When operating contest in a multi transceiver environment interferences between the 40m and 20m are guaranteed. An easy and inexpensive way to reduce interferences is to add coax stub filters
In this article, author examine stresses placed on common-mode chokes (aka baluns) as hams use/abuse them, examine the efficiency of simple dipole multi- band antennas and their feed systems. Stressing a Balun.
Finding the the best ferrite material for a common-mode choke. How to create efficient ferrite cores and how to measure them
This article demonstrate how to build and mount a 40 meter loaded dipole using basic materials. This antenna reduce the overall length of an HF dipole through the use of loading coils.
Optimizing the Performance of Harmonic Attenuation Stubs
FTDX-9000MP + HDSDR + Ham Radio Deluxe. An IF Based Direct Sampling Panoramic Adapter for the Yaesu FTDX-9000
The Belgian Air Force Amateur Radio Association sponsor of BAFARA Award