After months of mucking about and testing, I FINALLY pushed the new site out last week.. Only 3 bugs found so far; 1) Netherlands didn’t have any shipping options and 2) USA between 12kg and 20kg couldn’t get a shipping quote! All fixed now and it seems to be working.
Right now, we’re sorting this old site out and upgrading to latest versions of PHP etc.. The main shop is now over at dxcommander.com
All you need is the target frequency and velocity factor for this one. However, if using economy coax, your quoted VC may be off, so if that’s the case, you may want to measure a 90 degree test piece (that’s also shown in the calculations).
To check for accuracy, you can cut a 90 degree section of coax and short out the end. Attach to your analyser and you should get zero SWR at the target frequency. Just a tip.
Here Is the Excel Spreadsheet: phasing harness calcs
I have custom boxes made that keep my shipping cost effective, staying under 1.2m in total length.
Kits are shipped in the oblong boxes and single poles in corrugated cardboard.
I notice that CamDesk is offline. This is my download which I originally deleted – but since I have discovered that CamDesk is offline, I managed to find it in my recycle bin for others to use.
This is a ZIP file. Obviously take necessary precautions when unzipping etc. I’ve had this installed for about 2-months.
NOTE: It’s a self executing program file. It doesn’t need DLLs and doesn’t “install” itself in Windows. It just runs from the install directory and you can move it around, say on a USB stick if you like.
Some people aren’t quite sure how easy it is to tune a mono-band quarter wave. They are cheap and extremely easy to build.
Here’s how:
An inverted L is just like a vertical apart from the fact that instead of going straight up (like a tuned quarter-wave), it turns 90 degrees somewhere.
You might like this one:
All antenna love a bit of height.
Here’s a fun video:
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
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!
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.
* Thank you to Aubrey (AubsUK on YouTube) for the Online version below:
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. Continue reading
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.
I’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.
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.
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.
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/
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 Rudy Severns, N6LF did in a controlled scientifically based experiment.
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!
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
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. Continue reading
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
One of my aerials has just come down in the wind, a 40m compact dipole arranged as an inverted V with the ends coming down as far as the 6 feet fence height.
My garden is about 15m wide (actually it’s 51 feet wide, so a whisker over) however it’s too small to fit in full-sized flat-top dipole but an inverted V works well. Whilst you are at it, why not add in elements for 30m and 20m and have three bands on one feeder?
Width of this antenna is 15m. You can make it smaller to suit.
I have designed this antenna to be a flat top with droopy legs. The centre will be held up with a very sturdy aluminium scaffold pole with a 4.6m sailboard mast sleeved over the top. The aluminium mast will cross-bolt to an already installed steel scaffold bar already concreted in the ground. Bottom line is that I should achieve around 10m in height (30 feet or so).
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 with the ITU World Radiocommunication Conference(s). Many countries are now “on air” and can be heard. Be careful though, their frequencies may be different to ours.
In the UK, this boils down to 100 Watts maximum transmitter power and 200 Watts effective radiated power (* see note). Only Advanced licence holders are allowed on 60M band. You used to obtain a NOV however I believe that’s finished now.
To get around remembering everything, it’s probably best just to set up some memories in your HF set. I don’t know about you, but all these fancy rigs come with memories – and we never use them. Well, I didn’t up until now. 60m is ideal for getting up to speed with these Memories (and you can scan the channels too which is something else few of us know how to work!).
The following table should be able to set you up for your HF set memories (as at February 2017).
Frequencies: Upper Side Band (USB)
5.298.50So I’ve been fooling around on 60m band lately on SSB as well as CW and digital modes.Today I decided to see if using AM might strike it lucky for me.
AM is a mode I remember from my youth. All the original imported CB sets were AM at that time and I seem to recall that I enjoyed the sound quality. Somehow it’s more relaxing than FM. Maybe its because you don’t need squelch, I really don’t know. FM has great clarify but AM just has a roundness to it.
TS990s on AM
Most modern radio sets come with the ability to transmit on AM but there’s an element of setting up, for instance with an old fashioned AM CB radio, you probably don’t set up the carrier and then adjust the microphone gain to achieve the modulation.The good news is that out the box, my TS990s seemed to transmit AM pretty well. I have an additional benefit in that the AM carrier on the TS990s is 50 watts, with voice peaks naturally falling at around 100 watts, perfect for maximum juice on the 60m band which limits our power to 100 watts anyway.
[EDIT] This is a very old post from about 2018..
