At Baluns – show me the numbers I raised the value of quantitative measurement of the complex common mode impedance of current baluns as a figure of merit for certain antenna applications.
This article shows a simple method of measuring the complex common mode impedance of a Guanella 1:1 current balun using a modern Antenna Analyser.
The instrument used for this demonstration is a Rigexpert AA-600, and its PC client Antscope. Continue reading Measuring balun common mode impedance – #1
At Diamond X-50N #2 at VK2OMD I reported some details of a new antenna at VK2OMD, including some baseline measurements using a Rigexpert AA-600.
This article expands that information with some measurements made using AIMuhf, and gives some contrasts between the two tools.
The AA-600 measurements were made 26/11/2014, and AIMuhf a couple of months later on 29/01/2015. The system measured should have been identical, the feed line is 9.83m of LDF4-50A with N-type connectors at both ends. Continue reading Diamond X50N measurements – AIMuhf and AA-600
My Quiet solar radio flux interpolations calculator has been broken recently, a result of changes at NOAA where they withdrew the observation data on which the calculator was based.
The data remains available on an FTP server, but my web server cannot access it for security reasons, and it would be unacceptably slow anyway. Continue reading Quiet solar radio flux interpolations calculator
I have spent considerable time over the last few weeks trying to salvage something useful and reliable from the wreckage that is AIMuhf and its PC client program AIM. Continue reading AIMuhf – my strategy
The apples have ripened enough and we have picked a small crop.
Mmmm, warm apple and rhubarb (also from the garden) with ice cream.
Loss of Wireman 553 windowed ladder line at MF/HF discussed the matched line loss of a windowed ladder line with 19 strand CCS conductors.
Above, the loss curves from the article
You might look at this and ask “does it matter”, if 10m of this line is used in a G5RV, 0.0075dB/m at 3.6MHz gives 0.075dB loss… that is just 2%, so what.
That ‘back of the envelope’ calculation is incorrect, that feed line section operates with standing waves and the loss under standing waves must be evaluated. If we took the feed point impedance of the popular G5RV to be around 10-j340Ω at 3.6MHz, the expected loss in 10m of Wireman 553 with that load based on the above MLL is 3.3dB or 53%. By way of contrast, my own G5RV uses 10m of home made open wire line using 2mm copper wires spaced 50mm and the loss is 0.9dB, 2.4dB less. Continue reading Loss of Wireman 553 windowed ladder line at MF/HF – does it matter
I had purchased a handy little USB-serial adapter with multiple outputs some months ago, and although it checked out on delivery, the next time I wanted to use it, it just didn’t work at all.
Above, a view of the internals. It uses an FTDI FT232RL chip, and MAX232 and Max 485 for the RS-232 and RS-485 outputs. Continue reading USB – RS232/TTL/485 adapter
I have written several articles recently on matters relating to Small Transmitting Loops (STL), or “Magnetic Loops” to hams (
What of the Hertzian alternative, a small dipole. Continue reading Small Transmitting Dipole
At Efficiency and gain of Small Transmitting Loops (STL) I discussed the use of bandwidth measurement of a small transmitting loop (STL) for estimation of efficiency.
Paul Casper (K4HKX) has built a series of STL which he describes on his K4HKX QRZ page. Continue reading Comparison of two small transmitting loops