Low Pass Filter
Today's experiment is a 10 MHz low pass filter to clean up a square wave and turn it into a sine wave. This comes from the realization that the reference output from my Racal Dana 1992 universal counter is very unclean square wave instead of a pure sine wave. Because square waves are actually composed of numerous harmonically-related sine waves, a good filter can extract just the fundamental tone of interest. Cool, huh?
Why is this important? Let's delve in a bit further . . .
40 dB RF Power Sampling Tap
This is a refinement to an earlier 40 dB coupler that I built in 2013. That first one was taken directly from the May/June 2013 issue of QEX Magazine. Inside, there was an article from Loftur Jonasson (TF3LJ / VE2LJX) about building a simple digital RF power meter. Jonasson's article referenced and built on earlier work by W7ZOI and W7PUA (published in the June 2001 issue of QST).
Homebrew RF Power Splitter
This is a little experiment at building a circuit that seems easy, but may not actually be that simple. I needed 0° power splitter for my 10 MHz precision frequency standard project. I picked up a Minicircuits ZFSC-2-1 on eBay which solved my immediate need, but the allure of experimentation is too strong to resist!
Power Supply Test
Yesterday (8/28/14), I did a lot of testing on the repeater's power supply. It works! And in my usual style, I have lots of data:
Subcategories
Lab Frequency Standard 1
This started as a quest to build an atomic frequency standard based on a rubidium oscillator. After realizing that I could get much better short-term stability and long-term accuracy by building around an ovenized crystal oscillator that's disciplined to a GPS time reference, the project was retargeted.