This project started in December 2002 when I built the 2m Dip-Yag antenna. Will post further detail and building instructions of the Dip-Yag in a future.
The Dip-Yag antenna worked exceptionally well but is was only a 2m antenna and I was looking to use a dual band antenna. I ran into the DK7ZB Duoband-Dipole for 2m/70cm and decided to use the 2m and 70cm design from DK7ZB except that I choose a gamma-match instead of the DK7ZB matching unit. The gamma match served me well through the years and does have its pro's and cons. One thing that I like is the fact that you do not need a watertight case to house the matching unit one of the reasons for using the gamma.
I had all the aluminum and parts readily available and the construction was done when I had the time. Here is an images of the material I used.
Bill of materials:
1. 1 x 1.5m (16mm OD) Aluminum pipe
2. 1 x 535mm (25 x 25 mm OD) Aluminum square tubing
3. 1 x 150mm Coax Centre and Dielectric
4. 1 x 200mm Gamma Rod (10mm) length
5. 1 x SO239 Aluminum bracket ( 25W x 35L x 45 H mm) hole 15mm.
6. 1 x SO239 Socket (Four hole type)
7. 2 x 10mm flat aluminum to construct the matching clamp (See images)
8. 8 x 19mm Stainless Steel selftapping screws
9. 1 x 23mm Stainless Steel Bolt + lock nut
10. 1 x 28mm Stainless Steel Bolt + lock nut
11. 2 x TV U clamps to fit installation pipe
12. 1 x 12mm x 15mm x 8mm Aluminum plate
13. 1 x 70mm x 100mm Nylotron (white cutting board)
14. 1 x 30mm x 60mm Nylotron (white cutting board)
15. 2 x 35mm Stainless Steel Bolts + lock nuts
16. 4 x 13mm ID plastic end caps
17. 2 x 21mm ID plastic end caps
18. 1 x 10mm OD rubber end cap
19. Marine Sealer Silicone
20. Self vulcanizing electrical tape
I am not going to go into great detail here as there are more than enough info here and also in the links.
UPDATE: The 2m side of things works great but 70cm is not so "hot". Now you can add another 70cm element that should give a better performance. I would suggest another element if your intention is to work 50 km plus on 70cm. This is a cheap and great antenna for beginners in amateur radio if you want some directionality.
