How it works
The SAB6456 prescaler divides the RF input down to a frequency the microcontroller can count. The PIC measures that divided signal over a timing interval and updates the display. Its reference timing determines measurement accuracy.
The original notes specify an 8–20 V supply and a principal input range of 70 MHz to 1 GHz, with reduced sensitivity below that range. These are archived specifications, not fresh measurements.
Original schematic
CLICK TO ENLARGEOn the bench
Keep RF connections short and calibrate with a known frequency source. Limit the input to the prescaler’s ratings; never connect a transmitter power output directly. The original firmware ZIP is available below.
Resources & provenance
Rewritten from the original circuits/msr/r3j19ns_msr005.php page. Component values and historical performance claims have not been independently bench-tested. The circuit figures have had their watermarks removed.
↓ fw_msr005.zipOriginal ZIP · 738 bytesBrowse all surviving downloads →
