July 19, 2014
I had a Cushcraft MA160V on top of a 30′ Rohn pushup mast, but wanted to improve the efficiency – which I thought was about 60%. I am quite sure I improved the efficiency to about 80%. The antenna is 60′ tall.
I basically “morphed” an MA160V into a Sevick – W2FMI short hatted vertical – documented in his booklet “The Short Vertical Antenna and Ground Radial” book on CQ Communications Press.
I replaced the MA160V coil with a much smaller coil, and built a capacitance hat that has a circumference of 34′:
Its amazing – it took me all day to build and tune this bugger, but I ended up with 1.1:1 SWR on 1.821 mhz and 3.505 mhz.
I also increased the bandwidth of the antenna on both 160M and 80M – so that I now cover the entire CW band on both bands. The MA160V on top of the mast had about 1/2 the bandwidth as this new version.
I had an old Hustler capacitance hat hub – and so I used it with four 6′ spreaders – holding flex weave wire that is 11 by 6′ in a rectangular configuration. (Ignore the big MA160V coil in this picture – I was able to go with a much smaller and more efficient coil) – with less loss – because of the new – large – capacitance hat.
To ensure that the spreaders and capacitance hat stay “flat” (horizontal) – I used masons twine to hold the spreaders up. The Hustler hub probably could have handled the load – but I wanted to make sure, especially because its made out of cast aluminum.
The feed has a great matching circuit – which is documented on page 9-42 on the 5th Edition of the ON4UN Lowband DX-ing Book (ARRL Publication):
I now have 100 buried radials – and am VERY pleased with the latest incarnation of my 160/80M vertical antenna. Here is the very cost effective case for this waterproof matching circuit:
On The Air
The work to build this is paying off – here is what I have noticed:
- The bandwidth went from about 30 khz with the modified MA160V to 90 khz. I can now cover the CW and Phone portions of the 160M band
- The noise level has dropped by 10 “S Units” – not sure exactly what this equates to on my K3 – the implication is 60 dB (?). In any case – it is very much noticeable
- It is not nearly as susceptable to cable modem intereference as my modified MA160V was – so much so – its no longer an issue. I used to have to unplug the cable modem to make a QSO before
The real test will be when Top Band comes back in full swing, but all of the improvements very much match what ON4UN and W2FMI have written about. I worked FT5ZM on my previous MA160V modified antenna – and with these initial reports, I seemed to have improved on that “compromised” antenna – and significantly.
Only 40 more entities to go to get to DXCC on 160M and 9BDXCC!
July 14, 2014
I tried to modify the Cushcraft MA160V so it would be resonant on 160 and 40M. My idea was to replace my 40M phased array verticals with the modified MA160V’s. I was able to get it to work – but found that it just didn’t perform very well – so I kept my original 40M verticals and put the 60′ lowband vertical back up.
In my testing, I found that the 40M verticals actually load up on 160, 80, 40 and 30m, but I am sure the efficiency on 160 and 80M was not very good. On the air tests have show that the 60′ vertical on 80M was S9 +20 dB, and the 40M vertical was S9 + 15 dB – which is a difference of about 30 dB. On receive – the two antennas are very close.
On 160M, there is no comparison. Using the circuit (on the left above) to make the vertical resonant on 160M results in a difference of S8 to S9 + 15 – in favor of the 60′ vertical.
The circuit on the top right will be my attempt to use an “auto-transformer” (Unun) – to be able to multi-band the 60′ vertical to work on 160M and 80M. Right now – it does work on both bands – but I can only use my amplifier on 160M. Obviously the impedance is 50 ohms with the circuit top left – on 160M, but probably much lower when used on 80M.
The circuit in the top left comes from page 9-42 in the ON4UN Lowband DX-ing Book. The efficiency (my soil is 15 – or “average”), but with 100 radials – the resistance is pretty low.
