Clifton Laboratories 7236 Clifton Road  Clifton VA 20124 tel: (703) 830 0368 fax: (703) 830 0711

E-mail: Jack.Smith@cliftonlaboratories.com

This page collects several frequency stability measurements I've made on my Elecraft K2 transceiver. The data covers normal receive/transmit cycles at room temperature and one cold (20°F) to room temperature warm-up.

My K2 (SN 5689) was purchased and built in 3Q 2006 and is thus a relatively late production run, with Elecraft's temperature compensation modifications supplied as original equipment. See Elecraft's "PLL Reference Upgrade" document at http://www.elecraft.com/ for details on changes made in 2003 for improved temperature stability.
 

All data was collected with the same automated setup, as illustrated below.

This card looks like a serial COM port to the computer and as a full bi-directional IEEE-488 port to the device it is attached to. If you need an inexpensive ($120 or so) IEEE-488 adapter, I highly recommend it. It is not fully compatible with LabView and most other software written for a National Instruments card, so if that's your need, take a look at Prologix's FAQ page for more detail. I use it with PrintCapture to grab plotter and print images from several instruments. It can be used with your favorite language to write control programs via mimicking of a standard serial COM port. In this case, I used Terminal to capture the 1992's output data, which I then reformatted in Excel and plotted with Origin 7.5.

I determined the K2's temperature with a Fluke 62 infrared thermometer, measuring the K2's top surface heat sink temperature. The K2's internal PCB temperature lags behind changes to the heat sink surface, as can be seen in the delay between transmit stop and frequency change.

Test data involving transmit cycles was collected with the 40 dB attenuation comprised of a Bird 8323 100 watt, 30 dB attenuator and a Minicircuits CAT-10 10 dB attenuator in series between the K2's antenna port and the 1992's 10 MHz reference output port. Data collected without a transmit cycle used two CAT-20 20 dB attenuators in series.

My K2 resides in my basement workshop, and the temperature during the tests was 72°F ±2°F, relative humidity 32% during the tests. A transmit cycle is made by placing the K2 into tune mode and operating at approximately 50 watts output until the hottest temperature on the heat sink surface equaled 145°F.

The data shows three tests:

• Room temperature stabilized, startup with one transmit cycle after 14 hours of receive operation
• Continuation of the earlier data set, with a total of three transmit cycles.
• Overnight cold soak in 20°F temperature, and then moved into the shop for warm-up measurements.