Z3816A Modification

Posted on Feb 6, 2014

The Z3816A is a GPS disiplined timing source that was manufactured by HP in the middle 90`s. It was intended for use in cellular telephone equipment. It provides 10 output signals through sma connectors on the back panel. 1 PPS - from the 4 connectors on the left. This is signal is based at 0 V. Every second a 4 V positive-going square pulse into

Z3816A Modification
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50 ohms (5V open circuit), 20 uS wide is generated. The 19. 6608 MHz signals are easily divided down to decimal fractions of a second or into standard baud rates. For my purposes, I planned to use the Z3816A mainly to generate time bases for test equipment. The 10 MHz signals are useful for that purpose, but the 19. 6608 MHz signals are not directly helpful. I decided to see if I could figure out a way to modify the Z3816A to convert the 19. 6608 MHz outputs to additional 10 MHz outputs. I assumed these four connectors would need to remain as square wave outputs, but that is ok. Remove or loosen the front panel. Remove the four screws. Loosen the nut on the main power switch. If this nut is left attached but very loose, the panel can be pulled off of the LED`s and rotated. If the power switch nut is removed, the front panel can be completely removed. Remove the main board. Unplug the antenna wire from the main board. Remove all the nuts on the sma connectors on the back panel. Remove all the torx screws holding the main board and lift it out. When looking at the main board, I found that there are a few wire jumpers applied to the board. As we will see later, two of these jumpers are right in the area that I ended up modifying. I don`t know if most Z3816`s will have this same factory rework. If you want to apply this modification to another unit that does not have the same factory rework, you may have to do your own...

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