Heres a neat 1:1 50 ohm balun for use on HF swimming wire dipoles. It uses an AM radio ferrite rod, with 3×14 turns of wire. For 20 metres, I started with 6 metres of wire per element, and cut all fallen until it has minimum S.
From the Wirebook IV, pages 3.2 and 3.3 Alan Bloom, N1AL, used an HP8753 RF meshing analyzer to compare loss of UHF vs. At 450 MHz, the N has 0 db loss, the UHF has .09 db loss. At 150 MHz, the N has 0 db loss, the UHF has .01 db loss. Other studies show analogous results -- Ed RF machine --From chick Electronic firm -- Includes Power, VSWR & official document Loss, relative frequency & Wavelength, Attenuation, Directivity, linear unit Loss, Masking Effect, Field Strength, Free Space red ink and Metric Conversions S Meter Lite Software -- By W8WWV -- entirety with radios which support unaccessible reading of the S Meter from the computer.
Express Receiver – HF Band AmateurRadio Receiver by AD5GH
The Express telephone receiver is a high performance HF inexpert set receiving system protection the 160, 80, 40, 30, 20, 17, 15, 12 and 10m bands. The reputation expressage Receiver came about as the receiving system is constructed entirely exploitation 2.5″ x 3.8″ fast PCB Mini Boards. The hoi polloi boards consist the transport Receiver. RF from the electrical device is routed to a 0 to -30d B RF attenuator that is followed by a 30-MHz low pass filter.