M0UAW's Blog

 Season's greetings to one and all. I've been fascinated with GPS and GNSS in general for quite some time now, it feels rather miraculous that, for only a few pounds, I can buy a module not much larger than my thumb that will reliably provide my position anywhere on the planet to within a few metres by receiving signals from flying atomic clocks several thousand miles above my head. I've probably got far too many GPS receivers but recently someone posted an offer of free for the cost of postage receiver modules to the GQRP mailing list and it was too good an offer to turn down.  A few days later some nice little Leadtek modules arrived, complete with coax pigtails. As well as the modules, there was a zip file with pinout for the 1mm (?) pitch connector on the underside and a datasheet for the module itself. While they're quite old, they have a SiRFStar chipset which is a decent performer and I've always found them to be reliably fast to get and hold a fix.  Unfortun

If your Baofeng USB charger base never goes green to indicate the battery has reached full charge, this may apply to you. Another indication of the problem is the LED stays solid red with no battery inserted, it should flash alternate red/green. I recently bought a Baofeng which was supplied with a USB charger which is convenient but even when I forgot to unplug it one night and left it on for 2 days it never showed 'green' and checking with a multimeter showed the battery was still under 8V (*never* leave Li-Ion cells/batteries charging unattended.) Turns out the USB cable has a built in boost converter to bump up the 5V to something high enough to charge a 2S 7.4V pack. Unfortunately the boost converter in my USB cable only bumped it up to 9.2V and the reverse polarity protection diode (circled red) in the charger base was wasting 0.8V of that so there's no chance it would ever reach charge termination voltage of 8.4V   A quick google showed the mains powered chargers com

 Place holder for GQRP SCD Digital VFO Post   The chip shortage has struck down the Teensy 3.2 which was used in the GQRP Digital VFO here: https://www.gqrp.com/suddenvfo.htm   Obviously that's a problem.  However, there is light at the end of the tunnel, the Teensy 4.0 is pin compatible so could be a drop in replacement.   I downloaded the 'sketch' and tried to compile it, which failed with what looked like potentially simple to resolve errors and a *lot* of warnings about unused and uninitialised variables. The information below shows the changes I made to the V0_13 sketch and get a successful compile.   Compiled for Teensy 4 using Arduino IDE: Version: 2.1.0 Date: 2023-04-19T15:31:10.185Z CLI Version: 0.32.2 Errors with unmodified sketch when compiled for Teensy 4  "Sorry, i2c_t3 only works on Teensy LC and 3.x.  Use Wire for Teensy 4.0, 4.1, MicroMod." To fix: Change every instance of i2c_t3.h to wires.h In:  SCD_2021_V0__13.ino Si5351.h Si5351.cpp To mop up s