In late 2015 I’ve ordered a TelePost Inc. LP-100A Digital Vector Wattmeter at Difona. Because I wanted the dual coupler option, the delivery took quite some time, as it was not in stock. End of January the LP-100A finally arrived. I really like the decent look, ease of use and versatility.
Working as an RF and EMC engineer, I was of course curious about the power measurement accuracy. So I did some measurements in the RF lab I’m working in with a signal generator, a 75 watts EMC amplifier, a dummy load and a Rohde & Schwarz NRVS power meter including a fresh calibrated URV5-Z4 power probe. Unfortunately we have no high power equipment here in the lab, but the measurements give a good indication about the overall accuracy of the LP-100A.
LP-100A Test Setup
This measurements have been done at 14.15 MHz in CW. I also checked the deviation across the classic ham radio bands at 75 watts and there have been only minor variations:
Larry N8LP states on the TelePost Inc. website:
Power accuracy is better than 5% at any frequency from ~1W to maximum, 3% typical with NIST traceable factory calibration
The LP-100A has a per-band power calibration, which is user adjustable. Also the build-in frequency counter is user adjustable. Maybe I’ll adjust that at some point, but for now I’m pretty satisfied with the results.