nanoVNA - first scan, IMAX2000

[Klondike Mike]

Yeah, I know I am late to the party with this device but I got one now and my first antenna scan is for my old school IMAX 2000 vertical. Its one thing to know it is very broad-banded when it comes to a CB antenna but to see a graph of results is another. My first thoughts were "is this correct?" when viewing the SWR graph spanning 25-31Mhz. Its been 40 years since I last studied a Smith chart but here we go again ...

 

[sp5it]

Nice dummy load.

 

[nomadradio]

A dummy load that radiates. Just ask the neighbors about their surround sound setup.

73

 

[brandon7861]

Even a resistor across the feed point would not cause the abrupt flattening of the SWR curve seen here. This is a result of the VNA being out of calibration.

The little c* on the left shows that the unit is not calibrated. When calibrated, the little c turns to a capitol C. You need to calibrate that for the span and points you have set.

Any time you change the start, stop, span, points, or output power, you will need to recalibrate (OSL).

 

[Cable Guy]

 

[Klondike Mike]

I did get an earlier sample which looks more realistic. Although, I did rush my calibration procedures. I must have missed something. I'll try again.

 

[Klondike Mike]

Finicky little device. I didn't miss any steps during my first calibration. Re-run and saved the calibration this time. Also ran the nanovna windows app and got these results displayed below. This app labeled the Smith chart axis and it then made it easier to interpret. It also allowed for more data points than what is allowed with the built in software. Smith chart study review over.

 

[Alexis Mercado]

Now, those results are way better, more realistic. I had an IMaxx and worked very well. From 1-10, I give it an 8. An aluminum antenna with radials, I give it a 9 because radials help diminish common mode interference ( can be resolver with a common mode filter ). It’s is a little heavy also. I wish I had one. Many people call it Dummy Load , but that Dummy Load radiales very well for what it is. Not the best antenna but it works. Anything antenna is better than no antenna. I had mine avobe a 4 element antenna.

By the way, nice little gadget you have.

 

[Klondike Mike]

Dummy Load?? Antenna? or just me? Whatever. As NomadRadio pointed out, this dummy load radiates into the heavens. See map below for contacts made last cycle.

 

[Lost Ram]

I have great luck with my Imax 2000, it has the ground plane kit and balun at the feed point. Also makes a great vertical for 15 meter too.

 

[sp5it]

Dummy Load?? Antenna? or just me? Whatever. As NomadRadio pointed out, this dummy load radiates into the heavens. See map below for contacts made last cycle.

That proves only how good was propagation at the time.
Nothing else.
Mike