Testing-Device for GU74b / 4CX800 tubes

It seems that the exchange of GU74b / 4CX800 tubes in Amplifiers like Alpha91b, Acom2000A and Acom1000 is of 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 which makes the heating and testing of tubes much more convenient.

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Customs break my tubes (4CX800 / GU74b)

A friend of mine recently was very generous and sent me four used 4CX800 / GU74b which he didn’t need anymore. The tubes where 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. Checkout the pictures.

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Flex Control – Interviewing the Developer

Image of FlexRadio FlexcontrolI’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. Download the MP3 or subscribe in iTunes to my podcast!

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Building and measuring the 2el 160m Array

Last weekend we spend quite some time to prepare our contest station ED1R for the upcoming CQWW 160m contests. The biggest task was the installation of a 2el parasitic Array of two verticals. During the installation I took the time to document the measurement results. Find them with my (preliminary) conculsion in this blog post.

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W7IUV Beverage Pre-Amp (2N5109)

In preparation of 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 it’s operational fitness. Read on for measurement results and additional notes on how to measure active components.

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2el Vertical Array for 160m

In CQWW 160m we are planning again a serious participation. This time we want to errect a 2el vertical Array for 160m towards the US. In this post you will find some detailes regarding our unique situation and some design thoughts.
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HC2/AL1O qrv from Ecuador

 During my stay in Ecuador I was able to operate two days under my US Callsign as HC2/AL1O. Special thanks to my host Alberto, HC2AQ who offered me his shack. Within two days, 1700 QSOs found their way into the log.

 Read on for pictures, online log & QSL information.

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