So – my antenna lineup looks like this:
- 60′ vertical for 160/80M
- Phased vertical array for 40M – but works VERY well on 30M
- Three element, full sized 20M yagi up 45′
- N6RK Improved Feed 40′ loop (RX only on 160/80M)
The higher bands work with any of these three antennas. The 20M yagi driven element acts as a fine rotatable dipole on the higher bands, and sometimes the verticals actually are better.
Anyway, having monoband antennas on 160, 40 and 20M gives me exactly what I want and need for my DX-ing goals, which are:
- 160M DXCC – which also gives me 9BDXCC
- ATNO’s toward Honor Roll #1
I don’t care about any other awards, and have never been interested in contesting – so – I have the “dream” antenna system on a small suburban lot.
UPDATE: the circuit on the left is the clear winner, and here is how the project turned out:
It is resonant on 1.821 and 3.521 mhz. I will probably add a stepper motor so I can remotely tune the frequency.
Some day I might even change the cap hat and coil – to improve efficiency. As it is now – the efficiency of the lowband 160/80M vertical is about 60%
July 11, 2014
Here is what the sunspots look like now:
And what the Solar Progression looks like:
And what it looked like February 1, 2009:
From spaceweather.com Archives
Even with ZERO sunspots I still worked about 10 ATNO’s, and some were very rare, and some in the most difficult zones. If I remember correctly, it seemed like we had almost 3 years of zero or near zero sunspots – 2007, 2008 and 2009. It sure seemed like a dry spell – but my log says otherwise!
But looking at my log I still made steady progress toward Honor Roll – so this is why I never get too worked up about what the sunspot number is.
Having said that though – one thing I have noticed is that Cycle 24 has been really GREAT for me – mainly because 160M has still been really great, and at the same time – the higher bands have been “good enough” to work all of the higher band ATNO’s and other fun DX.
Of all the bands – 40M has become my “best friend”. It seems to have something interesting going on all day and night. Western US stations during the day, and DX at night.
But 20M is by far the money band – and so I made sure to put extra “oomph” on my 40 and 20M antennas.
Enjoy all of these spots – luckily it will be a good 3 or 4 years before we really drop down the cycle.
As they say “Make hay while the sun shines” . . .
July 6, 2014
I have three antennas for TX – RX. This is the 63′ vertical that is the Cushcraft MA160V 160M top loaded and hatted vertical – but installed on top of a Rohn 30′ push up mast. Adding the telescoping mast adds this value:
- Doubles the transmitting “surface area” – which means there is twice the area for current to flow
- Makes the antenna under the 160M top hat and loading coil “close” to an 80M quarter wave vertical
- Thus multi-banding the MA160V so it will work on 160 and 80, and where its efficiency goes from 40% on the “stock” MA160V to 60% with the “KY6R Special” for 160M and probably upwards of 90% on 80M
There are 112 buried radials, which makes a huge difference than other radial implementations that I have tried.
So that I don’t have to lower and tweak and then raise the antenna – instead of tuning the “stinger” above the coil, I just feed the vertical through a 1:1 current choke and then a Ten Tec variable capacitor – so I can tune the 160M frequency. For 80M, I feed the antenna through a 1:1 current choke. I will be re-working this feed box by adding an Array Solutions Stackmatch II switch – because it has better relays and a better circuit than the Ameritron RCS-4 that I currently have inline.
For 160M, I switch in the 500 pf capacitor and get “whatever I get” performance wise. I worked FT5ZM – which is 13K miles away, so I am “happy enough” with this configuration. By adding the switch and bypassing the 500 pf capacitor on 80M, I increase my gain by 24 dB! The capacitor is bad news on 80M. If I remotely tuned the capacitor maybe it would be fine. In fact, maybe one day I will use a vacuum variable capacitor . . . I have tried this antenna on 40 and 30M, but it is down 6 dB from a better antenna for these bands:
Here is a pair of phased top hatted verticals for 40M, and fed with the Christman method – through another Array Solutions Stackmatch II switch:
There are 44 radials on each vertical. The gain is 4 dB end fire (NE and SW) and 3 dB broadside (SE and NW).It has a measured and consistent 18 dB front to back on 40M. This antenna also serves me very well on 30M – where there is actually 6 dB gain over the tall vertical and where there is 12 dB front to back – I suspect because there is some kind of parasitic phasing effect in play on 30M. I was surprised because the spacing is 35′ – which is 1/4 wl on 40M, HOWEVER, because the hats are at 24′, the aluminum under the hats is a 1/4 wl for 30M. Maybe that’s the “happy accident” I am getting?
