As much as I love all of the wires up in my trees, I've come to realize that a little real gain and directivity would be nice. However, my trees are really in the way for a a typical tower and a beam antenna, so I am left to consider what resources I have and [...]
Category: Ham Radio
Modeling Baluns and Transformers with NEC Codes
Antenna modelers are often left with a question about how to handle baluns and impedance matching devices when using the NEC codes. Often we just ignore all of the feed nonsense and place the source right on the antenna wire to find the pattern, drive impedance, etc. You can also just reflect the driving impedance [...]
Coax, Connections, Calculations, Coils and CATV Cable
I've been using a spool of RG-6 CATV cable of dubious quality for quite a while as my go-to source of antenna feed line because I happened to have the spool in my junk collection. Using the 75 Ω cable got me thinking about why we care what impedance the cable is and how matching [...]
Practical Antenna Modeling
Here are the slides for a presentation given to The Valley Radio Club on May 3, 2019. The hope is that the slides contain enough detail that the reader could easily build and run the examples in 4NEC2. Practical Antenna Modeling Power Point Presentation Practical Antenna Modeling PDF format slides Using the NEC Codes With Examples [...]
Revisiting the GR5V and ZS6BKW Multi-band Antennas
When I first started playing ham radio, I ran across the GR5V antenna. It seemed that a lot of folks had them, and there seemed to be a fair bit of controversy about how good/bad they were. For whatever reason, I bypassed the design and went to an off-center-fed dipole instead. Now with more experience [...]
Optimizing Multi-Band Wire Antennas
Simple pieces of wire are not the most sexy ham radio antennas, but they are probably the most ubiquitous, if for no other reason than that their cost-performance ratio is very good. When it comes to the lower bands, there is little else that is more practical for most of us than using a wire [...]
An Optimized 20 Meter Vertical Collinear Antenna
After a few months of pondering how to build a simple pull-up vertical collinear antenna, I think I've finally got it! The motivation for such a design is the fact that I have tall trees for a support and can actually pull such an antenna up into the trees to 100 ft. or even higher. [...]
Variations on a Dipole
Here are the slides from a presentation I gave to the Valley Radio Club on August 4, 2017. Variations on a Dipole - Power Point Variations on a Dipole - PDF Antenna patterns are all about interference
Modifications to the IC-745 for the Digital Modes
The IC-745, like the older ICOMs, is built very robustly with parts that you can see without a magnifying glass, and which you can check with standard meters. The schematics are available on-line, the old ICOMs come up for sale on e-bay regularly, and there are support groups on line to help out when problems [...]
Modifications to the IC-751A for the Digital Modes
If you have success with any of these modifications, please drop me a note to let me know your experiences. Update 12/21/17: Added section on upgrading the reference crystal to a high stability OCXO clock. The 30 year old ICOM HF radios still have a bit of life in them if given the chance. I've [...]