The shop is on the link to the right, else the VERY OLD article is below:
I finally found some time this year to pull all the components together to test out in a real-world setting, the idea of using multiple elements on a single vertical fibreglass pole to achieve very good SWR and radiation patterns.
The problem with verticals is than in the main, people need either ATUs or they use that awful UNUN business with a single radial. The 9:1 UNUN business is just inefficient and the only way to to use an ATU effectively is at the feedpoint, not at the rig-end due to the severe losses.
A feedpoint ATU is expensive and generally requires a 12V power source. And long verticals have awful radiation patterns beyond 5/8th of a wavelength.
So the only way to reliably install a vertical and dispense with any worries about SWR and power handling is to build a mono-bander.
Regulars will know that I’ve been playing with the idea of adding separate elements to a 40m vertical mono-bander to add in the odd frequency, say 20m – but the interaction between elements can cause impedance issues (read SWR).
With development, I’ve discovered the optimum spacing between elements to achieve pure quarter-waves on 40m, 30m, 20m, 17m and 12m. It happens that the 40m vertical will resonate on 15m for excellent very-low radiation patterns and with the addition of a shorter-then-normal 10m element (around 2.6m in length) one can get radiation with a regular quarter-wave pattern, although the idea of using a ground-mounted vertical for 10m is slightly off-putting. There are other methods to get good radiation on the 10m band.
A picture speaks a thousand words, so, without further waffling, here is the prototype in action. It uses a regular DX Commander fibreglass pole which is around 9.7m in length with stainless hose-clamps using 8mm ID aquarium tubing (softened in hot water to push over the clamps). These clamps don’t scratch the tubing and securely hold each section from slipping down in a gale.
The base plate (radial plate) in the prototype is an aluminium angle with an SO239 fitted. The centre conductor is soldered with added heat-shrink and flooded with hot-glue. Connectors are used to connect to what I’m calling the “driven” plate with stainless nuts. RF enters the driven plate and self-selects the band it wants, just as a fan-dipole would. A guying point made from Nylon 66 keeps the elements optimally spaced as well as securely hold the mast upright at 1.2m off the ground to three guy stakes.
At the 5m point, a “spreader” plate houses the 20m and 17m elements on 3mm bungee cord with the 30m and 40m elements passing straight through. At the time I took the pictures, I had dispensed with the 15m and 12m elements.
In operation, I achieved better than 1:1.5 SWR across the operational bands selected. It was fun leaving WSPR mode running and allowing it to change bands without any ATU etc.
This antenna will comfortably handle 5000 Watts, although of course, the author only ran 400W RTTY for long periods for practical testing.
Hand-production of this system is extremely time-consuming so I am about to launch this with slightly lighter-weight and machined components to reduce cost. Target consumer price will be around £99. You’ll just need to add the wire and follow the instructions.
If you’d like to stay informed about progress, let me know.
I’ve just had an interesting discussion on 40m this evening with Peter, OH6GHI, also an antenna enthusiast. I happened to mention that I was listening to him on both VFOs. VFO A on my dipole and VFO B on my vertical and I found the stereo image very interesting as the polarisation of his signal to me changed.
We got talking about half-squares and I confirmed that we were talking about the same thing, basically 2 x 10m verticals separated by a 20m top section. The half square is fed in one corner and according to my MMANA model, this should present 50 ohms and a great SWR curve across the whole of 40m.
I switched on the other evening and heard a very quiet DX caller on 7.142. It was YC0LOU from Indonesia and I could only pick up parts of his call. He called and called and had no takers. In fairness, he was extremely quiet but as the sun was gradually moving around the sky, he finally became audible and it was worth giving him a shout. 400w off my inverted V at 7m height got his attention but I needed a few blasts for him to get my call right. I put him on the cluster and he had a pile up.
Now, the point is, had I had more gain, I’d have not only heard him better, but he’d have heard me quicker too.
So I could add more height to my Inverted V but the difference between 7m and 10m isn’t actually that much at 5 degrees off the horizon – not even a db. Hardly worth writing home about.
Anyway, this was the QSO that made me sit up and take stock of what I could do. I was seriously considering phased verticals for DX when I thought up the idea of having a switchable wire yagi. Either firing East or firing West.
Like me, you may already have an inverted V dipole up for 40m, all you need to is build another one about a quarterwave in front – or behind your existing dipole but out of a single wire. You don’t need to feed this with coax, it’s a parasitic element, like a 2 element yagi.
