Z3801A

GPS Stabilized Frequency Standard Status

This frequency standard has been in service at it’s current location for several years. Another unit is on site, but it’s power supply has failed so it’s currently off-line. Once repaired, I’ll bring it back online. There is a powered signal splitter in the shack to provide sufficient signal to both units. The feedline is Belden 9913 except for the last few feet on the roof which is RG-58.

 

Updates and Software

This page is automatically updated every 10 minutes or so by the software that is monitoring and logging the units performance. The software creates the performance graph, as well as the one that shows current/expected satellite visibilities. If you want more details on the software, go to RealHamRadio.com Scroll down until you find the information on “GPSCON” software. There is a plethora of great information on the z3801 and similar units on Bill’s site. It’s worth a look! The software can be set to notify you if the link between the PC and z3801 are lost. It cannot tell you if you have a problem between the PC and the web server. I’ve devised a solution to monitor the PC and the connection between the server and PC.

The unit is powered by a homemade power supply that I built from surplus parts. It is very simple design. It is a full wave bridge rectifier followed by lots of capacitance and then a voltage regulator. The power supply has two fused outputs and can power up to two units. The supply was not designed to start two units at the same time but might be able to do it. The reason is that the Z3801A when starting has to bring the OCXO up to temperature. It is in a double oven housing that requires more power during warm-up. So if I have to bring up multiple units, I have to remember to start one unit and let it reach normal operating temperature before energizing the second one. Again there are several great ideas for how to power up the unit on Bill’s site. He even offers a design for a simple, inexpensive power supply.

Uninterruptable Power Supply (UPS)

Additionally, the output of the power supply is tied to a homemade UPS. Since the Z3801A was designed for remote use in telco applications it runs on 48vdc. The UPS is essentially 4 motorcycle batteries in series. The unit can power up the two units for about 50 hours. Normally that would be plenty of time, thought when the Northwest Pacific intertie failed, we were without power for five or six days. I now have a 5kW gasoline powered generator that I can power up the essential household loads. Unfortunately, that doesn’t normally include the time standards. 😉
If the power fails, the UPS will keep them running, but since the PC that logs the performance is AC powered and has no UPS, I can’t monitor performance during the outage. I implemented the UPS from Bill’s website almost verbatim.

The unit has two ovens surrounding the crystal oscillator so that it can hold a constant temperature. The spec sheet for the unit says that power consumption is less than 25watts (nominal). During Start-Up, power consumption is higher I wanted to figure this out so I could build a power supply for the units.

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Why and What for?

What do I use it for? It sees the most use as a time standard for my computer network. I also use it as the source to lock my frequency counter to when I have critical measurements to make. Like on the ARRL Frequency Measuring Test. The reason that I wanted one is for use in weak signal work such as EME (Earth Moon Earth).

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z3801a