wythall radio club

Neil G1TZC  describes yet another successful Tuesday Evening Activity at Wythall Radio Club

” This evening we had an outdoor activity to demonstrate the use of the nano VNA tool. The aim of the evening was to demonstrate how we can see what our antenna is actually doing rather than what you think it is doing.

Several members brought along an array of interesting antennas for testing

                                               The test station ready for use

The test equipment was the VNA with the N type connectors. This was my preferred choice only because I find the N type more durable than the SMA. The VNA was connected to a Fusion 5 tablet with a clip on keyboard, running Windows 11. My reasoning is that I find the software easier to use than using the touch screen.

An important thing that many people don’t understand is how to set the unit up for use. Until recently this included me. This next bit is vital!

Once you have selected the device you must set the sweep parameters BEFORE you run the calibrate sequence.

The sweep parameters will give you the lowest hand highest frequency that you are interested in. For the first round of tests we used 1MHz to 31MHz so that it showed the full HF band for people who thought they might have multi band antennas.

Neil (foreground) demonstrates to R-L Mike, Peter and Martin. Phil and Dave G7IBO in earnest conversation in the background

Next is the calibration sequence. Connect the short / open / load adaptors to the port you are using (we used 0). After connecting each adaptor click on the button on screen. There will be a short pause as that calibration is done. This is repeated three times. Then apply the calibrations.

We were looking at SWR so we set both the SWR11 and SWR21, from the dropdowns, as what we were looking at in this instance. As soon as the antenna is connected you get to see the SWR for the entire sweep that you set. The SOTA vertical was resonant at around 6.6MHz and with a quick shortening of the antenna it was retuned to 7.1MHz.

                                        Phil’s mystery military vertical

The military antenna was attached as Phil didn’t know what it was. Instantly on connection it was showing that the it was a 28MHz antenna. We recalibrated the VNA to sweep 25MHz to 55MHz and Phil removed a couple of the lengths that made the whip and moved it down to 51MHz, so he now has two bands on the old bit of military kit.

Martin and Pete also came along with compact HF antennas designed for portable working. Martin left understanding much more about the way his antenna does what it does. Pete liked the confirmation that his antenna really did work as it said on the packet.

Chris works on his impressive 40m vertical.. with a shortening of the vertical wire an impressive SWR achieved for CW operation at the lower end of the band.

It was a very productive evening and already people are asking for a re-run focussing    on seeing how portable VHF, UHF and SHF antennas work.

If you live in the south Birmingham area, please pop along to the Tuesday club night. Sometimes we are doing stuff, other times it is a pint and a chat. “

                               TUESDAY  6TH AUGUST   8.00 ONWARDS ON THE ‘LAWN’ WYTHALL HOUSE.

RADIO ACTIVATION  AS WE TRY THE RECENTLY DONATED  HUSTLER VERTICAL (THANK TOU CHRIS EYO) WITH THE FT857