Orion, Ursa Major, and Scorpius

Tonight, while walking home, I decided that these were probably the 3 most apparent traditional constellations that people could see.

I mean, Orion stands out. I’m not just because some movie production house took advantage of the obviousness. It really is an impressive constellation. Well I don’t know for sure, I am sure that in most civilizations people would have taken the bright stars in Orion and turned it into something that meant something to them.

Ursa Major, is another impressive constellation. Seven brighter stars, all fairly close in angle, and it really does look like some kind of weird handled ladle.

Scorpius looks wicked. I mean, you probably need to know what a scorpion looks like to appreciate scorpions, but the constellation really does have a great resemblance to a scorpion. Shaula, The stinger, it’s perfectly placed. Antares, the heart of the scorpion. Do scorpions have hearts?

Living here in Arizona, and even in California before that, there were plenty of scorpions around. So Scorpius really does remind me of its namesake.

My very first wardriving card!

I got all reminiscy while digging through a box of stuff that was 14 years old. Found the Orinoco Gold Wi-Fi card that was the heart of my first wardriving setup. Smokin’!

In 2002, a few of us at Motorola SPS RF/IF Products (or was it Radio Products?) were fortunate enough to acquire the Lucent Orinoco Gold cards. We experimented with ad-hoc, infrastructure, all at the amazing speeds of 11 Mbps in the 2.4 GHz band. Darren, Dave and I had the cards. Long before Moto even had employee Wi-Fi in its buildings.

Here at my main site, there’s some scattered monthly summaries of how Wi-Fi was slowly taking off in Phoenix. I mapped them each month in an effort to convince our management that Wi-Fi was growing extremely fast, and that we needed to address the Wi-Fi chipset space. Sadly, we never got our act together, not as Moto and not as Freescale.

One weird trick for making the amp behave

Alright. Things are looking much better again. Moved the LNA to its rightful position just 2 m of LMR-195 behind the antenna. Put the FM BCB band stop filter behind the LNA. Since I’m not sending dc up the coax right now, and since the BCB stop filter is in the way anyway, I bit the bullet and built myself a quick and dirty solar charging battery supply for the LNA!

5 w solar panel, purchased a decade ago from Harbor Freight; 8 NiMH AA cells in a series holder; LM2596 buck converter to reduce the battery voltage to 5.0 v; a Tupperware container to hold the batteries and converter. Impressive, no? %^) Let’s see how it survives the night.

Here’s the new block diagram – note the PCR-1000 is on one leg of the first splitter, so it should have no more than about 4 dB additional loss than when directly connected to the coax from the roof.

001 – 100 MHz, w/LNA, w/filter, w/o-3dB-splitter:

001 – 100 MHz, w/LNA, w/filter, w-3dB-splitter:

Here, the added loss from the splitter is apparent from DC to 80 MHz or so. It apparently doesn’t pass low frequencies well at all. Since the antenna is not rated that low anyway, it’s good to get rid of additional interfering signal…

100 – 200 MHz, w/LNA, w/filter, w/o-3dB-splitter:

100 – 200 MHz, w/LNA, w/filter, w-3dB-splitter:

It seems that the splitter has greater than 3 dB additional loss until up around 140 MHz. The aviation band (118 – 136 MHz) is about 7 dB worse than without the splitter. But that’s it. No other weirdness. I can live with this.

Am much more satisfied now. LNA is directly behind antenna. Have a new experiment to see how solar battery charging works out.

LNA unhappy with 10 uH Coilcraft 0805 chip inductor

Today I finally synced up with my friend Doug and collected from him quantity five Coilcraft 0805 10 uH chip inductors. Tiny things. Had little caffeine today, so by the time I’d returned home I was pretty steady.

Brought the LNA down from roof, opened lid, clamped assembly down to bench so it wouldn’t move, put a drop of 60/40 on one inductor pad, and with my TU-10b tweezer I picked up the part and set it in place, then tapped the one end with the soldering iron. It was harder than I thought; the part weighs nothing and has no surface friction with the tiny bead of molten solder, so it instantly moved on me.

After some re-approaching of the problem, I got the part securely attached. Checked continuity, everything looked good! Lid back on. Connected it to network analyzer, and everything did NOT look good. 20+ dB gain above about 200 MHz. The whole 10-200 MHz output level was badly attenuated, and there were strange artifacts in the low end of the spectrum. Removed the inductor and everything returned to normal. Posted a note to the designer over on gpio.com and am awaiting a response. 10 uH at 100 MHz is 6k  ohms impedance, so it should be fine. The LNA was drawing its typical current (~ 160 mA).

Took another identical  inductor and pressed it down on the pads with a plastic tuning stick, and did exactly the same thing as soon as it made contact. There’s something about that output circuit that doesn’t like the chip inductor.



NIST WWV and Canada’s CHU

I have been working on the “long-wire” antenna that’s only about 10′ above the ground, and buried in the oleander hedge. It’s 110′ long, and fed about 10′ from one end. There’s an SGS tuner out there, but it’s currently not active, so it’s kind of hit and miss.

I programmed in the Central East Pacific HF aviation channels, but haven’t heard anything yet on them. With an antenna like this, I think I’m asking a lot.

I also programmed in all the WWV/WWVH/CHU time broadcast frequencies, more as a sounder than anything else. If I can hear one or more of these, that gives me a very rough idea of how well the antenna is working.

Tonight, I can hear CHU (Ottawa, I think) on 3330 kHz, at about -92 dBm. WWV (male voice, so Fort Collins) is running about -71 dBm on 2500 kHz, -93 dBm on 5000 kHz. Don’t hear a darned thing on 10000 kHz. But it is 4 hours after local sunset.

And, while you were asking “what’s the format for the beeps and boops on WWV?” I grabbed this handy-dandy quick guide from their site.

So now you know.

Hey – I think I might just be hearing WWVH (woman’s voice) on 10000 kHz. But the path is really poor.

LNA mounted – time to test!

To recap: I’ve taken the LNA that I purchased from iseeabluewhale on eBay and put it into a diecast aluminum box (purchased 10 of those from wonderco_buy on eBay as well). The TNC pigtails came from my friend Chris’ stash. The other bits and pieces came from the fossil beds of the garage.

Turned out to not be so tricky to get the thing mounted and connected.

Put it up on the roof behind the FM notch, and powered by 4 NiMH batteries.

First test – sweep 100 – 200 MHz and see what it looks like. Hopefully it looks just like the sweep from last night, just 20 dB higher.

100 – 200 MHz Pre-LNA, with filter, from last night (red peak, green instantaneous):

100 – 200 MHz w/LNA, with filter:

No obvious instability or oscillation. All the signals I can hear, like NOAA weather, Arizona DPS, aviation AM, even the residual signals from FM broadcast, all clear and crisp. My my my. Looks like pretty good fidelity.

Now I’ve just got to get a source of stable dc power to the amp! And I like these little boxes…

Adding a ground plane to attach the LNA

Found some 30-year-old double sided copper perf board, cut a small piece to support the LNA in the box. Will solder the LNA to the perf board to mechanically support it and to provide a rock-solid electrical ground plane. Not sure it’s necessary but it looks better!

Pilot holes for connectors drilled. Maybe this time I’m closer…

A *while* later… had to notch out the circuitboard a little bit to allow me to get it in with the connectors already in place. Does appear solid and substantial.

Next, how trim down the LNA board to fit. See you soon!