![]() It appears the Nano VNA's reverse detector is inaccurate on my unit. A short reads 1:infinity and a 50 ohm standard reads 1:1.0, both with stable smith charts. An open on the NanoVNA reads 1:2.52, with a stable Smith Chart. I removed the feed line and connected a 150 ohm carbon resistor, which read 1:1.68 on the Nano VNA. I then redid the NanoVNA calibration and got nearly identical results to the first trial using the antenna and the dummy load. To eliminate the cabling, I replaced the antenna with a 50 ohm terminator at the end of the feed line and the result was an SWR of 1:1.12 on the 8753C. To verify, I hooked up a HP 8753C, sweeping from 130-150MHz, did a one port calibration and observed a SWR of 1:3.27 at 146.565 MHz. So, I hooked up a MFJ-259B and it reported SWR of 1:3.5 at 146.565. The output was lower than expected and the reverse power was much higher, Now I understand about the 5% full scale accuracy of the Bird, but still the reverse power was 1.3W with a forward power of 3.7W. When I measure this antenna using the NanoVNA at 146.565 Mhz, the SWR is reported as 1:1.85 This seemed pretty good, so I attached a transmitter and a Bird 43 with a 5W element just to verify transmitter output as I usually do in a new setup. Homebrew tape measure Yagi fed with 25 feet of Andrew C400 and assorted adapters terminating in a BNC female. ![]() Sweeping from 144-148 MHz, calibrated with lab quality standards. My test setup: NanoVNA (black open case, small screen) - purchased in September 2019. Hi, I have read and this question is slightly different than what was described there.
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