I've successfully used this type product for winding a loading coil on a 4" diameter form.  You can search for similar size and lengths of soft aluminum wire or tubing.  Small tubing (0.25") may provide both the workability you want while providing lower resistance (compared to #12 Al wire), plus no worries on dissimilar metal connections.  Some solid copper wire, like those 25' rolls of 'grounding wire' that are sold by Lowes and HomeDepot (anywhere from #4 up to #10) are often hard to work with, especially when trying to wind a uniform coil while maintaining coil spacing.

http://www.etsy.com/listing/115278048/6-ga-aluminum-wire-5-ft-coil-soft-pure?ref=similar_items_sash

GL, 73, Rich, K3VAT

My choice same as above.  PT0S crew was really heroic!  73, Rich, K3VAT

I agree with K2DC on this - don't see any real evidence that you'll gain anything over what you already have.
You might consider enhancing the 6BTV by increasing the number/length of radials (your minimum should be around 30) and/or raising the height of the OCFD.  Didn't notice what your operating goals are: working the 'locals', occasional DX'ing, or perhaps all-out DX'ing; working into a specific region; etc.

GL, 73, Rich, K3VAT

Most likely. You're planning to place the proposed vee right in the center of the near-field with each leg of the vee a harmonic of the vertical.  When using the vertical, you'll have max voltage at the top of the vertical, right where the vee attaches.  They will interact - how much depends on a number of factors, but like K2DC correctly pointed out "... you'll never know ... until you try it ..."  AND "... unless you intend to drop the vee while using the vertical."

The same principle holds for guying towers.  You break up (or cut to specific lengths) each guy wire by using insulators to prevent the guys from interacting with the antenna's signal.

GL, 73, Rich, K3VAT

Ah, a vertical dipole - nice construction.  You seem to have identified all the necessary components (loading coil and cap hat, one for each side; and shunt coil at the feedpoint.  Thanks for sharing.  73, Rich, K3VAT

So how short is the 'short dipole'.  Do you intend to use wire, simply hung between two high supports or something more sophisticated such as using Al tubing and/or making it rotatable?  End loading with capacitive hats are a very viable option as the losses experienced as opposed to a loading coil, are less.  Plus, the feed point Z is often higher, facilitating easier Z matching.  GL, Rich, K3VAT
 

Possibly, W8JI measured coil Q of a number of various coils including a #12 miniductor (close to 2mm wire) and found that the peak Q between 300 and 500 and the Q at 80% resonant frequency between 200 and 400.  The page:
http://w8ji.com/loading_inductors.htm contains other valuable notes that one needs to be fully familiar with to properly design loading coils.  If you haven't checked it out, it is a must read for coil builders.  Let us know how your project is going?  GL, 73, Rich, K3VAT

Have them on 40M & 20M; CW & Phone - Thank you ZH. The path was/is almost true east from here but it is a pretty long haul.  With ubiquitious worldwide spotting now available for tens of thousands of DX'ers and would-be-DX'ers, I suspect that one will see some of the largest pileups ever. GL to all.  K3VAT

Pete,

It actually depends what bands that you are most interested in and what are your operating goals (i.e., working the 'locals'; working on your WAS; all-out DX'ing).  You can optimize your OCF antenna for your favorite band and desired operating goals.

Generally elevating the feedpoint of an OCF antenna is marginally better than the center, but this is dependent on other inter-related factors such as height of the ends and the band of interest.

The roof's metal edge will definitely have an affect - how much depends on the power that you're running and the distance between the antenna and the roof (the more distance=the better).  SWR 'variations' can be mitigated, but the radiation pattern always, at least to some degree, be modified (how much depends on a number of inter-related factors that are hard to predict).

Try your set-up and see what your readings are AND see how it performs.

GL, 73, Rich, K3VAT

Thanks for the additional info.  Yes, this will work and the coil size/turns sounds feasible.  Regarding the ground system: if you could manage a few more above-ground radials and tune them properly, then I think that your performance would significantly increase.  While a choke-balun isn't a 100% necessity, they do prevent common-mode currents and in a setup like yours where you have a 'marginal' radial field, it may be a good idea to install one of these at the feed point.  The radial field is the 2nd half of your antenna and one needs to optimize it also.  See the website of N6LF http://www.antennasbyn6lf.com/ to get an idea of how to optimize your elevated radial 40M vertical (you'll need to scroll around as the links aren't necessarily handy).

GL, 73, Rich, K3VAT

I agree with N4JTE on this one: "N6LF and ON4UN have done extensive studies on a variation of your question.
Lot of factors effect vertical antennas.  BUT one raised radial is gonna be a disappointment if you expect some directionalty, not to mention the matching impedance at that feedpoint, two is minimum for raised radials in my experiments."

N6LF specifically has mentioned the need for at least 4 or better yet 8 elevated radials to get 'decent performance'.  See his website: http://www.antennasbyn6lf.com/ you'll have to scroll around to find the articles (they exist in several places).  The amount of 'return current' captured by one elevated radial is only a minimum amount, perhaps less than 10%. As Bob inferred, there are lots of other factors to consider such as near and far field ground condx; proximity to nearby objects, and height of elevated radial system above ground.

GL, 73, Rich, K3VAT

It's always good to build your own antennas.

A lot depends on the 2nd half of your antenna: the radial system.  I didn't see it described so without know a little bit about the ground radial system, it is hard to accurately answer the question.  That notwithstanding, a few turns of base coil can certainly change the antenna's resonant frequency the amount that you are describing.
GL, 73, Rich, K3VAT

At the current K3VAT all trap dipoles (one WARC at 30' and one non-WARC at 40') and one 55' tree vertical (wire running up the side of the tree and 30 short radials for low bands).  Have earned DXCC on the WARC bands with this arrangement and added a few dozen band-fills to my non-WARC 6BDXCC.

Reason why no beams/towers = relocated to retirement community with HOA limitations against towers and visible antennas such as yagis/quads/hexbeams/etc.

Plans: none.  Perhaps build more efficient dipoles (fatter, rotatable and higher in the trees), but am content with current arrangement.

73, Rich, K3VAT

Yes, you can place the ends on any convenient attachment, but try and keep several feet between the antenna's end insulator and the building (the ends of the often are the area of highest voltage).


No, it may be configured with one or more 'bends' and still perform adequately.  W1JKA mentioned "... ~ 30 degrees from straight ...", this should be 'acceptable', but I wouldn't go much beyond this if possible.  You can even 'zig-zag' the antenna to get the antenna in to fit your physical typology.

Note: as you stated that the antenna height (center) will be "36 feet" don't expect stellar performance on the lower bands.  30M and up (10, 12, 15, 17, and 20) should yield you decent DX contacts across to nearby continents, but for 40M and certainly for 80M  the vast amount of your radiation will be straight up even though there is a bit of a vertical component due to the Windom's 22' vertical radiator.  The best success for the lower bands (40M and 80M) with these Windoms is when you can manage the get both the center and the ends up to heights > 65 feet; although some users have reported remarkable DX contacts (such as working deep into SE Asia) with heights the same as you are using.

GL, 73, Rich K3VAT

No Chris, no problem here (actually the question is a bit miss-worded, but folks seems to understand what you mean).

The flag pole serves a dual function: flying the Stars-and-Stripes and as a vertical antenna.  K3VAT