The parasitic Lindenblad, that is. I wrote in a previous post about how I was gathering the parts to build the parasitic Lindenblad antenna for 70 cm that appeared in an article in the February 2010 QST magazine. Since then, I’ve actually managed to build one of these beasts, and for what it’s worth, it even looks like the one in the picture in the article. My first trial with it on a good pass of AO-51 was less than impressive, though. For this trial, I used my Kenwood TH-F6A connected directly to the antenna with a three-foot section of RG-8X coax (to minimize the effect of feedline losses, which can be appreciable at 70 cm). There were moments when I had good copy on the satellite, but they were few and far between. I was a little disappointed, but I wasn’t ready to give up yet. Knowing that the antenna, being more-or-less omnidirectional, didn’t have much gain (especially compared the the handheld Arrow Antenna yagi I’d been using), I wondered if a preamp might be necessary.
I consulted with the smart guys on the AMSAT-BB mailing list, and the general consensus was that I would indeed need a preamp for best results. And then I read the last paragraph in the QST article:
On the downlinks, a low noise (1 dB NF) preamp mounted at the antenna was employed.
Duh. So, last week I ordered a 70 cm low-noise preamp kit from Down East Microwave. I’m looking forward to assembling it and trying it out as soon as it arrives. And while I’m waiting for it to arrive, I’ll be trying to repair my Samlex SEC-20 power supply. It went kaput last week. Luckily, Samlex tech support was kind enough to send me a schematic, parts list, and some troubleshooting info (let me know if you’d like a copy).
At any rate, I’ll update you on the Lindy and the preamp as soon as I have something to say.