M0MCX – DX Commander Amateur Radio Antennas

Telescopic Antenna MastBuy 10m Pole £44.00

40m verticalDX Commander: The best heavy-duty fibreglass telescopic antenna mast supports with many happy customers.

DX CommanderUser Guides & Manuals

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How to assemble, build and maintain vertical multi-band antennas with Telescopic Poles.

 

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MOST READ POSTS . . .
Obligatory evening shot of a three element 40m array

DX Commander 40m 3 element vertical array £299

Hours of planning, modelling and experimentation both in software with MMANA and also real-world testing has finally produced an excellent and extremely economical method of producing excellent DX gain in one direction with reasonable front-to-back ratio with fast set-up time and potential for /P operations for the heavy duty operator. (Scroll down to ...

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Antenna Tow Ball Mount

IMPORTANT NOTE: This is an experimental tow-ball mount. Under test, I achieved some extreme loading however I can take no responsibility for anything going wrong. Playing with portable antennas inevitable leads to the odd "accident". So please do your own risk-assessment by calculating what would happen in any failure and that you have considered the ...

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DX Commander Bare Bones Complete 10m Multi-Band HF Vertical

SEE LATEST DX Commander ABV Release Notes 2017 I listened! Some of you wanted an economical bare-bones system without all the little "bits". Here it is! This is the listing for the "Bare-Bones" system which includes the pole and the 4 water-jet cut plates only. For me, this was the difficult part ...

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DX Commander all-band conversion kit

This is the conversion kit consisting of the Ground Plate, the Driven Plate, a Guy Plate and an Upper Spreader (only). UPGRADE October 2017: Guy plate now upgraded to 8mm. Upper Spreader now at 5mm. This assumes you already have a DX Commander pole. Check out the film: https://youtu.be/3dULHHmyKYE The kit comes without nuts and bolts ...

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DX Commander Premium Build - HF Multi-Band Vertical System

This listing is for the Premium version of the DX Commander vertical. Ideally suited to Christmas Presents, Birthday Presents and for those people who need a "plug-and-play" approach to their operating. This is EXACTLY the same kit as the 80m / ALE product I also list at the same price. Over time, ...

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M0MCX Banana Antenna - an end-fed choke sleeve resonant feedline T2LT antenna design

A new document fully documenting the design of the Banana Antenna has now been released entitled, "Banana, a Half Wave End-Fed Choked Coax Antenna". Antenna can be known as - and is similar to: Sleeve Dipole / Flowerpot Antenna The Sleeve dipole has traditionally been used by VHF antenna designers by sliding an ...

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JT65 UK Band Plan and how to stay within

The 5 MHz band is pretty cool and I've written about it before however out the box, JT65 allows you to very easily transmit out of band on 60m band. The segment we're interested in the UK is the freq block between 5.354 and 5.358. This has taken me a little ...

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Introduction to the 60m Band Plan (5 MHz)

60m is an interesting band. it's partly channelised into small segments and the propagation is a cross-breed of 40m and 80m.The band was first introduced apparently in 2002. Over the years, various countries have allowed their amateurs radio operators to use the band. All this is negotiated and approved in conjunction ...

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Obligatory evening shot of a three element 40m array

10m Telescopic Flag Pole Antenna Support DX Commander

DX Commander Antennas: These are the best selling heavy duty telescopic antenna support on the market. With over 500 sold and 100% track record, I know what I’m doing – and I use these myself in real-world RF applications. Club members, personal friends and other regular amateurs love the quality and ...

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Working 15m band on a 40m vertical antenna

Note: This article discusses the merits of a 3/4 (three quarter wave) vertical -vs- a 1/4 (quarter wave) antenna. You can build a 40m vertical quarter wave antenna and ground mount it with 16 x 4m radials and operate it at the third harmonic; 21MHz. Actually, all my experimentation has shown that ...

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Converting a 40m vertical to run on 80m / 75m band

Recently, I created a slightly loaded 40m vertical with 25 ground radials. It seems to work very well although the receive noise is pretty lousy compared to my loops and dipoles, however on transmit, it does seem to work as planned; a typical 1/4 wave pattern that outperforms regular dipoles at low angles of ...

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Raising Steel Antenna Mast on T&K brackets with pulley

I'm gradually swapping out any aluminium antenna poles for steel. Clearly these are very heavy, particularly with an antenna on top. The trick is to use V bolts (like U clamps but in a V shape) and not to use saddle clamps because the pole will not slide easily past the ...

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How to make a stealth amateur radio wire antenna

How to make a stealth amateur radio wire antenna

Until recently, I had a) a 40m triangular loop in the back garden which I called a "micro-mega-loop" and b) a 60m loaded loop that allowed me to get on 80m. The two loops looked a bit horrendous not only because of the wire in the air, but because I ...

