GPS-9700 Locked Frequency Source
The GPS-9700 is a GPS Locked signal source that was designed for the Icom IC-9700 Transceiver to stabilize frequency when using narrow band weak signal modes. The basic EME197 module board could also be used with other Transceivers that use a frequency reference in the 30 to 50MHz frequency range, providing they have easy access to the frequency reference oscillator. The design incorporates a 0.28ppm low phase noise 49.152MHz Voltage Controlled Temperature Controlled Crystal Oscillator ( VCTCXO ) reference. The frequency is amplified and applied to the IC-9700’s internal 49.152MHz frequency reference using a small coupler PC board to mode lock the frequency. Tests indicate that when applying +5 to 8dBm into the coupler board, the IC- 9700 is easily able to be pulled onto frequency. The GPS-9700 module can be used with or without GPS locking, and is much more stable on its own compared to the IC- 9700 due to it being separated from temperature changes within the Transceiver. For high frequency stability narrow band weak signal modes, a high quality low phase noise external 10MHz GPS source is required.
The use of this product does require removal of the Icom IC-9700 bottom cover and replacement of a cable and soldering of the small coupler PC board. This should not affect Icom warantee as No modifictions are required to the Transceiver that could damage it. This also means that when the GPS-9700 is not used, the Transceiver will still function the same as from the factory and be locked to its internal TCXO. The use of the GPS-9700 however will not allow the automatic 10MHz calibration to work as the SMA to IPX cable is replaced and used with the coupler board, but this should not be an issue as manual calibration is still available.
1/ There are no current changes to this Kit.
The pictures below are a final revision so should be carefully followed in construction. Probably the only really difficult part is the fitting of the AD9835. It is very important that the Kit construction notes are followed very carefully with regards to initial testing of the 5v regulator before increasing the voltage to the board. BUY THIS PRODUCT
The pictures below show the coupler board with components fitted to suit the IC-9700. Care should be taken when fitting the small IPX connector as it has to be mounted so that the centre pins connection on the underside of the connector is soldered to the PC board strip line track. When fitting the board to the IC-9700, care should be taken when dismantling the transceivers bottom cover and soldering the board into place. The SMA connector cable on the rear of the Transceiver is removed carefully replaced with a longer cable which is connected to the coupler board instead of the Transceivers main board. This means that the automatic 10MHz calibration will no longer work but it is not required when using the GPS-9700.
The Programming LZ2WSG software can be used to program the Arduino Nano for a single frequency for the AD9835.
The module board is designed to be fitted into a Hammond 1455C extruded aluminium enclosure. The enclosure helps to stabilize the freerunning frequency of the VCTCXO by protecting it from environmental temperature changes. Assembly is quite straight forward but you will require another SMA washer to be fitted onto the RF OUT connector as a spacer before the front panel is fitted. The LED should also be fitted after the front panel has been fitted as it makes it much easier to bent the leads to fit the board before soldering into place.