Got RF test kit to play with NanoVNA from Banggood: RF Demo Kit NanoVNA RF Tester Board Filter Attenuator for NanoVNA-F Vector Network Anaylzer. I selected this RF Demo Kit NanoVNA over another quite similar RF demo kit because this kit was cheaper and looked better.
This RF Demo Kit is specially designed for RF Network Analyzer learners. It’s what I needed to learn how to use NanoVNA well and learn more about RF circuits. This RF test kit contains totally eighteen types or RF circuits, among which eleven types are single-port networks, and seven are dual-port networks. All the RF circuits on the board are terminated to UFL connectors (depending on the circuit one or two UFL connectors). The board came with two UFL – SMA test cables to connect the board to NanoVNA.
The board is equipped with three well-performing (open-short-load) calibrators which the operator can use to perform calibration with on the VNA before measuring. Calibration is a very good idea to get accurate measurement results.
RF Demo Kit NanoVNA RF Tester Board Filter Attenuator for NanoVNA-F Vector Network Anaylyzer product page has following description:
- PCB board in size of 10 x 10cm
- Vector network analyzer learner tool
- RLC series and parallel circuit 1
- RLC series and parallel circuit 2
- 33 ohm resistance, SWR=1.5
- 75 ohm resistance, SWR=1.5
- BSF ceramic notch filter, center frequency 6.5MHz
- BPF ceramic filter, centre frequency 10.7MHz
- RC series circuit
- LC series circuit
- Homemade low-pass filter, 3dB bandwidth 400MHz
- Homemade high-pass filter, 3dB bandwidth 500MHz
- Short-circuit calibration circuit
- Open-circuit calibration circuit
- 50 ohm load calibration circuit
- 10dB attenuation circuit
- 3dB attenuation circuit
- Can be used with NanoVNA-F to measure 6.5M ceramic notch filter
- Can be used with NanoVNA-F to measure homemade low-pass-filter, 3dB bandwidth about 400MHz
1 x PCB RF Tester Board
2 x 20cm Adapter Cables
The board says that it is designed for NanoVNA-F, but I figured that there should not be any problem in using some other NanoVNA model. When I ordered this kit, I got the original NanoVNA. But later I received NanoVNA v2 that I did most testing with this board. The measurement results on this page are made with NanoVNA v2.
There is a Smith chart diagram on the backside of the circuit board:
This tester board came well packed with all the necessary leads to connect it to the board. This is excellent for educational purposes. It looks like a good board for learning about the use of the NovaVNA test unit. The build quality seems to be very with clear screen printing on the PCB to help with use. It looks to be worth the wait and the money. It is excellent for demonstrating and checking NanoVNA.
For low and high pass full default to 900 MHz scan range for NanoVNA is OK and gives good results.
With many circuits that showed different Smith chart images on the board, it seemed that the drawing on the board did not always match anywhere closely to the drawing. It took some time to figure out, that to get shapes on most circuit drawings to match what I see on NanoVNA screen, it is a good idea to check scan range from 50 kHz to 150 MHz. If I go higher than this stop frequency I get all kinds of strange shapes after when I want to get. If I go lower max frequency I don’t get full shape on the screen.
I am not the one that has found this limitation, from kit discussion:
In Test field 8 the inductor looks like to have nominal 470 nH.
If you accept a tolerance of +/- 10 % = 423 – 517 nH,
the usable frequency range is measured to 3.4 – 126 MHz.
Above 394 MHz the inductor becomes capacitive.
To get best results the tutorial posted to nanovna discussion group has some useful notes on testing:
Please note this, two steps must be performed before testing:
Step 1. Connect the two 20CM SMA to IPEX adapter cables to the NanoVNA-F machine.
Step 2. Recalibrate the machine using the 13 Short, 14 Open, 15 Load, and 16 Thru circuits on the test board, and save the parameters in 0.
There is a full tutorial at http://deepelec.com/rf-demo-kit/ and wiki page at https://groups.io/g/nanovna-users/wiki/RF-Demo-Kit-use.
This test kit is a very good idea. But there are some things that could maybe be improved. The UFL connectors on the board are very small. Little bit hard to see and use. And they feel fragile that they might not last very long. The micro coax plug is named U.FL/IPX, 50 Ohm, about 2mm diameter. For more details see on https://en.wikipedia.org/wiki/Hirose_U.FL. On the RF characteristics those connectors seem to be good, but the on the mechanical side they do not seem to be a good choice for this kind of test kit. Excerpt from Wikipedia page: “Female U.FL connectors are not designed with reconnection in mind, and they are only rated for a few reconnects (approximately 30 mating cycles ) before replacement is needed. The female U.FL connectors are generally not sold separately, but rather as part of a pigtail with a high-quality 1.32 mm doubly shielded cable, which allows for a low-loss connection.” It seems that the problem is the connector used on that is totally unsuitable. It is not
designed for repeated connections. Even the original manufacturer of the device, Hirosose, rate it at 20 connections/disconnections or *Durability* the number *30*. This means that the number of plugging cycles for an U.FL plug is a *minimum of 30*, with a *good probability of more*, if you handle it *careful*.
Please note that according to manufacturer you should use a special tool for removing them. This tool is made by Hirose, who designed the U.FL connector. Unfortunately it is *more expensive* than the *RF Demo Kit*. You can use a 1.0 mm wide flat screw driver for extracting. Up to now it works fine, if you press the cable down with your finger,
while you are levering with the screwdriver.
Every cheap similar looking connector is going to be some variation on that, and I suspect that they do not have longer designed service life than the original connector. I think you can expect problems sooner or later. If you handle the U.FL connector *careless*, you will have sooner or later a *problem*. If you plug and unplug it many times, you can expect to get problems. There are 25 connectors on the board, on 18 Test fields. So, if you test and document each Test field once, including calibration, you are still under the number of 30 cycles. I personally don’t think they will last long in the hands of a ham trying to learn, or demonstrate it to others.