Having recently taken delivery of a Palstar AT4K manual tuner, I was keen to get her into production to replace my CG5000 in the attic.
Problem: the route to the attic from the shack is complex but I have a number of spare coax runs going that way including a couple of RG58 cables that I installed about 10 years ago as backups. Actually I originally installed three RG58 lines but I’ve been using one of them to send 12V up the line to the ATU.
After MUCH research, I finally used about 20 feet of parallel coax feeders, connecting ladder line to both ends. To clarify, I run about 12 feet of ladder line from the ATU to the parallel RG58 cables. I soldered the ladder line to the inner core of the RG58 coax and shorted the braid-to-braid. My 20 feet of RG58 runs to the attic, through walls, up ceilings etc and in reverse, I connected the ladder line to the RG58. Again, I shorted the braids of each line to each other with a solder blob. My ladder line then has another run to the feedpoint of a large 60m loop that runs through the attic and around the garden.
The results have been quite amazing. Comparing my 40m reference dipole to the the CG5000 (SG230 type) ATU feeding the 60m loop has always shown that the loop was about an S point lower than my reference dipole for most stations.
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 if you multiply the quarter wave resonance by 3.03, you’ll have the next available usable band. In this case, if you tune a 40m vertical to 7.00Mhz, you’ll have the whole of the 15m band to play with with a centre-point of 21.300Mhz. Oh, and you’ll still have the whole of 40m band under 1.3:1.
Now here’s the controversy:
Most people who read antenna publications or the ARRL handbook believe that if you actually make this antenna, you’re creating a cloud-burner on 15m.
Technically correct (sort of) – but for DX, wrong.
On the surface, the 10m long 40m vertical that’s used on 21.225MHz does indeed look like a cloud burner. Here it is. 15m band in green -vs- a pure quarter-wave in red).
(click to expand quarter-wave in red, three-quarter wavelength in green)
The A3S is 14Kg (That’s 30 pounds in US money 🙂 )
I was worried that the combined weight of a Create Rotator an aluminium pole *and* 
an A3S Cushcraft might be too much for my little lighting rig.
To test it out, I fitted the Create Rotator to the mast and added a 20Kg dumb-bell weight and started the motor.
It lifted without an issue so I’ll go ahead and plan to use the A3S for next field day.
How mad is that? !
Had a ball with CQWW this weekend putting just over 1,000 QSOs in the log. 10m was very busy. The band scope on the TS-990s radio was extremely full with hardly a gap from 28.300 to 29.000 (and some!).
A couple of times, I used Audacity (software) to record out the back of my Kenwood TS-990s and caught some interesting sound-tracks.
Mostly, I forgot to hit the record button, particularly when I hit a very fast pile-up to the US but I found time to catch the tail end of this one after it had slowed down a bit.
Here’s a “perfect” example of a CQWW “rubber stamp” contact. Continue reading
I had a case made for my ACOM 2000 made a few years ago. I’m pleased to report that it’s a great addition to the Ham Radio stock of toys and extremely handy for Field-Day operation.
This job is not for the feint-hearted. You will need a natural tendency for engineering, be accurate and be comfortable with knots. However, there’s no reason that most small teams of keen amateur radio operators can’t build this as a project for field day use.
Let me explain how I built the one shown in the pictures, then I’ll cover the learnings with you later along with my own do’s and don’ts. Continue reading
I love engineering challenges and I needed an elegant solution to mount a vertical antenna right on the corner of my house.
In the end, I used 3 x 24 inch T brackets from Barenco Antenna Hardware store. Poor Brian (Barenco owner) was a little confused by my request but he dispatched my order all the same and I’m pleased with the results.
By the way, a little tip. Don’t use those RawPlug type anchor bolts, they expand and they are tightened and could break off the side of the brick, particularly right on a corner. Instead, use Multi-Monti bolts. These cut a thread inside a pre-drilled hole. The beauty of Multi-Monti bolts is that you can remove them and re-install them at will. If you want to fill in the hole afterwards, use Frame Mastic from ScrewFix (or similar). You will never know your aerials were once there.
They used to call this the “AT&T Wiremans Join” but frankly, it’s the best way of joining wire together anyway. If you are joining insulated wire, first strip away about an inch of insulation of both ends.
If you have stranded wire, twist the strands on each wire together and solder them into a single fat strand.
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 U bolt saddle clamp.
Most radio amateur operators look at a pole* and immediately wonder how they might use it in their hobby. It becomes a weird past time and can become somewhat of a burden when passing for instance, a section of tubing in a handy-man store. I have to stop and work out if they nest together – or will they go inside some other tube I might have.
