A little diversion

I have been working quite a bit on learning and improving my HF operating skills as well as building some antennas for portable use. I am still working on the buddistick but have not been able to get it outside for testing. It is a bit to windy outside today to set it up as I have not worked out the guy wire scheme yet. I decided to try and finish a little project I had started a while back to put together a scanner for the public service band frequencies here in Brownsville. I have two USB dongles with the 820T tuner chip in them and wanted to set them up to run Unitrunker software. I had tried this once before with no success.

My original plan was to do a three way split from the discone antenna outside to allow me to use one line for the panadapter dongle and the other two for Unitrunker. The wiring for this was a little messy so I decided to try and build a 1/4 wave vertical for 865Mhz. This turned out to be easy as the elements are about 3-1/4″ long. I soldered heavy gauge wire to a chassis mount SO-259 connector, one at each mounting hole for the radials and One to the center terminal. The radials are bend down by about 45 degrees to raise the feed point impedance. I am using 75 Ohm coax for a feedline with a SO-259 to F-connector adapter. Only issue building this is it takes some time to heat up the connector flange to get a nice solder joint.


I tested this little antenna using SDR# and it was picking up the signals quite well. I was surprised to even get a strong signal at 162.55 MHz weather radio frequency. I may have to try this out on the air bands as well just for grins. I had much better luck setting up Unitrunker this time. I think I was using the wrong control frequency before. 858.075 MHz did the trick this time. I am going to try a different configuration that uses a SDR# plug-in and see if it provides any better functionality. I think it will allow me to download the available talkgroups from radioreference.com so I can tell who is speaking.


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