Steve (G3TXQ) posted a graph comparing Cecil’s (W5DXP) measurements of two turns on FT240-52 and FT240-K.
It is interesting to reconcile the #52 curves with Fairrite’s datasheets. A simple reconciliation is to compare results at the frequency where µ’ and µ” curves cross over. Continue reading Attempting to reconcile W5DXP & G3TXQ’s comparison of K and 52 mix ferrites
Among forum experts, there are ready recommendations for the ideal ferrite material (or mix) for a balun, often without knowing any detail of the application.
The ‘magic’ mixes include K. Perhaps they are devotees of Sevick.
Over some years I have searched for manufacturer’s data on K mix, and found only two references:
- Amidon who give a very brief table summarising characteristics, inadequate for RF inductor design; and
- Ferronics who give characteristic curves, albeit in less common format.
Problem is that Ferronics µi is 125 against Amidon’s 290… so their K materials are different.
One has hoped that an interested competent person might have made measurements of some samples from Amidon to give full characteristic curves, it isn’t that hard. Continue reading Ferrite K mix
An Antenna Tuning Unit (ATU) performs a simple but important function in many transmitting systems.
Almost all things called an ATU are simply impedance transformers, and almost always, narrow band impedance transformers (meaning that when adjusted, they achieved the desired transformation over only a narrow frequency range).
ATUs come in a range of configurations, each designed for a specific set of characteristics. Above is the heart of a Palstar AT2K T Tuner, just three real passive components that are fully explained by conventional linear circuit theory. Continue reading What does an Antenna Tuning Unit (ATU) do?
At (Bertelsmeier & Magnin 1992) formulas are given for calculating G/T from Sun/ColdSky Y factor in several Ham bands, and solar flux at 10.7cm. Continue reading DJ9BV & F6HYE G/T formula
DJ3JJ wrote up some interesting experiments with Yagis for 432 EME (Haefner 2010). Continue reading DJ3JJ’s 432MHz EME Yagi article in Dubus 1/2010
EMECalc v9.09 was opened, a model for 1296MHz created, and the “get IPS data” button pressed.
The report shows solar flux at 1296MHz to be 106SFU. Continue reading EMECalc v9.09 reconciliation issue
K5SO published an article in which he reported measurements of Sun noise rise over cold sky for K5SO, W2UHI and VK7MO.
Above is his graphical summary of the measurements. Continue reading Mining K5SO’s measurements of Sun noise
This article explains how to measure G/T using the Sun. Continue reading Measuring G/T
EMRCalc v9.09 contains a facility to fetch a current report of quiet solar flux from an online source.
Above is a sample report. Continue reading Checkout of EMRCalc quiet solar flux report
A correspondent asked if it was possible to calculate the link budget for an JT65 EME path using the G/T worksheet at (Duffy 2014). Continue reading EME path calculation based on G/T