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Special Event Operating Procedures

This note will be particularly beneficial to those who may be required to run a special event station either on the lower bands or maybe on VHF. These tips & tricks will also help you anywhere on the band, regardless of your circumstances. Preface: There are a number of aspects that ...

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Coax Loss Comparison

I can never find the comparison charts between RG213 and Henry Westlake's Westflex W-103. At last, I'll have this logged forever now. Per 100 meters: RG213/URM67(Mil spec) Westflex 103  100 MHz                      7 dB 3.2 dB  144 MHz                    8.5 dB 4.5 dB  200 MHz                     10 dB 5.4 dB  300 MHz                     13 dB 6.2 dB  432 MHz                     15 dB 7.5 dB  1000 MHz                   27 dB 13.0 ...

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In this video, I show you why you shouldn’t worry about height for your wire dipoles and loops.

Unless you can achieve leaps of a quarter-wave in size, just go with the flow (or put up a DX Commander All-Band-Vertical! :)

All contests have some sort of report, mostly the signal report then additional pieces of information, from your age to your shoe size (seriously).

Here’s me on 15m during IOTA 2017:

(100 Watts, recorded straight out the TS590SG into Audacity)

Antenna: DX Commander Vertical 80m-10m

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q-wave-vs-5-8th-wave

Compare Red 5/8th -vs- Blue W/wave

Anyone who has mucked about with verticals will no doubt have worked out that a full-sized quarter-wave for the 40m band, more or less tunes up for 15m band.

It wasn’t until my entry in IOTA Contest this year that I convinced myself that they are not a cloudburner (as many people suggest) but compare favorably with a quarter-wave, even producing more gain by 2 dB at 10 degrees above the horizon.

OK, so 2 dB isn’t a huge gain, but hey – it’s free. Take it when you can!

Don’t forget, you can do the same for 10m band too by making an element 6.83m long and folding it back a further 1.11m (for 28.5 MHz). So you’ll need nearly 8m of wire. Don’t forget, that’s insulated wire!

I’ve recently “made” a 4-element Yagi in software for my YouTube channel which should give a great match to 50 ohms.

If you’re into MMANA software modeling, here’s the file:

NOTE: This is a ZIP file because my Content Management System doesn’t like files ending in MMA. By all means have your Virus Scanner check this Zip file. There is only one file inside this ZIP. Just the MMANA file.

Quick-SWR-calculator

Here’s a really simple way of double checking how to much to trim your antenna elements.

You only need to type in the numbers in the Cyan boxes.

Just type in where it is resonant right now – then type in where you would like it to be resonant and the spreadsheet will auto-calculate the trimming.

Film: How to use the SWR Adjustment calculator.

tokyo hi power

So I have just taken delivery of a very gently used Tokyo Hy-Power HF linear amplifier.

The previous owner (retired communications and instrumentation technician for a large, multi-national organisation) replaced both fans with ultra low noise “Arctic” fluid bearing units. These are installed in 2 speed via voltage regulation manner: Low speed during stand-by (RX) and High speed during TX. (read more…)

Inverted L multi-band

Regulars will know about the DX Commanders very cool results which are now filtering through in real world successful contest scenarios.

My own issue is that I needed just one antenna that would deliver an all-band solution, certainly for the contest bands of 40m, 20m, 15m and 10m – but I also needed 80m in the mix too.

My holiday home has a very compact small garden so the option of putting up a dipole for 80m is out the question, but modelling suggested than exchanging the 30m element for an inverted L for 80m should work.

The 80m element therefore starts vertical, like all DX Commander elements and turns a sharp corner at 6.9m above ground and droops down for around 13m or so, hanging over a bush at around 3m off the ground. Probably not perfect but perfectly adequate to score 44 QSOs inside an hour on the Saturday eve of the IOTA contest. That score includes 16 different IOTA multipliers, certainly a wide spread around Europe.

(read more…)

featuredimage-ground-plate

IOTA-graphicI’m absolutely delighted to report that I was placed 4th overall in the world for IOTA-Fixed station, Unassisted, Low Power, 12-hour section. This was from a holiday home and I installed the antenna inside 1-hour.

Results here  – but what makes this more remarkable is that I only used the one antenna from 80m through 10m; DX Commander All-Band-Vertical.

For 80m, I confirgured the DX Commander as an Inverted-L, replacing the 30m element. Of interest, 30m was still achievable (albeit with a 4:1 SWR). Although 17m is not a contest band, I did notice some slight interaction with the new 80m element, however SWR was still acceptable without an ATU.

I logged 300 QSOs however I notice after adjudication, that fell to 289. Pretty good, only dropping 11 QSOs. And I was amazed at how effective the 40m element produced such startling results on 15m, effectively as a 5/8th. Even 10m as a 2.5m long, ground mounted quarter-wave was getting in the action with short skip too.

