Category: tinyPFA

A prototype 50:75 RF transformer

The design is of a 50:75Ω autotransformer using a single Fair-rite 5943003801 (FT240-43) core. Note that this data is NOT for an Amidon #43 core.

The winding is a total of 6t tapped at 5t, wound as two close wound layers. The prototype used a single conductor stripped from LAN cable. The winding configuration is an attempt to minimise leakage inductance for improved broadband performance.

This is unconventional, but then the conventional designs on Youtube etc do not usually have credible evidence of low InsertionVSWR or other performance. Continue reading A prototype 50:75 RF transformer

Last update: 12th January, 2025, 7:16 PM

Screen capture of the nanovna etc using a Python script

I find it convenient to capture the screen from my tiny devices directly to a computer over the USB connection.

I use a script derived from Ho-Ro’s nanovna-tools.

The script emits a png of the screen, and a png of the screen with the colours inverted (for presentation and printing).

Above is a screen shot from a tinysaultra.

The script is published on github: https://github.com/owenduffy/tinydevicecapture .

Last update: 26th November, 2023, 10:46 AM

tinyPFA – new Nanovna-H4 arrived

TinyPFA is firmware from Erik Kaashoek for NanoVNA-H4 hardware for accurate measurement of oscillator and clock source stability.

I was so impressed with the possibilities of the project, I purchased a new Nanovna-H4 v4.3 a couple of weeks ago to dedicate to this application.

Anticipation got the better of me, and I put tinyPFA onto my existing Nanovna-H4 v4.3 to evaluate it, and was not disappointed.

Anyway, the recently ordered device arrived.

Above, the new tinyPFA at work. Continue reading tinyPFA – new Nanovna-H4 arrived

Last update: 5th January, 2023, 8:06 AM

tinyPFA – HP8656B vs Trimble Thunderbolt GPSDO

TinyPFA is firmware from Erik Kaashoek for NanoVNA-H4 hardware for accurate measurement of oscillator and clock source stability.

This article documents calibration and stability comparison of a HP8656B signal generator’s high stability reference oscillator.

Calibration

Above is a screenshot of the tinyPFA with only Trimble Thunderbolt GSPDO input, and after freq A is nulled (colours have been inverted for printing). Continue reading tinyPFA – HP8656B vs Trimble Thunderbolt GPSDO

Last update: 1st January, 2023, 8:37 AM

tinyPFA – a set of Allan Deviation plots

TinyPFA is firmware from Erik Kaashoek for NanoVNA-H4 hardware for accurate measurement of oscillator and clock source stability.

This article documents an experiment to measure the Allan Deviation of several sources:

  • Trimble Thunderbolt GPSDO;
  • Motorola R2009D service monitor; and
  • Rhode & Schwarz SML01 signal generator.

So, to make a two way comparison or three sources, there are C(3,2)=3 difference combinations, and a fourth test to document the instrument noise floor (connect the same source to both inputs).

TinyPFA and Timelab were used to make the measurements.

The GPSDO reference used was a Trimble Thunderbolt GPSDO which is locked. Continue reading tinyPFA – a set of Allan Deviation plots

Last update: 28th December, 2022, 6:42 PM

tinyPFA – first experience

TinyPFA is firmware from Erik Kaashoek for NanoVNA-H4 hardware for accurate measurement of oscillator and clock source stability.

This article documents a first experience with it performing a quite simple operation, calibrating the internal 10MHz reference oscillator of two devices:

  • Motorola R2009D service monitor; and
  • Rhode & Schwarz SML01 signal generator.

The calibration reference used was a Trimble Thunderbolt GPSDO which is locked. Continue reading tinyPFA – first experience

Last update: 28th December, 2022, 6:33 PM