Thursday 23 April 2020

Doublet Up and more to come

On Saturday I installed my doublet and the center hangs down to about 23' above the ground.  It's heavy over a long run so it does sag some.  I have decided to prepare my center support to take some of the load off and also to provide me with another use.  More on that later.

I tested my doublet with my tuner and found a very good match on 40, 17 and 15 and a reasonable match on 30, 12 and 10.  I could not match on 20M.  I made some contacts and was pleased with the flexibility I now have across the bands...except 20M.  I thought the issue was the length of my feedline so I trimmed 8' from it and still it behaved about the same.  Someone suggested that the length of the antenna may need some trimming.    I lowered the antenna and trimmed 2' off each end and raised it back up again.  The bands that were reasonable improved slightly in the SWR department but 20M stayed unacceptable.  Rather than fart around with this doublet to get something "reasonable" at the expense of the other bands I decided that I would prefer a tuned antenna for 20M so that I can get back to doing some QRPp work eventually.  I have decided to make a single 20M dipole and support it from the antenna support I plan to install.

In the QRP tradition I want this support to do the job with low expense and also with what I have on hand which is challenging.  I have wood.  I have a patio umbrella stand that anchors with patio stones in the NPM (non-penetrating mount) fashion since I'm not quite ready to dig and bury a 6"x6" or 4"x4" post as a base anchor point just yet.  I have a pulley and I have a 20' fiberglass Wonderpole with the tip broken off.  Originally I was going to use just the top section of this rod as I explained I was going to do in my post Still a Bit Chilly but I have changed my plan a bit to use the whole thing.  The only thing I am missing to get this support up are some hose clamps and some paracord.  I used up all the cord I had on the weekend so I will place an order at the local hardware store for a curbside pickup.

I am using two eight foot 2x2s end to end for the support and then I will strap the Wonderpole to it at the top.  This will give me close to 30' of support.  I may be able to get away with no guys at all, since the Wonderpole is light.   Just below the doublet I will attach a pulley and install a dipole for 20M.  The paracord attached to the legs will give me some added support.  Joining the 2 wood 2x2s end to end is a challenge and here is what I have come up with.


I ripped some 1x8 down to about 2" wide which is the same width as the main support pieces. the pieces are about 2' long.  I sandwich the support pieces at the joints and secured with some screws, wire and hose clamps.  The photos show wire I used but this won't be strong enough.  I don't have any fencing wire or I would use that and hose clamps are easily removed and adjusted.

I have strapped the support pole to the umbrella stand and will add the Wonderpole to it hopefully today,


More to come
Cheers de Scott ve3vvf

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