Postcard from the ISS

pictures of satelliteThis weekend, Russian-ARISS transmitted SSTV images of satellites hand-launched from the ISS. They used a high-resolution mode, PD-120 transmitted FM on 145.800.

I was set up for FT8, but switched over for one pass and captured this image. My process for decoding was suboptimal — I recorded using audacity on my Mac and then later played the audio back to a PC set up with MMSSTV. I didn’t have an attenuator on hand, so of course the sound level was high for the PC input, but was able to drop the gain a bit in audacity. Maybe I traded off a little image quality, but it worked.

This was a low pass (max elevation of about 12.5 degrees) on a side where I have some obstructions — those horizontal lines are probably tall trees —  so probably not the best image I could have captured, but I was just curious if it would work at all.

I’ll be squeezing out what QSOs I can on 17m FT8 through the end of July 4th and will then swap in a 30m element on the antenna for the next couple weeks.

5R8SV Satellite Ops

After I took the hexbeam down, sanded it, painted it and packed it away, I still had a G450 rotor on my hands, so I thought I would try my hand at satellite operation. Over last weekend, I literally lashed together a satellite station — the rotor platform is held to the roof with taut line hitches.

Our house isn’t ideally situated for satellite operation — particularly to the south where some tall pine trees blot out the sky, but in the other directions, the antenna can see down to about ten or fifteen degrees above the horizon.

Continue reading “5R8SV Satellite Ops”

Thanks, Eliakim

Morning antenna maintenance involved an N95 particulate mask, gloves, and goggles today.

I arrived back in Madagascar late in the evening last week after a brief vacation in Réunion. The next morning, I fired up the rig to see what was going on in the CQ WW WPX SSB contest and rotated the hexbeam towards Japan. The rotor control showed movement through about the first ten degrees, and then it froze. I backed off, tried jiggering it back and forth a bit, thinking that perhaps it was just sticking, but gave up after a few seconds because I didn’t want to strain the motor. I walked out back…

… And it was clear why the antenna wasn’t rotating, about a meter and half below the base of the hex beam, the mast had a kink of about 20 degrees, and the hexbeam was lopsided, brushing against a nearby tree. After surviving four cyclone seasons, it appears that the last one of this season, Eliakim, took its toll.

Continue reading “Thanks, Eliakim”

The MMMM Receiver

Prototype construction of the MMMM receiver. The, um, interesting position of the coils is explained below.

The 80m Madagascar Mighty Mite was suffering from “a tree falls in the forest but nobody hears it” syndrome. Eighty meters is a tall ask for Madagascar — there aren’t that many hams in the coverage area, and given local noise, I doubt any of them can hear well on 80m. It would be a long wait for a signal report about the on air performance of the MMM. Clearly, the thing to do was to create a mate for the MMM, the Madagascar Mighty Mite Mate (MMMM).

In keeping with the philosophy of back-to-basics rockbound simplicity, I decided to build an 80m version of the Sudden Receiver originally described by George Dobbs in SPRAT, and reprinted in 73 (October 1991, page 8, available online thanks to the Internet Archive).

Continue reading “The MMMM Receiver”

The Topper Amplifier Revisited

The amplifier built manhattan island style on a copper PCB I thought my 200mW Madagascar Mighty Mite (MMM) would benefit from some sort of afterburner, so I dusted off a project shelved in 2011: the Texas Topper amplifier. I had built based on a design by Chuck Carpenter and kitted by Rex Harper. I ran into a couple problems back then, including some difficulty getting the bias right on the mosfet at the heart of the amplifier. In another brilliant move, I managed to burn out said mosfet by grounding it while trying to get it and its heat sink to fit into a metal box.

Continue reading “The Topper Amplifier Revisited”

The Madagascar Mighty Mite

Finished mighty mite on copper board
The completed (yet unboxed) MMM.

Over the last few years, there have been a spate of postings from homebrewers taking inspiration from the Soldersmoke podcast to whip up various incarnations of the Michigan Mighty Mite, a very simple rock-bound QRPp transmitter. I’m a little late to the party, but here’s my story.

Continue reading “The Madagascar Mighty Mite”

SOTA: W3/CR-003

A boulder-strewn area surrounded by trees. In the distance, the western horizon
Operating position, with view to the west, towards the Potomac River and Virginia.

I was in the Washington, DC area for a day, and couldn’t resist activating Sugarloaf Mountain — it is just too convenient a SOTA peak to ignore. Everytime I’m in the area, I think about going up it, but often summer weather has foiled those plans. Not this time, though. It was a sunny day for my 45 minute drive out from Bethesda, MD to the trailhead.

Continue reading “SOTA: W3/CR-003”

Tropical Cyclone Enawo

This storm is already intense and predicted to hit the north-east side of the island tomorrow morning with hurricane force. For the last three years, we have been lucky with storms tracking to one side or the other of the QTH, but the track for this one cuts straight down the center of the island and should pass near the capital city, Antananarivo. The prediction has been consistent and is now close enough to be sure that we will experience some rough weather in the next few days.

To that end, for the first time, I have lowered the hex beam antenna. I collapsed down the telescoping sections of the heavy duty 10m spiderbeam mast and threw some additional guy lines over the central plate to which the arms attach. The wooden support beam goes two meters into the ground and is surrounded by buried concrete, so I am not worried about the base, but I do expect the fiberglass arms to be battered about. I considered dismounting the whole antenna, but that would have required more manpower than I have readily available, so it will have to ride out the storm.

Continue reading “Tropical Cyclone Enawo”

ARRL INT DX CW 2017

States and Provinces versus number of bands worked.

Conditions over the previous week have been good, so I decided to put in an effort on the ARRL INT DX CW contest this weekend. I knew from experience that I would not be able to work around the clock since the US and Canada are not typically in range in the morning, so I anticipated being able to get some sleep from about 4 am through early afternoon, which was fine with me. Reviewing recent logs and VOACAP predictions, I mapped out propagation paths and figured where I would point the hexbeam, and more or less stuck to that plan. Over the course of the contest, I put in about 23 hours in the chair.

I was effectively limited to three bands: 15m, 20m, and 40m. Ten was almost uniformly dead, and my 40m loop is very inefficient on 80m. Bands faded in and out more or less as predicted including some good spans of working the west coast on long path in the afternoons.

Continue reading “ARRL INT DX CW 2017”