VK4ZXI

DIY aluminium washers for cavity resonator In many cavity resonators, the input and output coils are rotatable to adjust the degree of coupling and/or transmission losses. Most mount the coaxial connector for the coil on a large washer, so it can rotate, then use screws to hold it in position. Sounds so easy, but where do you get the washers?? After wasting a few hours in off-line shopping at bolt and plumbing shops, I found that I would have to make them. Working with thin metal sheet is usually not easy. However, I devised a simple technique to quickly make them. Any metal that can be cut by a hole saw or step drill could be used, aluminium, brass, copper, even thin steel, (per my post on using galvanised steel buckets) The photo shows the process. Using the hole saw, cut the first blank. Subsequent blanks are started with the sheet over the hole in the wood made by the first and drilling from underneath (hands away from hole), then cutting the blank from above. Use thr...

Cheap GPS-disciplined 10 MHz oscillator- updated 5/10/2014 This post is for a c heap GPS-disciplined 10 MHz oscillator . It is a work in progress, while the links are still active; life is a work in progress... I had earlier set up a Trimble reference, but they are a bit stone-age , but work well! http://vk4zxi.blogspot.com.au/2014/02/gps-disciplined-clockoscillator.html . Modern Trimble gear is too expensive for my purposes.   Update 5/10/2014: I have the device described here now and it works well, especially the little active antenna, I can get satellites though our tile roof. There is a temperature controlled crystal oven version available. It can access most other GPS satellite systems as well as the USA system.  ($70) TXCO version: UBLOX NEO-M8N GPS GNSS receiver board with SMA: http://www.csgshop.com/product.php?id_product=170 The datasheet for the NEO-M8N: http://www.u-blox.com/images/downloads/Product_Docs/NEO-M8_DataSheet_(UBX-13003366).pd...