SKCC 5123T----- FISTS 14979----- Flying Pigs 2331----- NAQCC 3610-----QRP ARCI 14176-----Polar Bear 257

Saturday, February 18, 2012

Portable Inverted U Doublet

After locating some 20 foot crappie poles, I wanted to try a new way to use them. The idea was to mount them on the military mast poles I have. I had used the military mast off a hitch mount on the truck to support hamstick dipoles before. With two 20 foot poles that yields a 40 foot span, plenty for a full size dipole at 20 meters.

Now as for mounting the crappie poles on the mast. I found that a 1.5 inch PVC four way fitting slides nicely onto the military mast. I had to take the mast into Home Depot to find that out. Then I needed some short lengths of PVC out the sides. Well Home Depot sells 2 foot lengths. Very handy! The 20 foot crappie pole fits into the 1.5 inch PVC and the butt end won't go through. When the PVC length is put into the fitting this secures the poles into the fitting. Cheap and easy!

I thought I would try a 40 meter dipole with the ends hanging down. Well yes it can work but the ends hang down so close to the ground I needed to tie them off with a guy. line. That is fine but I could support the ends with more poles if that is the case.

The next idea was a shortened dipole on 40 and hope I could use it on 30 and 20 meters also. I setup a dipole or doublet I have that has reels to adjust the length. I just eyeballed a length that would keep the ends above head level. So 40 foot across the top and the reels hang straight down. This is the inverted U shape that W4RNL wrote about. After I took it down, one end was 27 feet and the other 25 feet. So next time I'll make them 26 and 26 for the total length of 52 feet.

And now the happy ending. I setup the HB1B and the BLT tuner. The doublet is fed with 300 ohm line. It did tune on 40, 30, 20 and 10 meters. So now to try it out. My first contact was W4FO in Tampa on 30 meters, next was K4GXY in Lakeland on 40 meters and last why not take advantage of the DX contest. So on 20 meters I worked PJ4X Bonaire, PJ2T  Coral Cliff Curacao, and then TI5W in Costa Rica. OK enough to say this one works and I will keep it in mind for future portable ops. All this was in my driveway at home. Keep in mind this one will get some looks from passer-bys.