开云体育

AL values are set based on the best guess idea for how many turns will be on a certain sized core. Let me digress a bit.? For coils wound on high permeability cores (think u > 200) nearly all the

I do occasionally just rerun e.g. thru calibration.

Exactly Roger- ignoring the reactive component and not knowing the resistive component - and also knowing the antenna system' complex Z can lead to worse CM. W8 JI, and Owen Duffy, in addition to the

In my opinion the working of a CMC is to stop RF-currents on the outside of the braid, whether it originates from the antenna or from surrounding mostly vertically polarized disturbances. Thus these

Some interesting thoughts on this subject by K6JCA with an extensive reference list on this topic at the end of his blog post.

I had the same problem. Reset needs to be done before calibration. I wonder why the firmware developers just don't do it before starting a calibration. Another NanoVNA "mystery".... Roger

There is some debate on how the measured S21 common mode choke impedance actually effects the performance of an antenna system. Here is one viewpoint by Owen Duffy as food for thought.....

Why? The goal of the measurement described is to evaluate the impedance (L) presented by the CM choke when installed in the feedline. Presuming #14 or #12 wire is used, the DC (not the same as

Hi, Gyula, Thanks a lot for very interesting links indeed. I need a time to digest it. However, just interesting, which readings shows a “big” VNAs in S21 if short both ports with previously

The permeability of most cores can vary (per spec!!) +/- 20%. This variation, of course, reflects on the inductance of each winding. Dave - W?LEV -- *Dave - W?LEV* *Just Let Darwin Work* *Just

Ok it looks like you have to press "RESET" before you can re-do the calibration? I was afraid RESET would clear out all the saved calibrations

I think part of the problem is for some reason when I go into calibration, the "Load" item is highlighted still. Don't know why

There seems to be no narration. Can't you just mute the sound?

Gyula, yesterday all was well and I did some calibrations with my new set of cables, SOLT and FF & MM units to save connections. My results compared to pages 19,20,21 are so-so. Today. no menu. I went

Even when I try to do a new calibration using the included calibration kit (that came with the VNA) it still says "open" is 107ohms or such and doesn't go to infinity on the smith chart properly.

I've been using the NanoVNA for a bit but I've found when calibrating, the "open" value isn't working reliably when using cables or when using extended adapters (like SMA extension for a male to male,

Yes AL values of commercial toroids do vary quite a bit. I have found the need to add or subtract one or two turns to get the correct inductance values. Each mix is designed for a certain frequency

Wouldn't you want to know what the resistive component of S21 is? Dale W4OP

I was just looking into this the last few days to create a range of equipment I have SOL set and pleasantly see this message thread in my email. From my understanding, for above UHF work, the

Hi, I do CMC-measurments by simply connecting the coax outer braid to the center of CH0 and CH1 and then trace 1 on LOGMAG and Channel 1 THROGH, see attached pictures. In my case the CMC is with