Finally, I use a home brewed full sized 3L 20M yagi for 20M:
And it works just fine as a rotatable dipole on 17, 15, 12 and 10M. I don’t care about these higher bands because I do not chase DXCC Challenge or band slots any more, and because this cycle will be declining to the point where the higher bands won’t matter anyway. Already 12 and 10M are just about gone. I like mono band antennas best – and wanted the best I could put up on 20 and 40 – which are the “money bands” ATNO wise for me, and also have “good” antennas on 160, 80 and 30M (I like the low bands MUCH better than the higher bands), and for anything above 20M, the yagi as a rotatable dipole is “good enough”.
I want to thank Peter, W6DEI for helping me with these antenna tests. I also ran several Reverse Beacon Network tests and found a roundtable on 80M to test with.
July 5, 2014
Radials are a lot like this skit – more cowbell:
I have 76 radials, and feel like I really need to “explore the space” by adding more cowbell (er – radials) . . .
And I just happen to have 36 more radials available (left over from taking down my 30M phased array – which only contributed negative interaction to other antennas):
Anyway, I got a fever, and the prescription is more Cowbell – er radials!
This low band season – I’m gonna be wearin’ gold diapers . . . I am sure of that!
July 4, 2014
Background and Theory
This antenna idea is based on a QST Article called “A Big Signal From a Small Lot” – April 1979 and written by N7RK, Dave Hollander. It is available on the ARRL web site for download by members. I also combine Dave’s article with pages from the ON4UN Lowband DX-ing Book, where John describes how to build the most efficient short vertical for top band with these points – and their respective pages:
Pages 9-33 through 9-48 of the latest ON4UN Book describe something that my friend Wayne, N7NG reminded me of:
” Current distribution over the length of the antenna is what defines the performance of the antenna. “
John, in the ON4UN book has a great discussion on radiation resistance, the loss in the loading devices and the area of the vertical itself all combining to determine efficiency.
Page 9-39 does a good job of giving the design guidelines:
1) Make a short vertical as physically as long as possible
2) Make use of top loading (horizontal cap hat and high Q coils) – essentially low loss. Horizontal rather than sloping down for the cap hat elements so you don’t “shroud” the vertical itself.
3) Best possible radial system (I have 76 buried, and will add another 36 tomorrow) . .
4) Keep radiation resistance high
Page 9-37 discusses the bottom loading to alter the frequency, and page 9-46 and 9-47 compare size of vertical (radiating area) and efficiency.
At 63 feet – my vertical still is only 20 meters tall – and he says the efficiency is about 60% for my soil. This means my “baby Alpha” amp – the Elecraft KPA-500 probably radiates 300 watts at best on Top Band.
With the MA160V by itself – without the help of the telescoping mast – the efficiency drops to 40 – something percent. That would mean 200 watts effectively radiated.
Some have said these values are even still a bit “optimistic” – so I usually stay away from making such claims – that always invites arguments. However – just “doing the best you can” and following the guidelines is a good pragmatic – and “best practices” approach.
Oh lastly – because my goal is to work the last 40 entities towards 160M DXCC – and check into the “Mission Trail Net” at night on 75M – I’m pretty pleased, and cannot do better on such a tiny lot.
