Could the Amphenol 132360 be used for the same purpose? How would it compare to the Mini Circuits item?
Thanks.
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On 2020-12-13 6:52 p.m., Roger Need via groups.io wrote:
Looking through the old messages I see a post by Alan Wolke (W2AEW) where he recommends a low-cost Mini Circuits ANNE-50L+ SMA termination as a 50 ohm cal load replacement for the one provided with the NanoVNA-H4.
/g/nanovna-users/message/14199
The specifications are very good for the ANNE-50L+. The Return Loss (RL) near DC is 55 dB which is a DC resistance of 49.85 ohms compared to the one that came with my unit which measures 50.78 ohms and a RL of 42 db at low frequencies. The ANNE-50L+ RL slowly gets worse as the frequency is increased but even at 1.5 GHz (max for -H4 with factory firmware) it is 42 dB. My interests are with HF and UHF/VHF where the RL is no worse than 50 dB.
There is a belief that low frequency RL performance is a trade-off with high GHz performance. To some degree this is true as you can see in the RL vs frequency plots I attached for the mini Circuits Anne series of terminators.
From the previous thread on this subject some felt that there was no need to be concerned about RL to this degree and the supplied cal kit is satisfactory. That is true if all one is interested in is measuring/tuning antennas for VSWR and to get a rough idea of impedance. But some of us, like me, are mainly concerned with measuring components, filters, baluns, circuit S parameters etc. and we are trying to get the best performance possible from our NanoVNA. I am amazed how accurate the NanoVNA devices can be with proper attention to calibration and test fixture construction.
Roger
