Signature 18m Multi-Band Antenna Nebula Kit

Description

Nebula xTreme DX Commander 18m Antenna Kit

Now with grey high-density polyethylene marine UV stable Plastic Spreaders

Building on the success of the original DX Commander designs, the giant 18m eXtreme delivers all HF bands from 80m through 6m (and 4m as it happens) in a vertical package with a price/performance curve, unrivalled by any other antenna on the market that will achieve fast and instant band-hopping.

For 2 x VFO radios, you can use this same antenna on two bands at the same time, tuned and ready. There are no control wires, no moving parts – and no circuitry to go wrong.

The eXtreme Nebula kit is shipped world-wide in two boxes, 1) the very large eXtreme 18m DXC telescopic pole and 2) the kit of parts.

18m Telescopic Pole

Weighing in at a hefty 6kg, this 12-section telescopic thick-walled pole is genuinely a monster. The base has the customary DX Commander screw cap, albeit MUCH bigger than normal. The screw threads are large enough to accept the ground plate with ease. Base of the pole is 73mm. The top of the pole has a plastic loop. You may use this to assist fitting the 80m element before a foldback (optional).

To give you an idea of this system, here’s an experimental use for the 18m DX Commander used during CQWW 2022.

Conversion kit

The box of components includes the following:

(Quality Components: See this page)

• The DX Commander Ground Plate in 3mm thick laser cut 5251 alloy, with the hole for SO239 assembly (supplied) and 15 holes, pre-tapped for ground radials. Use up to 4 radial wires per fork connector and you can double up on fork connectors to deliver a mind blowing 120 radials.
• The Driven Plate, again in 3mm 5251 alloy, laser cut with holes spacings to allow a selection of elements, as required. Choose 2 elements for say 80m and 60m. Perhaps a low-band special, say 80m, 60m and 40m. Perhaps an equidistant 4-hole pattern in-built into the template for folks who only want to run 4-elements, perhaps 80m, 40m, 30m and 20m. And finally, for those brave enough, run all six elements to give you the whole orchestra from 80m through to 6m.
• The kit comes with five x 10mm thick plastic plates. The 4 lower plates are a massive 180mm in diameter. Each of the plates have different hole patterns to fit snugly on the pole at just the right point. All the plates can be used as guying points should the user want to protect their investment from even the stormiest of weather. The fifth plate, near the top is 75mm in diameter and allows for a connection point for the 80m fold-over as well as the 60m spreader or 20m as a 5/8 element.
• 3 x 100m DX10 Wire (elements and radials)
• 100m 2mm Mastrant guying cable is also included in the kit to allow builders to guy their antenna at three heights with a radius of 5m – 7m depending on area available. Guy stakes need to be sourced locally.
• The stay up kit is delivered in the form of the hex HCL EzyClamps
• 22 stainless nuts, washers and wing nuts together with a large selection of fork connectors are also included. These are the same as used on the DXC Classic along with lengths of double-walled, glue-lined marine heat shrink to protect element ends, fork connectors and the various mechanical loops to keep your elements taut.
• Further, we are including a long length of Marlow (Dyneemaa) marine shock-cord.

BANDS

The advantage of the eXtreme Nebula over the standard Classic or 12.5 Signature is that your 80m element is fully vertical and top loaded via a small linear loaded section for fine tuning giving you better night-time DX capability. Further, you also have the option of running 60m as a quarter wave too or a 20m element as a 3/4.

It should be noted that depending on how the linear loading is arranged, you can achieve a perfect tune on the 11m and the 10m bands too (as a 1 and ¾ wave). There is extremely useful gain on these bands, achieving 6dB better DX gain (5 to 10 degrees above horizon) over a quarter wave.

SHORTWAVE LISTENING

Because the antenna is almost resonant regardless of where you tune, the eXtreme Nebula is a fabulous shortwave antenna, achieving amazing listening results with broadcast, weather fax, RTTY etc across the spectrum.

NOTE: To achieve full extension of the pole, you will most likely require the help of an additional person to grasp and twist each section with you to achieve maximum height overall. It will require a strong twist and pull. This is a heavy system with thick-walled fiberglass. It is not necessary to achieve “full” height anyway. The only element the full height assists with is the 80m band and we tune 80m by folding the element back on itself anyway.

FAQ

1. What is the gain improvement with the Nebula?

Improvement is on 80m, being almost full-sized – and the addition of 60m.

2. Why would one purchase the Nebula over the Multi-band 80m-6m HF Antenna or Signature 12.4?

Clean (not inverted L like the Classic or loaded like the 12.4 Signature). Strong. Adds 60m.

3. Would the Nebula support 160m as an inverted L or with a loading coil at the base?

It would support 160m with very light-weight wire at around the 15m point, assuming that point was guyed too. Loading coils would destroy the other bands (experience)

4. Does the Nebula require two people to lower it to the ground?

Go slow and be careful. Safety is very important. DX Commander has experience of raising and lowering many masts. If in doubt, have a watcher to see what is happening behind you. As it comes down, there can be a lot of guy wire dropping around and you don’t want people tripping up.

5. Is there a video we can view showing the raising/lowering of the Nebula?

See above video for idea of scale.

6. Which antenna would be better in high winds and heavy snow?

All of them. It so happens the original Classic has a reputation for holding up very well however like all these things, if you really do have a storm brewing, best to lower it. Interestingly, there’s one Classic that spent all winter under 6-feet of snow and it worked the whole time and came out the other side! The Signature series poles 9, 12.4 and 18m poles) are MUCH heavier than the Classic range. Most poles are known to have survived 80mph winds. Depends on gusts and a number of other factors.

DISCLAIMER: This kit is probably NOT suitable for a first-time kit-builder. Your appreciation of the scale and size needs to be fully understood. I advise strongly that you make a risk assesment before you start the build by calculating where on your land this will sit – and further that in case of any accident, it will not damage property or cause injury to bystanders or users alike.

NOTE: Tested at 1,600W key-down for 65 seconds on 14MHz. Last 3 pages of user guide for fool-proofing QRO ability.

DELIVERY: Worldwide

Note: We don’t supply those little plastic carabiners for the shock-cord ends any more. They become brittle and break. We moved to a superier solution of stopper knots and loops. See User Guide.