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Haven’t bought one yet but I’d like to make sure I get a version capable of the TDR addition. I’ll have to figure out how to add it if necessary after receiving it. Thanks.

I have been using my nanovna SAA2N for months without issues, and I bought it from R&L who is an authorized distributer of legitimate Nanovna's. This morning my issue started after I calibrated the unit. All of my traces were erratic (see attached picture). Smith chart is a mess of zig zags instead of arcs. I tried the following and nothing has fixed the issue. "Reset" and "Reset All" prior to calibration. Tried multiple frequency ranges and trace points. Tried using both cables. Tested the cables for shorts/continuity. Tested all three standards (short, open, load) with an ohm meter, unfortunately I don't have another set to try. Flashed the firmware. Opened up the case and confirmed good solder joints and continuity from the N connectors to the board. Wiggled the connections and nothing changed. Checked again when the battery was fully charged. Also tried using VNA View and got the same results. The unit was safely stored in the case between the last time it worked and now. What am I missing?

A ham friend has an unusual indoor antenna that he uses with a Zachtek WSPR transmitter. He gets lots of spots from the 200mW transmitter (>500 unique band/spotter combinations in 24 hours), and the beauty of the Zachtek is its tolerance of essentially any antenna load (from nothing attached to fully shorted). His antenna is effectively an off center fed dipole, where the two wire legs wrap around the inside bedroom walls, and are of random/different lengths..i.e .just whatever would fit onto the four walls. The two dipole legs are connected to a simple 6:4 turn ratio transformer (approx. 2:25:1 impedance ratio), with the primary side of the transformer attached to a 4 ft coax feedline line to the Zachtek transmitter. I decided to make some measurements of the SWR with the nanoVNA attached to this "creative" antenna setup. The nanoVNA was OSL-calibrated, followed by attaching the antenna feedline to collect data in nanovnasaver software. After collecting the data, I decided to reverse the two dipole legs connected to the transformer secondary, just to make sure I was getting reproducible data. What confused me were significant differences in the SWR/return loss/Smith charts for the two configurations. I am wondering if this simply reflects how non-balanced the dipole is, such that the coax feedline shield (about 4 ft long) from the transformer plays a different role in each of the two configurations. While making the measurements the nanoVNA was dangling hands free while connected to the USB port on my laptop...so the coax shield side would be the same in both cases...and the only electrical difference was in reversing the dipole legs (of differing lengths) connected to the transformer secondary.

I recently wrote a program to renormalize S-parameter impedance. This lets you measure a filter with a 50 ohm VNA even though the design impedance is higher. In the course of testing the program, I needed to plot S-parameters. I searched extensively for suitable viewers, desktop or online. The ones I located were either incomplete, frustratingly awkward, or had bugs. I decided to write my own Windows S-parameter plotter. It's near the top of the following page. See the bottom of the page for downloading instructions. http://ham-radio.com/k6sti/mu.htm The first image compares group delay for two Murata ceramic filters. The next images show the benefit of phase unwrapping. Brian

I've searched through the message list looking for symptoms similar to mine and didn't find anything. I'm somewhat new to this and would appreciate any help you can offer. I've been trying to get my NanoVNA-F (firmware 1.0.5) to show the results of a 40-meter low pass filter I've built. I know I'm doing something wrong here but can't figure it out. The VNA image is calibrated (including pass-thru), set for the range 6.5 to 29 MHz and logmag S21. Shouldn't this give a flat area leading up to the design frequency followed by a significant roll off through the remainder of the frequency range? My setup is very similar to W2AEW's YouTube demonstration of the NanoVNA with a LPF but gives entirely different results. The image is entirely different, with very large insertion loss and a steep area of suppression peaking at 11 MHz followed by a steep recovery. I worried that my filter wasn't what I thought it was so I tested it with a 7 MHz square wave, looking at input and output with the FFT function of my 'scope. The before and after images show several things: (1) the square wave (yellow trace) is hardly a square wave. It wasn't much of one before attaching to the input of the filter but it's definitely loaded and distorted by the filter. (I can live with the distortion in the test, since the filter is supposed to reduce the high freq distortion anyway, right?) (2) The purple trace is the filter output--pretty nice sine wave. (3) The FFT shows a good 40+ db suppression of the harmonics, especially the odd numbers. So the filter seems to be doing its job. There may be some things not right about my testing of the filter using signal generator and oscilloscope -- I'm new at this. For example, the shoulder on the filter output at about 10 MHz is troublesome, but still the logmag S21 output shouldn't be affected, should it? Any help in understanding why my results look as they do would be greatly appreciated. Best & 73, Mitch NK3H

