The 48^th NEWS VHF/UHF/Microwave Conference was held in Windsor, CT from May 8^th thru 11^th.  This event brings together VHF/UHF/Microwave enthusiasts from around the Northeast and Canada.  They always have an interesting lineup of speakers.  This year there were two presentations that really caught my eye.

The presentation on Basic Light Communications by Paul W1VLF gave a good overview of the subject including an interesting story on how he scavenged 140 IR diodes for his optical transmitter from old tv remote controls when he worked for a CATV company.  Fred K1FMS followed this up with a presentation on the details of his equipment and a series of 940nm (319 THz) contacts he made with Paul at up to 25 miles so far using basic DIY hardware.

The optical equipment consists of simple available components that are mounted on a tripod.  A common transmitter consists of a bank of Infrared LED diodes combined to make a high-power emitter.  A cheap square wave generator powers the LED bank with a simple switch to send CW.  The receiver consists of an IR optical receiver IC behind a projection TV lense.  The output of the optical receiver feeds a trans-conductance amplifier and then a software defined receiver (SDR) like an AirSpy.

Following the presentations Paul W1VLF & Fred K1FMS displayed their equipment and gave a demo.  For more information visit Paul’s YouTube page https://www.youtube.com/user/W1VLF/videos .

I went out on another POTA adventure to round out my goal of 500 contacts a month. This time I trekked out to Prince River Wildlife Management Area in Barre, Massachusetts. The antenna this time was a 53 foot inverted-L design I modified from an idea I found on YouTube.

A commercially-available antenna from Chameleon is a 25 foot telescoping whip that connects to a variety of other stuff they sell for the portable ham radio market. I don’t have any of the Chameleon parts ($$$), but I have a spool of wire($). To an electron, a 25 foot piece of wire looks pretty much like a 25 foot telescoping whip…

The design I ripped off used a 28 foot piece of wire and an alligator clip to extend the whip to 53 feet. I just cut a 53 foot section of wire and put a support loop at 25 feet. The 25 foot section is vertical, and the remaining 53 feet goes out more-or-less horizontally. A number of radials and a 4:1 unun round out the setup. In Barre I was using 15 radials which worked pretty well. The 53 foot length is essentially one of those carefully-selected “random” lengths that, with the 4:1 unun, tunes on multiple bands. I’ve had this antenna “tune” on all bands 6-80, and the contacts were made this day on 10, 15, 20, and 40 meters.

At the site are remains of what must have been a sizeable house. The fireplace is large – I estimate (poorly) that it’s ten or twelve feet on a side, and the hearth looked to be about six feet wide and half that as wide. The foundation was 25 feet or so a side.

One can see that the coverage of the antenna was reasonably good. There were additional contacts in Germany and Spain that didn’t show up in the screenshot.

More information about my POTA operations and antenna “experiments” will be coming up in future editions of the Signal.

73,
John KK1X

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