Power Supply on Dhiru's Notebook

Digitally Adjustable RF PA Supply

Sat, 20 Jun 2026 00:00:00 +0000

Baby QRO Switching RF amplifier for HF

A new generation of the Baby-QRO switching amplifier targets 25W to 50W of RF output for FT8 and other FSK modes.

Goal

The Baby-QRO amplifier already has a very useful RF power control knob: the PA drain voltage. A bench supply works for experiments, but it is not the right answer for a digital beacon or transmitter stack. We want the MCU controller to set the PA voltage, and therefore the RF output power, in software.

The best power supply for FieldOps

Tue, 06 Jan 2026 00:00:00 +0000

This short article describes a flight-safe power supply for FieldOps.

Component List

Simply get these:

USB QC/PD AFC trigger decoy board (9V)
USB QC/PD AFC trigger decoy board (12V)
USB QC/PD AFC trigger decoy board (15V)
Xiaomi Pocket Power Bank Pro 10000 33W

This one does 9V, 12V, 15V and 20V without any problems.

OR

A 65W USB PD power bank - not needed for 5 to 10W QRP FieldOps

Testing Small Power Supplies

Tue, 18 Feb 2025 00:00:00 +0000

I found this 60W Electronic Load to be quite useful for testing small power adapters and supplies.

While it is possible to homebrew an adjustable electronic load we recommend getting this electronic load module or a better-but-costlier one like the UNI-T UTL8212+ electronic load.

Observations

You can stress-test power supplies using this electronic load quite easily and conveniently.

It turns out that the Orange branded 12V 2A or 3A adapters from Robu are of really poor quality. The output voltage drops to less than 2V when the load current is increased to around 1A. This is NOT the first time that the Orange branded stuff has turned out to be of poor quality. In the end, you get what you pay for.