For some years I have used Ceramica muffin fans for low noise and long life. They use a ceramic bearing which is quieter than ball bearings, but longer life than sintered bronze bearings which dry out.
In the last month, I have replaced three Ceramica fans that have failed, one with less than a year’s service and two with less than one month’s service. Continue reading Review of Ceramica ceramic bearing fans
AS/NZS 2272.2 sets out in Appendix E a method for calculation of near field strength of antennas, citing ANSI C95.3—1973 as authority.
This article comments on application to antennas other than those with a circular aperture. Continue reading Estimating near field strength with small antennas
An opportunity presented to measure the loss of a sample of JSC windowed ladder line. The line uses single core #18 CCS conductors and is equivalent to products sold under various proprietary names. JSC Wire & Cable is now known as Seminole Wire & Cable, and this is their 1318 product. Continue reading Loss of JSC ladder line at 160m
I attempted to decode APRS on 147.175MHz, most traffic being received from two fairly local digipeaters (VK2AMW and VK2RHR). Continue reading The extent to which APRS works is often an accident
I built a X450 quadcopter (X450-02 quadcopter (21/05/2014 build) which proved to be difficult to tune, principally the Level control loop, though there were issues with Roll and Pitch. Continue reading A quadcopter tuning story – symmetry is important
In a QST column in 2008, a correspondent asked the question
… I have the ladder line terminated to double coaxes that run about 12′ (4m) inside the house to an antenna tuner. Should this pair of coaxes be grounded at one end or both ends?
The Doctor gave a detailed diagram (above) and his advice was… Continue reading Spoiling balun action with ‘shielded twin’
Some four months ago I sent VK3FI in Mildura a QRSS keyer to try on his 600m beacon. The keyer hardware and message content are described at Simple Morse beacon keyer for VK3FI on 600m.
Above is a capture with Spectran received at my location in Bowral tonight 760km east of VK3FI, QRSS3 on 473.000kHz (well perhaps 2Hz higher, Dial freq 472.2kHz USB for the above display). Continue reading VK3FI QRSS on 473kHz – 19/06/2014
Martin Ehrenfried (G8JNJ) conducted some interesting experiments on a small transmitting loop.
The loop above is 3.45m perimeter of LDF4-50A Heliax, and uses the full length of the Heliax as a stub for tuning the loop to 5MHz. Continue reading Thermograph of small transmitting loop
I have been concerned at slowly degrading performance on my web sites, coming to a head with migration to WordPress (this blog) about six months ago.
To improve performance, I have migrated all content to a new hosting service on Godaddy’s latest cPanel hosts.
It is a substantial amount of work, and I think everything is working properly. It is certainly much quicker and consistently quicker (at the moment) on the WordPress application.
Though I have taken care in specification of character sets, it appears that special symbols have been trashed in the migration. I have done some global search and replaces and think I have found and fixed all (or most) problems. Credit to the Search Regex add-in.
The Double Bazooka seems to have popped up on several fora recently, QRZ, eHam and VKLOGGER.
The Double Bazooka employs a pair of coax stubs as a device for compensation of feed point impedance, extending the VSWR bandwidth, principally to reducing loss in the feed line. Continue reading Double Bazooka magic