Hello everyone! I managed to brick my nanoVNA H (clone, as I've found later on this forum) and now it is showing a white screen. First of all, I should have read this forum before the purchase and buy the real thing, but the product looked legit at the first glance. Second, I should've made a copy of the initial firmware before I install the new one. But what is done is done and I'm looking forward for a posible solution. Do you know what firmware came with this thing in the first place, to help me roll back? Since it is a sofware problem I imagine it can be done, but the seller didn't provided his support. Thank you! There are some pictures with the front, back and inside the nanaVNA.

Hi, I am trying to get to grips why I am not getting the same Smith Chart results with my NanoVNA as I am with my DG8SAQ VNA. I have got to the stage of trying to make everything as simple as possible. I am using the same connectors, cables and calibration standards. To make things even simpler I am just using a quality HV mica capacitor which measures 442 pf. According to Pasan software this should be 0 -j50 ohms at 7.2MHz. When I use the DG8SAQ VNA I get milli ohms -j46 ohms, which to me is close enough. Using the NanoVNA with an identical setup I get 11 ohms -j49 ohms. Which is pretty useless. What is going on ? T.I.A. Stewart G3RXQ

* RAIN GUTTER ANTENNA on upper HF bands* * * *I've been experimenting with a variety of HF antennas here at my new QTH at Crosslands Retirement Community in Kennett Square, PA. * *I have some space limitations, but live on the first floor of a two-story apartment building.* *Lots of RFI from everywhere inside the building - S9 on 80m and 40m, less noise on 20 and 10m. * * * *I have a 140 ft end-fed wire with a 49:1 UNUN which tunes up easily on 80/40/20m and not so well on 17m/15m/10m.* *This end-fed is horizontal, low to the ground (winds among trees) and is good for high-angle NVIS radiation on 80/40m.* *I use it on the PA NBEMS net (3583 kHz) and on the Mid-Atlantic NBEMS net (7068 kHz) * * * * * *I'd like to get up something with a _low-angle_ signal for DX on 20/17/10m bands. * *But can I keep any HF antenna "hidden"?* * * *What I am now trying is the aluminum _rain gutter_ for our building, vertical for about 20 ft, makes a right angle turn and runs horizontally for about 20 ft.* *The coax attaches at the base of the gutter, near ground, to a 9:1 UNUN with a sheet metal screw into the gutter for a decent electrical connection. * * * *So overall, about 40 ft of thick (painted) aluminum gutter radiating element - in the shape of an inverted L and not resonant on any ham band.* *Lowest SWR around 16 MHz. It looks like it might work out on the 30m band as well (10.1 MHz). * *I have a Palomar Engineering (500W rating) 9:1 UNUN on 50 ft RG8X coax into the shack (closet).* *I have one counterpoise wire about 20 ft long attached to the UNUN ground terminal.* *Then a good manual tuner in the shack to an HF rig for very low SWR on any band. * * * *Here is what I see on my Nano VNA from 10 - 30 MHz: not bad SWR (under 2.5:1) in the shack on 20/17/15/10 meters.* *I'll give it a try over the next few weeks and see if the local noise is more/less on these bands, compared to my 140 ft end-fed.* * * *I'm often running QRP on these bands, CW and digi modes only. * * * *de k3eui barry*