This design is about a clone of a clone. Following the footsteps of the WellBrook and the WellGood in this article, here's my version: 'The WellFlex Magnetic Loop Amp'!
In my article about the design of an RF RX front-end for the Yaesu FT-221 R, I had promised to revisit the extender I had created for it. In this article, I will provide some further information on that
Read more: Extender / Riser for the Yaesu FT-221 RD FT-225 D FT-301 D FT-625 R/RD and others
After obtaining my radio amateur novice license in 1977, a transceiver was of course immediately needed. It became the Yaesu FT-221 R. A 2-meter all-mode transceiver that, with its specifications, mechanical construction, and modular design, stood miles above everything else available at that time. A beautiful device. However, I had to part with it quickly. Since my true passion was on the shortwave bands, I immediately started working on CW to obtain my novice license. A Kenwood TS-430 S came into play, and the FT-221 R was sacrificed.
But as it goes with true love, the regret remained.
Read more: PA3AJR - RX RF Board for the Yaesu FT-221 R / FT-225 RD
Traditionally, modules such as GPS and AIS communicate with a serial protocol such as RS232 or RS422, whether or not packaged in a virtual COM port over USB or Bluetooth. That principle, of one producer supplying "hard-wired" data to one consumer, has its limitations. This becomes immediately clear when several customers have to be served or sensors of completely different nature have to work together. And, finally, it lacks a constact factor around which things can be organized in time. A marketplace where supply and demand of data come together, enrich each other, and remain available. An MQTT broker acts as a spider in the web and takes care of this. How to get from AIS via NMEA -> JSON -> Wi FI -> MQTT -> Node-Red -> both in every corner of the hobby space and in the wide world? That's what this story is about.
The AIS receiver described in this article is an update to an earlier version that revealed some issues in the print layout. Since I had to place an order for some other PCB projects anyway, I let this corrected version run along and also took the opportunity to add an extra Si4362 (or Si4463) to the design for dual channel simultaneous AIS-receipt.
Read more: AIS-receiver with two Silabs Si4362 | Si4463 chips and STM32 processer
About seven years ago I designed an information system for law enforcement along Europe's waterways and seaports: AQUATRACK. I then equipped the remote receiving stations with a AIS receiver OEM module from SRT Marine Systems. An excellent product. The phenomenon of AIS fascinated me so much that I was curious if I could make a building block as a hobby project for a fraction of the cost. A search on the internet led me to a nice initiative, the dAISy project which turned out to be based on an EZRadioPRO ISM Band receiver chip: the Si4362 from Silicon Labs and a simple 8-bit MSP430 processor from Texas Instruments. Because I am a little more comfortable on ARM processors and also have the development tools for it, I'd rewrote the source code for a Cortex M0 chip, the STM32F042K6 from STMicroelectronics to be precise. I also made some print circuit board designs for this.
Read more: AIS-receiver with Silabs Si4362 | Si4463 radio chip and STM32 processor
It must have been in the early '70s that I became interested in data transmission over radio. My school for Electrial Engineering in Amsterdam (the ETS, a great school) supported my enthusiastic and gave me two Siemens T37 telex machines. Those things weighed a ton, and it was a hell of a job to get them going again, but after a lot of fiddling with audio filters and discriminators, I finally knew the converting alternating tones on the shortwaveinto legible writing. And vice versa! "RYRYRYRYRYRYRY CQ CQ CQ de PE1BOS" A little later I got access to a beautiful sky-blue Siemens T100S Telex, complete with punched tape writer/reader. After that it became a green teletype video display unit and a IBM EBCDIC keyboard that I converted to ASCII and - later still - the Apple II+ with its plug-in cards and various TNCs for AMTOR, FEQ and AX25.
Silicon Labs provides a range of attractive receiver and transceiver chips in a QFN20 package for telemetry applications in the sub-GHz range with its EZRadioPro series. Additionally, complete modules equipped with this IC can be found for a low cost, notably on platforms like AliExpress. In the latter case, these modules typically feature the Si4463 or the somewhat outdated Si4432. For home automation applications operating at 433 or 866 MHz, I usually opt for the comparable RFM69 from HopeRF. However, what sets the Si4463 apart is its vast continuous frequency range (142-1050 MHz), including coverage of the VHF band, and the fact that it includes the maritime AIS channels (161.975 and 162.025 MHz).
Read more: An alternative matching network for the SI4362 | Si446x LC-Balun at AIS frequencies.
Building on the work of PA0NHC en LZ1AQ (and as a kick-off in this blog) a design for a broadband magnetic loop antenna amplifier. It consists of two printed circuit boards. The first for the actual amplifier, and a second, as an RF/DC splitter placed near the receiver. I moved a year ago, which roughly coincided with my retirement. Two reasons to pick up my old hobby of amateur radio again after years. It would have been no different at my old house, but what immediately struck me once I had installed a dipole antenna was the extremely high interference level. Apparently a sum of all solar panels, power line adapters and LED lighting drivers that are commonplace today. All in all it produces a quite interesting radio spectrum but pretty unusable for HAM radio. All this misery didn't seem like the most appropriate reason to honor all my new neighbors with a first visit. Before saying goodbye to a once beautiful hobby, the aim was a last attempt to find some useful (FT8) signals in this huge mountain of QRM / EMC / EMI / RFI.