Thomas Does Radio or Something

One of the follow-up questions on optocoupler bias generation  was if optical LEDs would be a decent candidate for generating a higher voltage output without needing to handle the 8+ volt output from the isolated gate driver photocouplers. The short answer is no, probably not even in comparison to stacking multiple 0.5 V output optocouplers. Energized green SMD LED driving another unit of the same part number 

Over at SignalStuff, there's a new directory of Radio Models  intended to help with handheld transceiver identification and antenna compatibility. Since I've got a small stable of HTs and a desire for another blog post, here are my entries for the database.

Another round of funny enough morning clouds to throw on the blog. Sky over Fitchburg, Wisconsin on the morning of 2025-09-11. Shot with Samsung Galaxy S25+, unprocessed JPEG.  

In an effort to be prepared for figuring out how to work an integrated microwave SDR, I picked up three amplifier modules for 900, 1300, and 2400 MHz. They're all from the same eBay seller and presumably the same factory with matching enclosures, labeling, and design techniques. Lineup of the three amplifier modules (labeled 2.4G 10W, 1250, and 915) with the heatsink planned for future use.

After reading the W1GHZ GaAsFET LNA Bias entry, I wanted to see what the performance of these exposed-base optocouplers are. The concept comes from the IEEE Microwave Journal Application Notes: Photovoltaic Bias for Depletion-Mode Devices in Low-Noise Amplifier Applications (DOI 10.1109/MMM.2022.3226635). It's not open access, so I figured some publicly available characterization data would be cool to share. I have access to a dual-channel precision SMU (source-measure unit, Wikipedia ) and that's exactly what we need to characterize the photovoltaic behavior of optocouplers! Keysight B2902B SMU front panel during a 20 mA input, open circuit output measurement

Being in want of some more surplus-sourced RF components, I picked up a Buker 2H Lockswitch module. It appears to be part of an NMR multi-band interface solution: AVANCE II with DRU TwoBay . Specifically, I have the 750-900 MHz version. And thanks to the university for retaining and publishing these esoteric pieces of documentation. Front overview of the 1U chassis with SMA, N, and isolated SMA interfaces, plus power indicator LED

I've been sitting on my to-be-modded UV-K5 for a while now in hopes of having low-cost access to more bands . In my diversion from this project, others have put together some good work, though at the low end of the range. The ludwich66 GitHub wiki tracking UV-K5 projects covers them on the Hardware_Mods_27Mhz page . The two sets of PDFs were uploaded back in July 2024. Yeah, I'm behind a bit. Let's dive into what's been implemented.

With the QSOs from my trip to California in October, I finally completed the requirements for a long-sought-after POTA award . James F. LaPorta N1CC Activator: Having QSOs from 10 different entities on 10 different band. I was trying to not have only one state (Wisconsin) parks on the list and ended up getting a 3-fer in California that satisfied the 10-band target. So not quite coast-to-coast, but more than just the local parks! Award: James F. LaPorta Award; In memory of N1CC issued to Thomas Murphy WN1C on 2024-11-04  

I went out for the North America SSB Sprint for November 2023 to get a combo park activation and contest participation in. My choice was the north shelter at Governor Nelson State Park ( US-1452 , KFF-1452, wiki ) as an exploration for hoping to operate at this location for the upcoming ARRL 10m contest. Of course, I wasn't operating on 10m given the lateness and band selection for the sprint! And the early sunset meant that I didn't really get the best pictures for the antenna setup since I had to get the antennas up while I could still aim.