However, I have solved one riddle which is what diameter pole can I slip inside a standard steel scaffold tube?
I always fancied a low-angle vertical for 10m band and after doing my research, came across the Solarcon Imax 2000. It was a toss up between this, a Sigma 4 copy or the Sirio 827. The Sigma 4 is now called the Sirio Vector 4000 and I discounted this one because of the size of the radials which seemed excessive for my plot , Same with the Sirio Vector 4000 which is just too tall. Even so, the Sirio Imax 2000 is still 24 feet in length. But read on, it’s actually fairly stealthy for such a tall antenna.
I have used Aircell 7 now for a number of years and have finally replaced all my patch leads in the shack with precise lengths of Aircell 7 coax from SSB Electronics.
For longer runs, I’m still using Westflex and Ecoflex 15 but for portable operation, Aircell 7 is nice and bendy, easy to col up – and has pretty low loss, particularly for HF and short runs (up to 20m for VHF).
I use a lot of fibreglass poles with wires strewn up the sides, normally in a lazy helical fashion so that they don’t flap about too much.
I have great success with these poles as regular readers know however I have noticed that certainly wet weather can detune them ever so slightly. Effectively, they become slightly longer and I fathom that as the fibreglass supports become wet, I am achieving some slight inductance with the water that drips from the surface and gets between the wires and the poles. As soon as they are dry again, the tuning comes back to normal. Continue reading
Essentially, this is a single 1/4 wave vertical antenna with ground radials, complimented by a pair of parasitic verticals; a reflector and a director. It will deliver around 6db of additional gain over a standard vertical with a beamwidth of around 70 degrees. I have built mine pointing 300 degrees so that I can work the US easily at night.
I call this the M0MCX VPA (Vertical Parasitic Array).
Hours of planning and modelling with MMANA has finally produced an excellent and extremely economical method of producing gain in one direction, although the front-to-back ratio isn’t superb, it still has some rejection. Continue reading
I’m currently using DM780, parrt of the Ham Radio Deluxe suite of programs to conduct my digital hobby. Some of the modes are extremely fun – and I particularly like the very fast speed of BPSK125.
Recently, I have improved my very success rates calling CQ with this script:
5 CQ CQ de MØMCX MØMCX 4 CQ CQ de MØMCX MØMCX 3 CQ CQ de MØMCX MØMCX 2 CQ CQ de MØMCX MØMCX 1 CQ CQ de MØMCX MØMCX PSE K<stop>
I think it mst be quite a compelling trace to follow on the waterfall because once I get to zero and ask PSEK, I more often that not get a hit. It’s certainly better than the old standard :
CQ CQ de MØMCX MØMCX CQ CQ de MØMCX MØMCX PSE K<stop>
But it’s only for fun!
I used to host the last free version of HRD version 5.XXX however I had a (VERY) polite note from Dr Michael Carper (WA9PIE) explaining that the version I was hosting here, was actually compiled by the new HRD team, after they purchased /acquired the rights from Simon Brown.
Michael was at pains to explain that he wasn’t being heavy handed, he just wanted me to know that technically, I was giving away *his* product.
Silly me!
That download has now been removed – but I’d like to take this opportunity to congratulate Michael on his tone, friendliness and professionalism. In this modern fast-paced world, it’s becoming a rare trait.
But WAIT! The latest version of HRD is actually better and has amazing support too. Version 6 is awesome and has a number of enhancements including a wider selection of rigs, FSK keying etc etc.
Suggest you check the HRD guys out here – and there’s a 30 day free trial!
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 radiation. Continue reading
James (M0YOM) and I are pretty excited about a new automatic, solid state linear amplifier from the ACOM stable. 160m through 6m with continuous duty rated at 600 watts. Well, when I say portable, I mean it’s more portable than say the ACOM 2000 – but still heavier than say an AL811. But hey, it’s super sexy, automatic and has that amazing legendary ACOM metering and inbuilt protection.
I’m always curious to discover if a mono-band antenna will work efficiently (or otherwise) on another band. I recall that when I first studied antennas, it was explained that a dipole antenna will be resonant on every third harmonic. That means a dipole for 7.1 MHz should also work on the frequency three times bigger, in other words 21.3 Mhz. Actually, experience tells me that the real resonant frequency will be a little higher.
1/4 wave vertical for 40m band can also be a 5/8th for 15m band
