Perhaps the most important skill possessed by an engineer the knowledge of the practical limitations of theory and the theoretical limitations of practice. Here are my notes on some of my projects.
repair notesI enjoy keeping electronic gear going "longer than expected." I'll probably promote this section to the navigation bar soon. But, here are some of my repair notes for radios and appliances.
filtersTod, K0TO, Ford, N0FP, and I, took a brief interest in bandpass filters for SO2R and Multi-Op contest stations. Tod and Ford seemed to have boundless enthusiasm for the project, each producing several prototype filters. I was the one who had access to HP Network Analyzers and some background in filter design. We based our work on W3NQN's filters. Tod and Ford were able to eek some more performance out of their homebrew filters.
- K8GU's Construction Notes [HTML] - In January/February 2006, I finally started building a few more W3NQN filters. These are my notes on the construction, including component substitutions and mechanical considerations.
- Comparison of Dunestar, ICE, and N0FP "Torpedo" filters with an HP 8753D network analyzer. [PDF] - The N0FP "Torpedo" is a beefed-up TX version of the W3NQN RX filters from the July/August 1999 issue of QEX. The strong notch above 40 meters in this filter is due to insufficient coupling in the impedance transformers because multifilar windings were not used.
- Comparison of Dunestar, ICE, N0FP, and K0TO filters on 40 meters. [PDF] The K0TO filter is an RX-only filter based on the same W3NQN topology listed above.
- Tapped-capacitor filter topology. [PDF] A discussion of using capacitors in place of multifilar inductors in W3NQN filter designs. This is primarily an illustrative example relating to the "mysterious null" in the N0FP filters, since there is no coupling.
Update! As of March 2006, Lynn, NO9Z, is also working on a set of W3NQN filters based on the QST articles and the Panasonic capacitors. I hope to post some of his results here, as well.