LA2YUA – RF and related projects

In this article I'll cover the design and construction of a high performance segmented capture film scanner, made from an off the shelf 3D printer, 3D printed parts, a Raspberry Pi HQ/GS camera, Raspberry Pi 5, and a high performance industrial lens.

Spoiler warning: A future article will cover how I replaced both the camera, Pi 5, and lens with better though more expensive options.

A different style of writing than most previous posts, I try to decipher why digital cameras didn't show up before they did, what forces made them appear, and just for fun: a look at what electronic cameras could have looked like in 1980.

This article is essentially a "well actually" to the completely unfounded idea that "Kodak had a digital camera in 1975 and chose not to make it because they wanted to sell film". This is of course untrue, like most other anecdotes are when you look into them. Ruin the joke with this one weird trick (knowledge).

Do note that I consider electronic cameras to be a better definition for this purpose, specifically we know that digital stills cameras didn't show up until the early 90's but electronic cameras were around in the 1930's as analog video cameras.

The WM8804 is a now obsolete but still available S/PDIF transceiver that is kind of mid but can be made to work ok for some use cases.

The FCS AMP headset is a tactical communications headset made by Chinese manufacturer FCS. It appears to be heavily inspired by the Gentex AMP series of military headsets.

Following the previous entry, the PCB's for the early summer 2024 assemblies have arrived. First out is the Falcon II KDU PCB's, which replace the original PCB while reusing some of the key components.

The original Tri PRC-152 I purchased in 2023 was not a very good radio, with the biggest issue being a very limited radio with very poor audio.

This is a summary of the current work up to summer 2024, with future entries to be added as I go. Realistically this won't be a finished design before mid 2025.

This is my collection of SWR measurements of various antennas I've bought, partially just to keep them somewhere I can find them.

This article will likely be updated as I acquire new antennas to test.

This article covers the Harris Falcon II KDU, P/N 10511-1300-03 and the associated cable and KDU-adapter P/N 12065-7100-02.

This is an overview of my efforts to re-cap and fix a connector issue with the Macintosh IIfx Astec manufactured power supply.

Some notes on old Macs, started in late 2023. Published in 2025 with some notes. After writing this I acquired an iMac G4 (ca. 2003, 17") that has become my main retro Mac. I also found a cheap working PowerMac G5 that is a future work in progress.

Quick post, yes they work, and one fell apart so I took a picture.

The OCXO card is a somewhat standalone reference oscillator made for the 3021N receiver. This card was finished in late 2022.

Note that this part of the series is published out of order, at the time of first issue this PCA has not been integrated into the radio, but a copy of the PCA has been integrated into a 19" rack unit.

The TRI(iumph Industries) AN/PRC-152 two way radio is at first glance a rather silly device, a clone of the extremely capable and expensive Harris AN/PRC-152 (Falcon III) software defined hand held radio.

Is it worth the money at all?

The Racal Acoustics RA5000 "Raptor" is a military-grade hearing protection/headset, in this article we'll be looking closer at the RA5000/1/1025 model.

Red Hat Enterprise Linux and the closely associated CentOS Stream 9 remove a lot of legacy kernel modules from their kernels. This seems to also include removing sources from their distributed kernels.

I wanted to add the scsi/bfa driver to support Brocade Fibre Channel adapters, this is mainlined but not part of the RHEL kernel sources.

This is a followup to the previous ADF antenna system article, and details performance measurement of the BFU550X based cascoded TIA.

The King KA-42B ADF antenna is a neat little 3-in-1 antenna-pod for aircraft. With some minor^[0] effort it can be used as a pretty good HF reception antenna.

^[0] for certain definitions of "minor"

A followup to the previous NAGRAFAX article, this details how I fixed the automatic phasing circuitry, and has some detail pictures of the electronics boards.

The NAGRAFAX is an early 1980's weather-fax printer, sold as a kit along with a weather-fax FM receiver and intended for marine use. I picked up this unit for $10 at a local auction (first and only offer, surprisingly).

The RF Section or 1st Converter consists of the pre-amplifier, first mixer, and first IF filter in the receiver signal chain. This is typically the most important part of the radio since it determines the sensitivity and selectivity of the radio.

This card was finished in late 2022, at the time of initial publication it has not been integrated yet.

The 3021N Synthesizer is a very complex part of the original radio. It's almost sad to replace it, but I needed the room to fit new power supplies. The synth was designed in the fall of 2020.

This is part of a series covering the 3021N communications receiver. This part covers the Demodulator, and was the third part of the receiver that I replaced with a modern expansion. The demodulator card was finished in the middle of 2020 (I wasn't too busy).

This is part of a series covering the 3021N communications receiver. This part covers the DSP, and was the second part of the receiver that I replaced with a modern expansion. It replaces the Audio Amplifier PCA. This card was designed in late 2018.

This is part of a series covering the 3021N communications receiver. This part covers the Scan Tune Logic PCA, and was the first part of the receiver that I replaced with a modern equivalent, in the middle of 2018.

This is part two of a series covering my extensively modified ITT Mackay Marine 3021N communications receiver.

This article covers various details on the chassis and the signal path. More details of the various cards are given in later articles covering their replacements. The work covered in this section took place between 2017 and 2021.