Where ever I operate contest in a multi transceiver environment interferences between the 40m and 20m are guaranteed. An easy and inexpensive way to reduce interferences is to add coax stub filters. Dave, K1TTT has a great website with a lot of useful technical resources. One of them is dedicated to coax stub filters. After building up two sets of stub filters (one in Namibia at V55V and the other one in Spain at ED1R) it’s time to document it.
In untrusted environments like open WiFi Hotspots, you want to tunnel your traffic through an encrypted channel to the internet. Last year Firesheep has proven successfully how dangerous surfing in a public, non-encrypted hotspot can be. A Virtual Private Network (VPN) can also be used to access internet services with IP Address restrictions (e.g. Video or Music streaming services like Netflix, Hulu, or Spotify). In this post, I’ll show you a VPN solution that can be easily set up and used. The tutorial will work with Windows and Mac OSX.
If you have ever dreamed of having your server, then I have good news. It has never been easier! In this tutorial, I will discuss why you want to have your server, how to set up your own Linux (Ubuntu) Server in less than 10 minutes and how to do this for free!
It seems that the exchange of GU74b / 4CX800 tubes in Amplifiers like Alpha91b, Acom2000A, and Acom1000 is more interested than originally expected. In my post on how to replace the tubes of an Alpha91b I explained in depth why it is so important to recondition, to “getter”, the tubes at least 24 hours before any other voltage can be applied. Often amplifiers apply automatically HV and grid voltages which makes them unsuited for the gettering process. My Buddy Matthias, DK4YJ built recently a simple device that makes the heating and testing of tubes much more convenient.
A friend of mine recently was very generous and sent me four used 4CX800 / GU74b which he didn’t need anymore. The tubes were traveling a while and through several non-EU countries. Today the parcel finally arrived. I have already heard wild stories about customs, but I didn’t expect this: Customs drilled holes in two tubes and later opened them with a saw. Check out the pictures.
I’m a believer in true knob and button radio interfaces, and I’m not the only one. A small team, formed around Stu, K6TU developed the Contest Knob, which is now today manufactured by FlexRadio Systems under the name FlexControl. In this interview K6TU reveals the ideas behind the Flex-Control and describes in detail the steps from the design to the industrial production.
In preparation for the upcoming CQWW 160m Contests, my friend Hannes, DK1NO was so kind to give me one of his W7IUV broadband, high IP3 preamplifier. Thanks, Hannes! Without knowing the exact performance data, I ran a few measurements with my Network Analyzer on the amplifier to determine the Gain and its operational fitness. Read on for measurement results and additional notes on how to measure active components.