All in all, I’m extremely delighted that I test-proved this antenna from a holiday location in competition with my peers, who were using genuine fixed-station antennas.

a

I’ve been scratching my head for years how to model an appropriate ground with my ground mounted Vertical Antenna radials.

I’d like to thank Sigi, DG9BFC for clearing this up for me.

HOW TO:

NOTE: I like to draw a small feedpoint in all my HF antenna models, like a 5cm length of wire where my “source” (coax) is connected to. Particularly useful for fan dipoles and for making other adjustments. I’ve left that part out for simplicity on this How To since I’m trying to make this super easy.

(read more…)

shipping

After much research, I’ve managed to get the price to under £30 for USA, an additional £10 for Canada with Russia and Australia incurring extra costs. I’m doing this shipping at cost folks via a tracked parcel. You can buy shipping cheaper – but with horror stories I’m afraid.

  • Still a hugely economical antenna for what you get.

PS Postage for USA is only £30 using MyHermes for delivery to OCS in UK and on to United Parcels Service for local delivery in USA.

Experience is suggesting that due to the low price, no customs or duty should be paid when it lands your end for most countries (although I can’t guarantee that – although my shipping people tell me it’s under the threshold).

Start here:

https://www.m0mcx.co.uk/store/products/dx-commander-premium-build-hf-multi-band-vertical-system/

radials

I’m often asked this question and after 5 years of development, I think I finally have the answer thanks to both real-worl experience and the work that Ruby Severns, N6LF did in a controlled scientifically based experiment.

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Read the PDF document on this link:

Raised Radials are a completely different kettle of fish. These are tuned to the frequency i question and can give varied results.

PS – Another superb read for the very clever folks is here:

Good luck!

banana-antenna-stock

A new document fully documenting the design of the Banana Antenna has now been released entitled, “Banana, a Half Wave End-Fed Choked Coax Antenna”.

banana-antenna

Banana Antenna

Antenna can be known as – and is similar to:

Sleeve Dipole / Flowerpot Antenna

The Sleeve dipole has traditionally been used by VHF antenna designers by sliding an external metal sleeve over the coax and connecting the sleeve to the braid of the coax so that the antenna appears to be centre-fed with an outboard “sleeve”. Some commercial CB antennas are also made this way. (read more…)

WARNING: This post has been replaced with the following analysis and design:

Banana Antenna Design May 2017

– – –

The Resonant Feedline Antenna is also known as:

• Sleeve Dipole (& Flowerpot Antenna)
• Resonant Feedline Dipole (J Taylor, W2OZH)
• Tuned Transmission Line Trap, T2LT (CB folks)

For more about common mode chokes, see this article:

Pictures of this experiment follow including the 10-25 MHz >8K choke follow.

Coax Transmission line coax stubs are frequency dependent. Making a stub for one frequency means it WILL NOT work for another frequency. My example is for a 20m Resonant Feedline Dipole, sometimes called a Sleeve Dipole or Resonant Coax Dipole or Tuned Choked Coax Dipole.

So you have an approx 75 ohm impedance antenna and you want to get the best match you can. Take the wavelength of the frequency, multiply it by the velocity factor of your 75 ohm matching coax and multiply again by 0.0815.

For example.

14.225 MHz = 21.089 metres
21.089 * 0.66 (what ever your velocity factor is) = 13.19
Multiply 13.91 * 0.0815 = 1.134m

Therefore, your transmission line coaxial transformer will be 1.134m long which is apparently about 29 degrees around the 360 degree circle.

Data found here: PA0FRI page.

Finally, I discovered MANY pages on eHam and QRZ forums of people asking the same question but most answers are with people answering questions which were not asked – or giving advice how to fix the antenna, or live with it. Why Americans need to argue the toss when others just need answers beggers belief :)

The 5 MHz band is pretty cool and I’ve written about it before however out the box, JT65 allows you to very easily transmit out of band on 60m band. The segment we’re interested in the UK is the freq block between 5.354 and 5.358. This has taken me a little while to get to grips with this because although the band-police are complaining – and the RSGB has also warned users, nobody is giving a clear instruction on how to achieve staying completely within the band allocated to us.

In the UK therefore, there’s a couple of simple steps to take to make sure you won’t transmit out of band.

If you don’t have JT65 already, get it here: http://jt65-hf.com/downloads/.

Run the installer and interface your rig as you would any other piece of software that connects to your computer. If you are after help with that part of the problem, there are other places to hunt solutions down, not this blog.

Go to file > Settings and click the Frequency tab at the top and edit the frequency for the 5 MHz band so it reads 5.356.

File > Settings > Frequencies

File > Settings > Frequencies

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