Thomas Does Radio or Something

In eventual hope for getting on 2.3 GHz, I picked up a pair of very low cost surplus panel antennas originally intended for SISO 2.4 GHz ISM operation. These were likely for WISP or other internet range extension use. I'm going to presume that they're broadband enough to extend down into the narrowband amateur segment, but maybe I'll get the chance to test that before applying much power. Blank, smudged radome of a TP-24-20-18 antenna

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.

What with the ARRL June VHF contest coming up this weekend and the weather being warmer than 12"+ of fresh powder experienced in January, I finished buying and putting together the right PVC parts to hold my Elk 2M/440L5 LPDA antenna stably above head height. It's composed of a cheap speaker stand with the speaker post inverted, 6' of 3/4" schedule 40 PVC pipe, a 3/4" to threaded to threaded to 1" fitting pair, and 2' of 1" PVC to fit the stock bracket of the Elk. Rotation is, of course, of the armstrong type. No additional handle required. Assembled stand setup in the apartment stairwell. 6' of RG-58 for scale hanging from the Elk antenna core (no elements mounted). Gets some decent reach!

In working closer to be committed to actually hacking up a UV-K5, I acquired one, saved its memory config and EEPROM raw read, and popped it open: Simply flipped open on my desk

With the extremely strong solar storm, we went out to a darker park here in Madison. Specifically Picnic Point of the UW Lakeshore Nature Preserve. So many photos to dig through, but here's the choice pick. Meteor trail in Aurora Borealis over Madison, WI There were probably more colors earlier in the evening, but clouds and storms obscured the sky. At the later hours, flickers of color were visible all the way to the southwestern sky and directly overhead.

Being contemporaneous for a new achievement and experience: 6m auroral propagation with a QSO at 5W! With the G5 storm observed before 0Z, I built myself a more durable 6m full-wave loop and set out to experience some new amateur radio. Heading out to a local hilltop with a plan! Initial deployment of the 6m loop on my fiberglass pole for a tuning check and preparation for operating

As previously discussed, the BK4819 simplex FM transceiver chip with specified coverage of 18-660 and 840 to 1300 MHz covers a lot of Region 2 amateur radio bands with generally accepted FM operation: 10 m, 6 m, 2 m, 1.25 m, 70 cm, 33 cm, and 23 cm. The most popular models of amateur-oriented HTs using the chip generally only cover the popular VHF/UHF split with 2m and 70cm (and wide enough filters to support nearby business/public safety bands). How this is implemented varies in cost, complexity, and potential for effective modification. Of course, it's not really a modification if it's an actual product, but more on that further in.

For the QRPer's Field Radio Kit Gallery , this is my KX3 and speaker wire in a camera bag activation kit. This kit is the continuation of the equipment I used for my Maine ATNO expedition and other activities on that return to my parents almost a year ago. Primarily, it's a change in bags and an improvement of the audio connection options for more sustained activations. Writing up this kit for the gallery also will probably be an incentive for further change. With how loosely packed it is, there's space for options! You can see this kit in action on my recent trail activation . The bag packed and ready for an expedition, even if just a little ways away.

With an Elk Antennas 2M/440L5 providing me directional operation on 2m and 70cm and a couple handheld rigs that include 1.25m, I wanted more than just a stock whip to operate with those rigs. Since I have access to scraps of copper refrigerant tubing at the day job from test/prototype systems, I thought it'd be a great material to build with. To put it briefly, the results have been fantastic to start. As initially assembled on the terribly scientific test stand of an empty recycle bin.

The afternoon after my sky picture , I went out to one of Wisconsin's newer POTA entities (Capital State Trail, K-9773) after work to pick up another activation. One of my hunted P2P contacts included a request for a station setup picture, so this is for VA5MUD who was operating from VE-0111. This was a quick activation cut right at 10 QSOs due to the arrival of the anticipated rain. Antenna setup using the trail emergency locator marker as a support for the fiberglass pole.

The Quansheng UV-K5 ( product page archive ) handheld transceiver has been notable in cheap amateur radios of 2023 by using both a wideband FM chip BK4819 ( product page archive ). With support of 18-620 and 840-1200 MHz half-duplex with 6.25/12.5/20/25 kHz channel spacing, this puts the chip in the range of five ITU Region 2 amateur bands (10m, 6m, 2m, 1.25m, 70cm, 33 cm) and spitting distance from a sixth (23 cm). Presumably hitting 4m and the rare 8m would be within reason as well. The easily hackable firmware indicates at least nominal receive capability up to 1300 MHz, though!

I found the sky outside particularly striking last week. Just to get the blog rolling again, I'll put this here as non-radio-related content for your enjoyment. Sky over Fitchburg, Wisconsin on the morning of 2023-10-24. Shot with Samsung Galaxy S10+, unprocessed JPEG.