Micoammeter | Hackaday
If there is one instrument that radio enthusiasts and other radio enthusiasts covet, it is the venerable Bird 43 Thruline power meter. The useful RF tool has hardly changed in the nearly 70 years since its introduction, and they are built like a tank. This makes Bird counters highly desirable, and therefore quite expensive, whether new or on the trade-meet circuit.
But radio amateurs are nothing if not ingenious, and are building a homebrew version of the Bird power meter (in Portuguese; Google translation tool at the bottom of the page) as Brazilian ham. [Luciano Sturaro (PY2BBS)] done is a good way to get your hands on one. Allowed, [Luciano] had a head start: a set of spare lines, which is the important part of a Bird power meter. The machined metal part is actually a section of air-insulated coaxial cable that the RF signal passes through on its way from the transmitter to the antenna. A “slug” is inserted into the tuned line cavity to sense RF and couple it to the counter electronics; the slug can be rotated to measure RF moving in either direction, allowing the user to determine the amount of RF reflected from the antenna system.
[Luciano]The counter version is true to the rugged construction of the original, with a solid steel case that mimics its classic lines – the case even sports the same color scheme and a sturdy leather carrying handle. There are some changes in the electronics, and the movement of the speedometer itself is different from the original, but overall the “Buzz 50” is fantastic. We especially like the detailed nameplate in homage to Bird.
The thing about Bird – and Bird-like – counters is that slugs are like crisps; you can’t have just one. Curious about how these slugs work? Check out this slug repair project.
[Featured image of Bird 43 Wattmeter: Martin RF Supply]
Thanks to [Niko Huenk] for the tip!