DX Commander User guides

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Important Build Notes (June 2018)

There are generally THREE issues that builders might come up against when building the DX Commander ABV system.

Please remember, that this whole system is an experimental bit of fun. You can get it right and laugh in the face of $1,000 antennas whilst maintaining pureness in terms of tuned quarter-wave elements (5/8th in the case of 15m band). Please have some empathy for the crazyness of this project. Many (MANY!) people have an absolute ball with this system and understand that it it what it is, a fibreglass pole, some cut plates and a few nuts and bolts. But antennas don’t need to be expensive. To make this a true production piece of hardened complete solution will cost just as much as a SteppIR’s (BigIR Mark IV Vertical 40m-6m). Instead, this is cheap and cheerful – but with the same performance. Instead of a single element that varies in length, we nest each element like a fan-dipole.

So, you can save yourself nearly $1,200

1. The guy plate may not sit perfectly on the lower part of the second section (just above the top section) due to very tight tolerances that I like to work to. It’s possible, your pole may be a whisker “fatter” then spec. In the main, I try and do a 100% inspection but once in a while, one falls through the net. You can either use a file or a piece of sandpaper to take a very small amount of material off the inside diameter of the hole of the guy plate, or just a random file. I use a small Dremmel with a sandpaper attachment. Once or twice around the inside diameter, and it’ll fit snugly. If you have issues, let me know and I can send you another one.

2. I’m in two minds whether to supply SO239s with extra-long or extra-short pigtails. I personally like the very small pigtail and if that’s the case, I suggest you connect it to the UNDERSIDE of the driven plate, don’t try and pull it over the top. In the main, I think I will supply longer flying leads and you’ll be able to take your pick. As an aside, a longer pigtail means very slightly shorter elements. Maybe that’s a better solution anyway. I’ll keep you posted.

3. The pole won’t extend quite long enough to allow a decent amount of tolerance between the top of the 20m element and the upper spreader. Using a spare hose clamp (supplied), use that to move the upper spreader up the pole 10-15cms (4 to 6 inches) and you’ll have lots of room to play with.

4. Unraveling the bunch of D10 wire. Find the end of the wire and remove the insulation tape. Ask your partner (or closest tree) to hold the end of the D10 and walk away, turning the D10 like a wheel away from you. Basically, just unwind it. D10 is EXTREMELY tough wire that is double-sheathed and has three tinned copper and four tinned steel wires. Because of this, it has some “memory”. but once it’s unwound, you can deal with it. To split the pair of wires, connect a battery drill and unwind from one end. Be careful though because you are now inducing another spin into each wire, so when you feel you have done enough, don’t just drop the now unraveled D10 to the floor. Instead, grasp each one and hold them apart whilst they “unspin” in your hands. You’ll get it :)

5. My Vertical caught fire! Well mine didn’t but my customer tried 1000 Watts on FT8 on 20m band. The very top of his custom wire element started to melt, caught fire and the rest is history. Solution, check your elements can handle the power before turning up the wigglies :) D10 appears to be very difficult to set fire to…

6. The length of the pigtail between the SO239 and the Fork Connector will make a small difference to the tune. Recently, I shipped a batch of small pigtails (see note 2. above). Discussing this with a customer, we have realised that if your whole antenna system is out by say 200 KHz, you can simply make this pigtail longer. A simple hack if you intend to work CW or Digital (say).

UPDATE for 2018 Spec

Guy plate: This is now manufactured in 8mm BLACK PE4 plate (up from 6mm) which is extremely substantial. Holes are the right size to fit elements with loops through easily and the guy points will allow 6mm carabiners to be connected with room to spare. Alternatively, just tie your guys to this point. I like carabiners because I can easily disconnect and lay antenna down and erect speedily. Having a 33% increase in plate thickness means much less bend.

Upper Spreader: I was never quite comfortable with the 3mm thick upper spreader. It had too much bend and didn’t look quite right. I have now specified this at 5mm and it is much more substantial. I’m delighted with the result.

double-eye

Upper Double-Eye

Upper Double-Eye: NEW. Again, 5mm nylon BLACK plate and is a very snug fit at the 7m point. I was never totally comfortable with the “Heath Robinson” arrangement for 30m and the way that 40m was fixed up the tube. This component solves the problem (and now in BLACK).

Miniature Carabiners: I am now shipping 2-packs of black plastic carabiners (gives you some spares). These are for making up the extensions for paracord (and shock-cord), connecting your elements to the upper spreaders. The holes on both upper spreaders are correctly sized to fir the carabiners.

Finally, don’t over-tension everything. Your shock-cord should still have a little ”give” left else you may over-stress the fork connectors.

D10 Complimentary Wire: I ship just over 100m of wire with all All-Band-Vertical orders. This is cheap-and-cheerful wire. Feel free to use your own. A reel of very nice flexible wire is just a few dollars (pounds) on eBay (for instance). In testing, D10 will happily accept 400W key-down, full duty cycle RF for HF. I do not have a licence to test this any higher and in light of the recent customer experience where his antenna caught fire using an unknown wire, please increase your power gradually to test. Certainly, 1,500 W SSB will not be a problem but 100% duty cycles (RTTY / FT8) is extremely hard wearing on all your equipment. Even CW is not 100% duty.

Permanent fixing: Many have done it successfully. Use some self amalgamating tape maybe and epoxy glue between the sections. I made a film about this here: https://youtu.be/ZamtSHzzVWQ. I have been informed by James that the glue “cracked” so you may want a different adhesive.

(Note for importers: Export trade tariff code from UK is 85176930).

* USA Import tax: None for under $800 :)

Watch 3-part series of M0MCX building the DX Commander All-Band-Vertical for special-order

How to do a Fast Deployment of your DX Commander Antenna

Build Tips and Tricks

Using Hose Clamps to protect your investment

How to dismantle your DX Commander