Recap of EOSS-090

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Post Flight Equipment Report

by Mike Manes, W5VSI

Hi Folks,

I got the EOSS-90 payloads back from Larry K0ANI today (5-May-05) and checked out the parachute, ill-fated DF/cutter beacon and the AE0SS-11 APRS module:

The parachute was delivered like dirty laundry. Fortunately, the lines had not tangled. The burner did its job, but it was detached from the wire yoke at the 'chute apex and the burner connector was still made. Not a problem, but normally the burner returns still tightly taped to the yoke. It is a good idea to un-tape the 2-pin Molex at the burner on recovery to prevent unnecessary accidental burner activation, battery depletion and a fire in the back of someone's SUV.

The AE0SS-11 module was fired up to download the Location Track Register (LTR) log as usual. But this time, the KPC3+ came up asking for an asterisk to set baud rate - a sign that it's BBU RAM has been corrupted.

It was, and I had to do a hard reset to restore serial comms with the TNC. This unfortunately also wiped the LTR memory, so there's no way to fill out Rick's cumulative log. I restored all TNC parameters from a former dump file, and the unit came up working fine in flight configuration, except that the analog readings (batt, baro and temps) were way off. This is symptomatic of an analog signal to the KPC3 microprocessor going above the supply rail voltage. So I suspect that all that Schpitz und Schparkung from the death throes of the DF/cutter on the 7.6 KV line probably propagated down the moist line and created an ESD type of upset in the KPC3. The solution is to replace the KPC3+ miroprocessor chip - DigiKey and Jameco carry 'em for about $10 / pop. I'll get two.

Despite my fervent hopes to the contrary, the old workhorse DF/cutter is totaled. There aren't even enough intact components to part it out. Apparently, the top of the package contacted the neutral line, and the 300-ohm twin lead matching section of the J-pole touched one of the hot phase lines. The fault current fried the conductors in the twin lead, melted the center pin on both halves of the BNC, arced from the shell of the BNC inside the package to the case of the DJ-C1, traveled up the 5V power harness for the radio and into the Basic Stamp board, and then thru the harness feeding the connector for the cutter relay cable. The power connector inside the DJ-C1 vaporized, and a number of SMT components in the vicinity got hot enough to melt the solder holding them to the board before a trace vaporized. The ground leads in the power and audio harnesses also melted. The DTMF decoder chip blew its top, letting out its vital smoke, and 5 pins on the PIC processor on the Basic Stamp cracked or vaporized, as did two tantalum electrolytics. The BNC shell and nut looked like they'd been hit with a welding torch, and the 3-pin cutter cable connector unsoldered itself from the board on the top of the package.

100% burned toast - except that one of the two LiSO2 D cells and the N cell for the BSC1 still had plenty of poop - and the PostIt Note showing flight readiness was just smudged!

I guess the good news, aside from the outrageously successful flight for UKy's Big Blue 3, is that the K0YUK-11 beacon didn't fib this time, despite some problems being copied by ground stations. I guess the audio grunge is still there, despite retrofitting a new TinyTrak 3 beacon generator.

The NOAA timed cutter got shut off before it fired, making it good to go for the next plastic flight.

Merle has proposed that we replace the DF/cutter with a clone of the K0ANI-11 beacon using a controller designed built and donated by Bob N0TI. If Bob can pack in time-slotting so we can reuse freqs in place of the rapid beaconing below 20K' in descent, I'm inclined to agree.

Still need a replacement Alinco DJ-x HT and a GPS engine, though.