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Current projects that are being worked on in the area - please share your interests and find like-minded people!

The G3YZY 6m to 4m Antenna Mod

These instructions, from Howard, G3YZY, explain how to modify a Sirio Tornado antenna designed for the 6m (50MHz) band to use on the 4m (70MHz band).

  1. The new main element length needs to be calculated. Use the online calculator at and enter a frequency of 70.325 MHz.
  2. Cut radials to 1 metre length - not critical.
  3. Cut main section to 5/8th length. You won’t need the top section and the next section down reduced an inch or two.
  4. Replace  the thick tuning coil with new one - 1/8th wavelength of 5 or 6 mm  diameter solid aluminium rod, available online. This needs to be  about 20 inches long. Wind on former, of similar diameter to old coil.

Tune up with an analyser and away you go!

Using the NanoVNA to measure SWR

These instructions refer to Version 1 of the nanoVNA, of which there are a number of variants. Version 2 has a different menu structure. There is a dedicated web site for Version 1 here and Version 2 here.

You may want to check the supplied 50 Ohm load is 50 Ohm. Mine wasn't, so I used a normal dummy load. Other users have had this problem.

Calibration (not essential every time)
(Revised 19:20 3rd Jan 2021)
  1. Reset current calibration state. Select CAL MENU>RESET, and then >CALIBRATE
  2. Connect OPEN SMA terminator to CH0 port and touch >OPEN.
  3. Remove OPEN SMA terminator and connect the SHORT SMA terminator to CH0 port and touch >SHORT.
  4. Connect your dummy LOAD (see note above) to the CH0 port and touch >LOAD.
  5. Connect a dummy LOAD to CH0 and CH1 ports and touch >ISOLN.  Note: If you only have one dummy load load, the CH0 port can be left unconnected.
  6. Connect a cable between the CH0 and CH1 ports, and touch >THRU.
  7. Finish calibration and calculate error correction information, touch >DONE
  8. Specify the dataset number (0 to 4) and touch>SAVE 0 (0 is the power-on/reset default).


  1. Touch the screen once to bring up the menu.
  2. Tap screen and press DISPLAY>TRACE. Touch Trace 1 (Blue), Trace 2 (Green) and Trace 3 (Red) once, so they are no longer highlighted. This will leave you with one yellow line. Press BACK.
  3. Press FORMAT>SWR. You should now see a straight yellow line across the screen.
  4. Tap screen, press BACK twice to get to the main menu.
  5. Touch  STIMULUS>START> (enter desired starting frequency numbers then > M for Mhz, k for kilohertz, G for gigahertz). The menu will close.
  6. Tap screen again and press STOP> (enter desired starting frequency numbers then > M for Mhz, k for kilohertz, G for gigahertz). The menu will close.
  7. Slide the yellow triangle cursor to view SWR at various frequencies, or use the rocker switch on top of the nanoVNA. Do not press the rocker switch, but rock it left or right. The SWR is displayed at the top of the screen.

Comprehensive Guide to Using the NanoVNA to measure SWR
(Courtesy of G3WIE)

PDF file (1.74Mb download)
Original Japanese document by: Satoh, Hiroh (cho45)

Using the TC1 Multifunction Tester

This tester was featured in Radcom, but it seems difficult to find detailed information.
Key features are listed below, and a link to some PDF instructions.

  • Detects NPN and PNP transistors, capacitors,  resistors, diodes, triodes, N and MOSFETs with P channel, JFET, IGBT,  Triac and battery, resistor and capacitor and other components, etc.  
  • Uses a 1.8 inch TFT graphic display(160x128) - Beware of sellers offering a 3.5 inch screen - it does not exist!
  • IR decoder for checking remote controls.
  • Automatic calibration - Short-circuit three test sockets, short press  the multi-function button, and the tester will automatically calibrate.

A video is shown below, and PDF documents with more information and basic instuctions are here (0.5Mb) and here (273K).

Links to videos created by M 6  W V V
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