

See the individual board listings for more information. There is no manual for this, all of the information needed is in the listings.

You will need two SMA cables (not supplied) to connect between the GPS/PLL board and the LPRO board. 

Power required for the GPS/PLL board is 24VDC at under 100mA. The board has a on board regulator to convert the 24V to about 10V and then linear regulators for the other voltages. Power required for the LPRO-101 board and the LPRO-101 unit is also 24V. The mating power connector for the LPRO board is supplies with 12" wires attached.

The GPS/PLL board uses a terminal block for power. The GPS lock and LPRO lock signals are available on the boards but the connectors are not installed.

The GPS/PLL board has a used LEA-M8T GPS module. System stability after 24 to 36 hours is better than +/-2E-10Hz at 10MHz, see plot. Equivalent to about +/-2Hz at 10GHz. As the system is operated over time, the output stability should improve. The best I have achieved is +/-5E-11, this is the limit of my ability to measure. If GPS lock is lost, the OCXO output will track the reference oscillator on the GPS module for the duration of the outage. With a good outside antenna, loss of lock should be rare.

This auction includes Rev-B of the LPRO-101 interface board. This LPRO-101 interface board is set up to work with the GPS/PLL board and does not have the reference or 25 turn pot needed for standalone operation. Note: the LPRO-101 interface board in the second picture has the pot installed, the board in this auction does not. This version of the LPRO-101 interface board will block the 10MHz square wave output from the LPRO interface board until the LPRO lock is active. This keeps the GPS/PLL control voltage at mid range (2.5V) until the LPRO is locked, decreasing overall lock time.

The GPS/PLL board sine wave output is transformer isolated and conditioned by a 4th order bandpass filter. The output is adjustable to about 6dBm into 50 ohms. Harmonics and spurious signals are more than 50dB below the output. 

The GPS/PLL board 10MHz square wave output is CMOS through a 47 ohm resistor.

The  GPS/PLL board 1PPS output is CMOS through a 47 ohm resistor. The output is square wave, 20% high, 80% low.

There may be depopulated circuitry on the boards, it is not necessary for operation.

The GPS/PLL board has a 0-5V control output to adjust the LPRO frequency. This can change the LPRO frequency by about +/-25mHz. It can take up to 24 to 36 hours to adjust out the last 10mHz when locked to the GPS.

The GPS/PLL board is configured for a 5V active GPS antenna with power through the coax like those listed on EBAY here: https://www.ebay.com/itm/254926305535.

When using a GPS receiver for timing it is best to use a fixed mount outdoor active antenna with a good exposure to as much of the sky as possible. If limited, try to get south, east, and west. The board can be also be used with a passive antenna or with an active puck style antenna but results may be different than listed.

The UBLOX GPS user interface is available via an on board USB connector if the user wants to monitor satellite reception. UBLOX software (not included) is required for this. There is no need to access the USB during normal operation.

Interconnects are as follows:
Insure that the +24V power supply is OFF.
Plug the LPRO interface board onto the LPRO-101 10 pin connector and secure with screws.
Connect the 24V power connector to the LPRO interface board.
Connect the 24V power connector to the GPS/PLL board.
Connect the 24V power supply (+) to the red wires and (-) to the black wires.
Connect an SMA cable from the VADJ SMA on the LPRO board to the VADJ SMA on the GPS/PLL board.
Connect an SMA cable from the 10MHZ SQ SMA on the LPRO board to the 10MHZ IN SMA on the GPS/PLL board.
Connect the GPS antenna cable to the GPS SMA connector on the GPS/PLL board.
For 5V antenna, install R9 (default), for 3.3V move the resistor to R8. The 3.3V is controlled by the GPS Module.

Turn on the power supply. The GPS should lock first followed by the LPRO about 5 to 10 minutes later.
Once the LPRO is locked, 10MHz square wave and sine wave should be available on the GPS/PLL board connectors.

See my other listing for a four channel sine wave Distribution Amplifier board or an eight channel square wave Distribution Amplifier board that can work with these boards.

The GPS/PLL board is approximately 2.9" by 3.9" with mounting holes in the corners. It is recommended that the board be mounted in the same enclosure with or on the same panel as the LPRO-101. 

PayPal Confirmed Address: PayPal address must be confirmed and must be the same as the shipping address.Returns: All items are sold as-is unless otherwise stated. 

Returns: Returns accepted within 30 days.

Feedback: Feedback is important to me, please email or contact me with any concerns, issues or problems before leaving feedback and give me the opportunity to work things out if needed. I always leave positive feedback after receiving feedback from the buyer, that way I know the buyer is happy and the transaction is complete. 

Shipping: Shipping is to USA only as this board is not RoHS compliant at this time.