When I run across something interesting on the internet, I tend to open a browser window and leave it open until I can get back to it. Here are three amateur radio-related links that I’ve had open for a couple of days now. Now that I’ve blogged about them, I can close the browser window.
Get on the sats for $25
Simple 1:1 choke balun
With an M0PZT center insulator, a ferrite core, and a length of RG-58 coax, you can build a simple choke balun. If you have a center insulator with an SO-239 connector, such as the HQ-1 center insulator, you could make this with an RG-58 jumper cable.
btw, this is the first time I’ve seen these center insulators from M0PZT. At £6.00, they seem like a pretty good deal.
How to build a PCB: through-hole or surface mount?
Lots of parts are no longer available in a through-hole package, so increasingly the choice is going to be surface mount.
Dave New, N8SBE says
Pay attention to the ferrite mix. I think for HF use, #43 is common. A lot of ‘hamfest specials’ are not marked, so it’s a crap shoot.
Debco electronics sells known mix toroids, which I used to make choke feeds for my quad antenna. Worked very nice. While I was at it, each feed is 1/4 electrical wavelength (checked with an antenna analyzer) for the band in question. I use an antenna switch that leaves the unused outputs open, so a 1/4 feed translates the open to a ground at the feed point, effectively grounding all the unused loops in my multi-band quad. See http://www.qsl.net/ei7ba/Cubical%20Quad.htm for construction details. I built mine using an old GEM quad, and rebuilt it for 6 bands, 20/17/15/12/10/6 meters, using the formulas/tables shown on the web site given above. My GEM spider gives me a slightly shorter spacing, but otherwise, it is electrically equivalent.