A newbie wanting to measure a CB (27MHz) antenna with a UHF plug when his nanoVNA has an SMA connector sought advice of the collected experts on groups.io. One expert advised that 100mm wire clip leads would work just fine. Another expert expanded on that with When lengths approach 1/20 of a wavelength in free … Continue reading nanoVNA – experts on improvised fixtures
The D44-22P-01 is a Chinese LED plate rated at 15W and operates directly from 230VAC with an integrated driver. It was purchased to explore the configuration of LEDs with integrated driver, and this driver looks deceptively simple. The chips are JZ1009AE, a LED current driver. The 22 2835 LEDs are 9V LEDs for a string … Continue reading LED plate analysis – D44-22P-01
Fox Flasher MkII and several follow on articles described an animal deterrent based on a Chinese 8051 architecture microcontroller, the STC15F104E. This is an update after several years operation outside, and some in service modifications to improve performance. Above is the original basic schematic. Above is the revised schematic. One only high current LED driver … Continue reading Fox flasher MkII update 7/2019
The Inkbird ITC-308 is a digital heating / cooling controller with two independent outputs for heating and cooling, and using a thermistor temperature sensor. Above is the ITC-308 package. Last update: 16th March, 2021, 2:36 AM
Introduction A recent article questioned the accuracy of measurement of Matched Line Loss (MLL) for a modified commercial transmission line. The published results were less than half the loss of an equivalent line in air using copper conductors and lossless dielectric, when in fact there would be good reason to expect that the line modification … Continue reading Transmission line measurements – learning from failure
A correspondent trying to get his head around old designs was challenged by the Tuned Plate Tuned Grid (TPTG) oscillator in common cathode configuration. A superficial analysis is that the feedback to the grid from the anode via the anode to grid capacitance (Cag) is in phase with the anode voltage, which because of inversion … Continue reading Tuned Plate Tuned Grid oscillator – a simple, but complete explanation
A recent long running thread on QRZ entitled “True balanced auto-tuner” was sure to tease out some pretty woolly thinking… the word “true” was enough to signal the outcome. There are only three words in the title, we can dismiss “true” as a harbinger of woolly thinking, and though people will argue the toss on … Continue reading True balanced tuner
Richard (G3CWI) published an interesting blog article Comparison of groundwave performance of Small Transmitting Loop and Quarterwave GP summarising a recent WSPR test on 40m over 20km distance. This article is a walk through of the expected WSPR receive S/N for the case of the 20mW tx on a quarter wave vertical. 100% efficient tx … Continue reading G3CWI’s ground wave tests Jul 2017 using WSPRlite
Announcement: ic9350 is updated to v1.03 to add support for the Codan 3040 automatic antenna. The ic9350 is protocol converter to permit use a Codan 9350 or 3040 automatic antenna with an Icom radio. Most Icom radios support the Icom AH-4 ATU, so the approach is to design a protocol converter that converts the protocol … Continue reading ic9350 updated to support 3040
David, VK3IL posted EFHW matching unit in which he describes a ferrite cored transformer matching unit that is of a common / popular style. Above is David’s pic of his implementation. It is a FT140-43 toroid with 3 and 24t windings and note the 150pF capacitor in shunt with the coax connector. The popular belief … Continue reading End fed matching – analysis of VK3IL’s measurements