CobWebb Balun Box

The CobWebb is a popular antenna due to its small size - it's a 5-band HF aerial, under 8ft square, and is ideal for the small QTH.  One of the issues for home-constructors has been how to cut+tune the folded-dipole elements.  Fortunately, G3TXQ came up with the idea of using single dipole wires and feeding the aerial via a 1:4 balun which transforms the 12.5-ohm aerial back to 50-ohms to match your transceiver.

Choose from our standard Balun or opt for the QRO version with increased power-handling.  Larger ferrites allow for higher power and are ideal for users who are fortunate enough to have more than the 400w limit we have here in the UK!

There are plenty of articles online about this balun and how it's built - but construction is not for everyone and it's certainly not a beginner's project so we've done the hard work for you.  This is a no-solder product and ready for mounting onto your CobWeb metalwork and spreaders.  The rugged box houses a 1:4 balun for use with the G3TXQ CobWeb design (the original, by G3TPW is known as the CobWebb) and is available in 2 version depending upon your power requirements.

• Standard: 2x FT140-61 and RG-316, approx 250-watt
• QRO: 2x FT240 and RG-316, approx 800-watt
• 2x 1" Stauff clamps for boom mounting
• 2x M4 screw-terminals (plus 2 sets of washers and lock-nuts) for wires
• Overall dimensions: 130(d)x90(w)x120(h)mm
• Overall weight: 660g (standard), 775g (QRO) - box is filled with potting compound for weather-proofing
• Fitting and tuning instructions supplied (once purchased, you can also access a PDF version from your Orders page)

This is not a complete aerial - You will need to add a mounting arrangement, fibreglass spreaders and 5 sets of dipole wires (we use CPC CB19907 on ours).  For the centre-fixing kit G4ZTR Aerial-Parts metalwork which includes a 1" boom that our balun slides onto, 22mm fibreglass spreaders from All Propped Up or Engineered Composites forms a complete 20m-10m HF aerial solution that can be assembled with a just a spanner, a pair of wire-cutters and an SWR meter or antenna analyzer.  You can read details of G4ZTR's own CobWebb build here.