On Sat, Jan 25, 2020 at 01:08 PM, <cosbug@...> wrote:
Could someone advise if these SMA terminators are good ?
I've done a resistance check at DC using multimeter and it's shown 68 Ohms (too high by me, should be lower).
Secondly, I've attached to VNA (properly calibrated with other known good 50 Ohm SMA) and the result is:
1. At frequencies lower than 100Mhz SWR is 1.3.
2. In 1Ghz range has significant capacitance impedance.
The item is rated DC-18Ghz TRM-2444-M0-SMA-02 (specs https: www.mouser.co.uk/datasheet/2/643/pi-CCS-MW-TRM-2444-M0-SMA-02-1312942.pdf)
Am I doing something wrong or terminators are defective ?
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Constantin from your attached photos you have a reason to be suspect. The low cost terminator that came with my NanoVNA-H4 has a return loss of over 40 dB up to 1 GHz, and the Midwest Microwave terminator in your photo is showing a return loss of 20 dB at some frequencies. That's pretty poor and definitely outside the specifications of the device.
I have come across similar Midwest Microwave terminators at swap fests and I cherry pick them using the NanoVNA I always carry with me. The sellers aren't very thrilled because they are left with known subpar terminations on their table while I walk away with the in spec devices.
- Herb
