QROP Meter: Variations

Display Meters

The two 10-LED displays on the front panel take up a lot of space, which QRP operators might dislike. There are ways to conserve space.
• LED Bargraph Display: You can use 10-LED bargraph displays (like the Radio Shack 276-081 model) instead of the 10-LED displays. However, this requires precision on placing many components as well as the ability to drill a neat rectangular hole in the chassis for the display.
• Smaller LEDs: You can save front panel space by using smaller LEDs. If you use smaller LEDs spaced closer together, you will need tiny labels. I prefer the 5mm LEDs due to the wide availability of black rubber LED holders for that size.
• Analog Panel Meters: Several people have suggested using analog panel meters with needles in them. This saves space by eliminating the need for the microcontroller, 20 LEDs, and 2 PC boards. This also conserves battery power. Needle meters also have the benefit of better readability in bright sunlight. However, analog needle panel meters require drilling a hole at least 1 inch wide (too big for a Unibit) in the chassis. The hole saws at Home Depot are to only be used for drilling holes in wood, not metal.

Power Range

Ultra High Power Version

A higher power version of the QROP Meter would have more QRO capability at the expense of QRP capability. It would need more turns for the secondary windings to minimize the insertion loss. The cores would have to be much larger (in terms of both inner and outer diameter) to accomodate longer windings without excessive capacitive coupling and to be able to dissipate more power.

QRPp Version

A QRPp version of the QROP Meter would have more QRP capability at the expense of QRO capability. The insertion loss of the QRPp version would be greater than in the regular version but not terribly significant. Most QRP operators will also wish to use one of the space-saving suggestions discussed earlier. QRP purists will substitute BNC connectors for the SO-239s that I prefer.