Time is short but I could not pass up the opportunity to give a report on some great fun had this morning on 474.5 kHz CW. As reported in the past, some nuances of my Part-5 grant afford the opportunity to run multiple stations within the same local area within a given radius. I’ve used this feature before when performing some of my micro-antenna experiments so I’m glad I made the error when filing my modification last year that resulted in these unintended consequences.
Last November, Steve Parks, KF5RYI, and I did some 630-meter field work using an Altoids tin CW transmitter, Altoids tin amplifier and a short, field deployable fishing pole vertical fed again minimal radials and loaded with a ferrite rod loading coil. The approach was sloppy, but it worked and while signals were weak over a short distance, it was very gratifying to see this project work.
Some weeks ago there was a discussion about setting up a 630-meter station at Steve’s house using existing antennas. With the ET 15-99 NPRM in progress, it seemed like a good time for Steve to start putting together a station for long term use when the band opens under Part-97. Steve has small children so radials and dangerous voltages are just not an option in the backyard right now but the 1-watt amp to even a large loading coil would not be a real hazard and Steve would be QRV after dark, likely after his children were asleep.
Steve’s current antenna is a 40-meter full wave tilted Delta loop hung off his chimney and terminating at fence posts on either side of the yard about 15-foot above ground. He feeds his loop in the corner with quarter-wave transformers on the bands he wishes to use. I like the challenge of loading up odd things when I know I can do so safely so we set out to load the loop as a short, top loaded vertical with base-resonating coil and a single radial placed along the fence line. It’s literally cobbled-together junk… but it worked!
The vertical section is very short, in fact, it is coax that connects near ground level on the “hot” side of the coil and feeds the corner of the loop.
The point of contention all along has been the straight key. On our original outing, the key had some mechanical issues that made sending miserable. I have since fixed those problems and Steve did a very nice job controlling the key. A keyer is in the works so that the paddle can be used. Steve reported that the KX3 was doing a nice job decoding his sending so that is just another validation that his sending was excellent. In fact, I have the audio of Steve’s side of the QSO below. Note that my recording set up does not pick up the side tone as I am keying so you are hearing a one-sided QSO:
Steve was S9 using the E-Probe for receive with varying degrees of signal level using the other receive antennas on site. I am very impressed with the probe, even over the short distance we were working.
I suspect this set up is a keeper and will develop as we go forward to include a better antenna and more power and attention to safety will be key. What was so cool about this project is that it felt like I was 8 years old again sending Morse on my 49-MHz walkie-talkie… Those were the good old days..
Tune down to 474.5 kHz CW (USB receive passband) sometime. You never know who you might hear down there…