Time Based Reference in VK3PKT’s Shack

So over the last 12 months the Twisted Shack of Mark VK3PKT has been getting a lot more test gear. Some of it was from the hamfest, some from people that I know and some from eBay.


I first aquired a 550MHz Freq Counter this is connected to a 10MHz GPSDO timebase to lock it to a known reference. It is then connected to a 10 MHz-520 MHz Marconi AM/FM Signal Generator to give an accurate display of the frequency of the RF Sig Gen.

1PTAX0001Marconi RF SIgnal Generator and Philips Freq Counter 


So I have a lot of my gear, 3 Frequency counters and a Time Interval Analyzer hooked up to a GPS Disciplined Oscillator. This uses GPS satellites to create a very accurate 10 MHz signal to use as a reference for the test equipment.  I also have a Rhode and Schwarz Frequency Standard that outputs 5 MHz 1 MHZ and 100 KHz. I use an oscilloscope connected to both the 5 MHz output of the R & S Standard and the GPSDO to get the FRQ standard on spec.


This scope is dedicated to the job of using lissajous figures to monitor the GPSDO and both the R & S as well as my OCXO Ovenized Crystal that runs off 12 volts and has a small SLA battery to keep it running while taking it from the shack to the car then to a mates shack to calibrate gear. I first adjust the transfer standard against the GPSDO using a Scope and then take it to the required location as needed.

transfer2 transferstandard1 transerfreqFrequency Counter showing Frequency of the transfer standard 

Now when it come to calibrating counters and reference standards I start by using the GPSDO as the Master Standard, this is the one that for my shack I trust the most to be accurate. That is what I feed it into a lot of my test gear as a reference. To check the 5MHz R & S I could just use lissajous figures but I have a bit of gear I picked up dirt cheap on ebay. It cost me 160 bucks delivered and new was over US $8000. It is a Yokogawa TA320 Time interval Analyzer. It measures periods down to picoseconds. Here is a histogram of the the 5 MHz signal calibrated against the GPS 10 MHz signal.


As you can see the range of the window is only 2 nanoseconds, from -1 to +1. The average signal is 199.97958198 over 99.999999 Million samples. The gate time is set against the 10 MHz reference. Apart from setting standards what would you use such a beast for ? Well the manufacturer gives a few ideas with one being connecting it to a hall effect sensor counting teeth on a flywheel of a drag car engine it is fast enough to see a stretched pulse at full throttle if the engine misses a bit. It is also used a lot to measure jitter in optical drives for CD’s and DVD’s in a musical recording studio making master discs.

TA320 with Freq Counter permanently connected to it

PTAX0001Here is a photo of the Rohde & Schwarz Freq Standard and GPSDO mounted in 19 inch Rack, there are four 10 MHz outputs on the back of the GPS that break off to test gear in the lab. One comes to the a hole that was in the front of the R & S that had a broken neon lamp in it and was just the right size for a BNC connection to break out the 10 MHz from the back of the GPSDO to the front panel to make it easy to get to it.