Sunday, January 15, 2017

Added an Arduino controlled Si5351 VFO to the Bitx40

Like, it seems, everyone on the internet, I have added a digital VFO to the Bitx40 board.

The Bitx40 board is a great base for experimenting with a 40m QRP SSB radio.

The code for the Arduino is based on code from AK2B who based it on code from Jason Mildrum, NT7S and Przemek Sadowski, SQ9NJE.

I slightly modified it to use the Etherkit version of the Si5351 library (which can be installed from within the Arduino Library manager).

Other changes were to strip out some things not needed for the Bitx40, enforce 40m band edges and improve the display of the step size a bit. Here's a video of it in use receiving.

I did run into insufficient space on one of the Arduino I had in the junk box but another worked fine. My fork of the code is available on github here. Having done all this, I'm now having second thoughts and am considering doing what Peter VK3YE did and using a ceramic resonator for the VFO.

Saturday, January 07, 2017

Took out the quadcopter this morning

Great to catch up with some real pros this morning Terry and Paul.

The cyclist on the right who you see briefly in this video told us that he'd attempted a height record with a kite. The kite's angle could be remote controlled and got to about 13km of string.

Friday, January 06, 2017

Hearing Peter VK3YE's 200mW indoor loop

I got an email this morning from Peter, VK3YE, who noted that I'm receiving his 200mW from a WSPRLite on an indoor 90cm magnetic loop.

WSPR of course.

Here's the transmitting loop:

Construction is described here.


I'm now using an SDRPlay receiver with their excellent SDRUno software and hearing Peter this morning.

Click on the screen shot to see it in its full magnificence. The trick for sending the audio output from the SDR software into the input of the WTJT-X application (or whatever you use) on Windows is the free VB-Cable.

I've found VB-Cable works better than expensive commercial software I've tried in the past. Note that after changing settings it's necessary to stop and start the sending and receiving software.

Here is a plot of the signal to noise ratio of received spots plotted against time of day over about three days.

It might be that the better S/N in the early hours of the morning is more to do with lower noise from the neighbourhood than propagation.