Spring VHF Sprint

Setting up for a pleasant spring evening for the  70 cm VHF Spring Sprint. I bagged 16 points, which isn’t too shabby considering I used a magmount antenna stuck to a mixing bowl for the contest (it’s on the top of the patio umbrella). Most of my contacts were on SSB, which was cool because this was my first time using that mode on 70 cm.

Operating Position for Spring VHF sprint

April ISS SSTV event

For the ISS SSTV Event (which was irritatingly not on the ARISS page this time) I only managed to snag one decode (see below).It’s not too bad a decode for just aiming the antenna on the trunk of my car at the approximate angle of the pass and recording the audio coming out of the speaker with my phone. I decoded the audio later using MMSSTV. Hopefully next time I’ll have a better setup.

Challenges Involved in Designing a Linear MOSFET Driver Stage

In the process of designing a linear driver stage to use as a a load, I came across this thread on the EE stackexchange detailing one guy’s design process and lessons learned doing this exact thing.

I’ve ended up using the STP75NF75 because it was the part that didn’t crater during testing. Since most MOSFETS are designed as switches making them operate in linear mode takes some doing.

The whole post links to the various threads that the author was asking questions in, and he has all of them annotated with lessons learned. It’s a quality post and interesting reading in its own right, and is worth reading even if you never want to go through this particular design exercise.

Oddball TL431 circuits

I came across this circuit in the “Typical Applications” section of the datasheet for the On Semiconductor version of the TL431 programmable voltage reference. I think you will agree that it’s definitely not “typical”.

Phono stage built using a TL431 voltage regulator

That’s some old skool Forrest Mims III out-of-the-box shit right there.

Continue reading Oddball TL431 circuits

December ISS SSTV event

The December SSTV Event from the Russian MAI-75 experiment in the International Space Station was not nearly as successful for me as my previous attempt, but I did manage  to snag a few decodes.

I used a Signalink this time instead of the generic $3 USB sound card I used last time, and despite some pretty awful QRM I was still happy with the results.

Continue reading December ISS SSTV event

SSTV from Spaaaacccce

As part of the 20th anniversary of amateur radio on the International Space Station (ISS) the crew broadcast a series of Slow Scan Television (SSTV) images from the Russian crew module. After several failed attempts (mostly due to my laptop’s sound card sucking) I managed to receive and decode this image:

Continue reading SSTV from Spaaaacccce