Conversion of NOELEC style balun board to 1:1 left readers with a challenge to measure the through performance of the modified balun board. The link grounding the centre tap was cut for this test to float the secondary so that one side could be grounded. This will give almost identical response to the case where … Continue reading Conversion of NOELEC style balun board to 1:1 – through measurement
This article describes a small 1:1 balun for use in measuring field strength using a TinySA Ultra and a small loop antenna. The balun is also useful for measurements using the NanoVNA (or any VNA), eg for measuring two wire transmission line parameters. Materials Some “TC1-1T RF Balun Transformer 0.4-500MHz 1:1CT” transformers were purchased on … Continue reading Conversion of NOELEC style balun board to 1:1
A question of often asked is whether the ‘best’ balun on a T match ATU is: a Ruthroff 4:1 voltage balun (as it often fitted internally); a Guanella 1:1 current balun; or a Guanella 4:1 current balun. The subtext of the question is often that the OM has switched from (a) to (b) in pursuit … Continue reading 4:1 voltage balun vs 1:1 current balun on the MFJ-949E @ 1.8MHz
Voltage baluns are making a comeback for HF antennas discussed the application of a common Ruthroff 1:4 (voltage) balun design to a slightly unbalanced theoretical scenario. This article applies the same analysis to two reported measured dipole cases at 3.6MHz. G3TXQ dipole system at 3.6MHz (Hunt 2015) reported measurements of his dipole antenna system at … Continue reading Voltage baluns are making a comeback for HF antennas – some real antenna measurements
I planned this article to be a Youtube video, but recent behaviors of Google / Youtube give me pause to consider whether or how I use Youtube in the future. So, this article is a simpler presentation of the underlying concepts. For most purposes, users of HF antennas would like the feed line to perform … Continue reading Voltage baluns are making a comeback for HF antennas?
Ruthroff described some baluns in 1959, and which have had continuing application. This article discusses the 1:4 Voltage Balun. Voltage Balun From Definition: Current Balun, Voltage Balun: An ideal voltage balun delivers voltages that are equal in magnitude and opposite in phase. A good voltage balun will approach the ideal condition. It will deliver approximately equal voltages (wrt the input ground) with approximately … Continue reading Simsmith model of Ruthroff 1:4 voltage balun
Seventh part in the series documenting the design and build of a Guanella 1:1 (current) balun for use on HF with wire antennas and an ATU. Design / build project: Guanella 1:1 ‘tuner balun’ for HF – #1 Design / build project: Guanella 1:1 ‘tuner balun’ for HF – #2 Design / build project: Guanella … Continue reading Design / build project: Guanella 1:1 ‘tuner balun for HF’ – #7
Overheating balun cores – an explanation discussed a scenario where an operator reports unstable VSWR after 30s of ATU adjustment. Where the antenna system incorporates ferrite elements, a possible / likely explanation is that loss in a ferrite core has been extreme and raised core temperature to the Curie temperature at which it quickly loses … Continue reading Overheating balun cores – how much power does it take?
Correspondents raise instances of damage to baluns with me from time to time, and there is a steady stream of reports online. One of the very common reports is of something unexpected happening while adjusting an ATU, after perhaps 30s of power applied, VSWR suddenly becomes unstable, changing for some unknown reason, and attempts to … Continue reading Overheating balun cores – an explanation
Correspondents raise instances of damage to baluns from time to time, and there is a steady stream of reports online. The thinking is often “my balun is rated at 5kW, how can I damage it with a transmitter that is only 100W?” This article discusses heat dissipation from a small sealed plastic enclosure. This is … Continue reading Power dissipation of a sealed plastic balun enclosure