At VK1AD Bi-Quad antenna construction I’ve had a hoot-of-a-time building 23cm antennas for SOTA and portable field ops. 🙂
“It’s time to cut my signal losses..”
For sometime I have used a 1 metre length of LMR195 coax feed line between the 2.5 watt 23cm transverter and my choice of antennas. Due to the feed line length this option introduces losses in both transmit and receive signals. Weak or marginal 23cm received signals are attenuated by feed line losses. In the picture below you can clearly see the feed line length, yes you are right it’s too long! (Mt Gillamatong 19 Nov 17)
It’s time to cut my signal ‘losses’ and move the transverter to the top of the tripod. This option permits the full extension of the tripod to a height of 1.4 metres above ground level, every millimetre gained helps.
Sunday 31 December 2017…its New Years Eve and I have nothing on my plate! Starting with a tripod mount for the 23cm Bi-Quad antenna, also known as a double-quad antenna, I have also spent the afternoon fabricating a small platform for my SG-Lab 23cm transverter.
First let’s look at the the Bi-Quad antenna mount
Camera top plate – I purchased two standard top plates on eBay. Remove the 1/4 inch screw from the center of the plate.
Tripod head – top plate receptor in the vertical position
Mount the spare top plate to the rear of the 23cm Bi-Quad antenna. Do you like my nifty teeny-tiny G clamp?
Top plate secure at the rear of the Bi-Quad by two 3 mm screws, washers and nuts
Bi-Quad antenna fitted to the tripod head – it’s a neat fit.
Construction of a Transverter Platform
In the picture below you can see the tripod head locking knob has space behind the knob flange – Let’s be clever and make use of the space behind the knob and the flat surface of the head. 🙂
Homebrew double-sided copper clad PCB platform – I love fabricating stuff, useful or otherwise! You are not restricted to using double-sided PCB, you may have other materials on hand such as sheet aluminium. Go ahead explore the junk box.
Transverter platform secured by the tripod head locking knob – cool 😉
23cm Transverter and 6el Yagi antenna – LMR195 feed line is now 50% shorter at 500 mm
23cm Transverter and Bi-Quad antenna – For now ignore the feed line length, I will make up a 200 length of RG58 Cell Foil.
That’s my ‘New Years Eve’ afternoon of fun playing amateur radio antenna construction! I will test the B-Quad tomorrow from South Black Range, 40 km south-east of Canberra.
Post update: 6 February 2018
Construction and assembly of a new 200 mm feedline between the transverter RF output socket and the Bi-Quad antenna socket.
You have my permission to copy the design and build your own. 😉
Happy New Year to all and have a safe time playing SOTA in 2018 🙂
73, Andrew VK1AD
Published: 31 December 2017
Last Update: 12 March 2018