I have a nice off-center-fed dipole (OCFD) antenna that is my mainstay for multi-band HF work, but I would like to understand it better. With a wire antenna tied to trees it is not a simple matter to quantitatively determine the antenna's radiation pattern experimentally. One way to get a handle on this is to compare [...]
Early Spring Volunteer Salad
It's early Spring and times are changing quickly. Although not quite officially Spring yet, the weeds are greening up in the garden. That means that we get fresh salad again! I just planted some flats of lettuce starts, but no need to wait for them if you can grow the right weeds. My favorite for this [...]
EPA’s Proposed Imidacloprid Exposure Limitations are Not Strong Enough
Our comment letter to EPA follows below. OPP Docket Environmental Protection Agency Docket Center (EPA/DC), (28221T) 1200 Pennsylvania Ave. NW. Washington, DC 20460-0001 Re: Pollinator Ecological Risk Assessments: Imidacloprid Registration Review EPA-HQ-OPP-2008-0844 To whom it may concern, We would like to offer some comments on the regulatory endpoints that are proposed in [...]
Comparing RTL-SDR and IC-751A Receivers Using JT65 & JT9 Signals
Once I had the RTL-SDR radio working as a pan-adapter for my IC-751A, I quickly became interested in seeing what I could do with all of those signals that were apparent on the SDR radio's waterfall. My first goal was to see if I could receive the complete JT65 and JT9 signal band, with [...]
RTL-SDR Pan-adapter using HDSDR with the IC-751A
There is little doubt that the RTL-SDR tuner dongle radio receivers are the hottest new thing for the amateur radio experimenter. Re-purposing the $10 tuner dongle to be an extraordinarily wide-band software defined radio is the subject of countless internet articles and videos. Here I am adding my experiences to the crowd. What I will describe [...]
Antenna Comparisons using JT65 & JT9 Signals along with NEC Models
True understanding of a problem is confirmed when one can validate theoretical model predictions with measurements. It is too easy to believe pretty pictures that modeling programs produce, especially when making meaningful measurements is so difficult. In this article I try to take the bull by the horns and see how close I can come to [...]
Comparing Receivers with Digital Mode Signals
I entered second heaven when I got my second radio. My original 32-year-old Icom IC-745 got placed on the back shelf when the new 29-year-old Icom IC-751A arrived. As much as I enjoyed the old IC-745, I was after a little computer control, and the 745 predates the idea that people use computers. The 751A, [...]
The Off-Center-Fed Dipole Antenna – Design
There are a few ways to build multi-band HF antennas. These include multiple resonant dipole arrays, trapped dipoles, resonant loops and the off-center fed dipole, OCFD. I'm going to look at the OCFD because it is relatively simple to construct, yet gets quite decent performance. I also am fortunate to have some nice tall trees [...]
Ham Lingo
Broadcasting's use of abbreviations and obscure notation started with the original radio-men, when every character required some pain to transmit. Today's tweeters and texters have invented their own slang for much the same reason, but without the long linguistic history that accompanies radio lingo. When you first enter the ham world, you have to cross the language [...]
Using NEC2 for Antenna Feed Design
When I jumped into the radio game with my new old Icom IC-745 transceiver, I really had no idea what I was doing. I knew I needed an antenna, so I went to a 1990 ARRL Handbook and found the "Loop Skywire" antenna which seemed like the one for me. The one resource I have [...]
