Adjustable RF Ammeter

This is an adjustable version of my homebrew RF ammeter.

Adjustable RF Ammeter

An old 10Ω, 5mA FSD moving-coil meter was used to display RF current. A discarded plastic box was found to fit the bill for the enclosure.

Adjustable RF Ammeter - Schematic

RF current range is settable from 0.2A to 1A FSD through the 1kΩ screwdriver-slot potentiometer.

Related post: Steampunk RF Milliammeter

_______________________________

Steampunk RF Milliammeter

A vintage 1Ω, 200mA FSD ammeter was there, so this steampunk project was taken up.

To start with, the 1Ω shunt and 30Ω series resistors were removed to restore the meter movement's original characteristics (10Ω, 5mA FSD).

The enclosure emerged from a scrapped multimeter housing and a sheet of acrylic. It was easy to work on the acrylic for the required cutouts.

All parts were available in the junk box.

RF Milliammeter

The circuit was wired up 'dead-bug' style.

RF Milliammeter - Schematic

The meter was then roughly calibrated to read around 500 RF milliamperes maximum.

Output of a vintage solid state 15W CW/AM/SSB rig was successfully peaked up using this meter.

Related post: Homebrew RF Milliammeter

_______________________________