Modifying a Cushcraft MA160V so it Approximates N7RK’s Design
Today I am going to test an idea for a lowband vertical. Right now, I have three sections from a Channel Master push up mast as a sturdy bottom of my low band vertical:
Then, I took a Cuschcraft MA160V top band short hatted and loaded vertical, and put it on top of the push up mast:
And finally, I added a 1:1 current choke and Ten Tec 500 pf transmitting air variable capacitor (so I can tune this antenna at the base – instead of tweaking the “stinger” at the top of the antenna):
This antenna is resonant on these frequencies:
- 1.821 mhz
- 5.3 mhz
- 14.010 mhz
- 21.103 mhz
And works exceptionally well on 80, 30 and 17M. I am sure it is because I have 76 buried radials, but also that I have extended the “surface area” of the vertical to be almost twice what the “stock” MA160V is – and John in his ON4UN Lowband DX-ing book describes vertical antenna efficiency. He says that top loaded and hatted is the way to go – and that the more surface area you have, the more efficient the antenna will be. By increasing the size of this vertical, I end up with an electrical quarter wavelength on 160M (only 1/8 wl on 160M mechanically), 1/4 wl on 80, and 5/8 wl on 30M. Its also almost a full wavelength on 17M – and it does work very well on all of these bands. I don’t need it on 40M – since I have a really great phased array there, and 20M – I have a 3L full sized mono band yagi that is also excellent.
Anyway – my idea for today is to adjust the sliding sections to get this antenna to be resonant on 160M and 40M – and then consider using two of these to replace my 40M phased vertical array. The thinking is that I could then take down the 63′ vertical and eliminate the last bit of “negative interaction” in my antenna farm that I have. The two verticals would work as a true 40M phased array (Christman feed), and then also act as just a single vertical (switch one or the other) for 160M. On 80, 30 and 17M, they would work using the KAT-500 antenna tuner in the shack, and basically be “too short” on 80M, 1/2 wl on 30M and 5/8 wl on 17M. If I have to – I can play with the base capacitor or even build an LC circuit to tune the antenna.
EZNec suggests that if I have 40.5′ beneath the MA160V coil that the antenna should be resonant on both 160M and 40M:
I am quite sure I can make this happen. I am sure that it will still work very well on 160, 40, 30 and 17 – where I need this to work. I do expect to lose something on 80M, but the trade off of less negative interaction might be worth doing. 80M will still be useable – but I won’t be quite so loud in the pileups. I don’t care for 80M any way . . . . but its always a hard decision to give up performance on a band . . .
An alternative idea is to increase the telescoping mast by one section – since I currently only use 3 out of the 4 sections. That would give me a vertical that would be taller than 70′ – meaning higher single vertical efficiency.
This is this summers big antenna project. I expect to gather the data this weekend – and then execute on a plan based on the data I get from my MFJ-259B antenna analyzer. EZNec is guiding me enough to try this, and the theory behind this seems sound. We shall see!
That was easy. Yes – its absolutely possible to use the MA160V on 160M and 40M. Its as easy as adjusting the stinger to tune 160M and then sliding the telescoping tubing (the Rohn or Channel Master mast) for 40M. So – I could use two MA160V’s for a killer phased 40M array and then as just two separate 160M antennas. And I could take down the tall vertical. But I decided against that.
While using the MFJ-259B, I found that if I went through the 500 pf capacitor, the resonant frequencies were:
- 1.821 mhz
- 5.3 mhz
- 14.010 mhz
- 21.103 mhz
And if I went directly to the vertical (bypassing the capacitor), the resonant frequencies fall in the 17 and 12M bands – AND – 80M tunes up much better than when going through the capacitor. Because 40 and 30M are much better covered by the 40M phased array (which exhibits about 9 dB F/B on 30M – and acting as a “sort of” parasitic array), I now have greatly improved 75/80M, 17M and added 12M. This means I have a decent antenna on 160 – 10M just in the vertical and now VERY good antennas for 160, 80, 40, 30, 20 and 17M.
So – I will keep the tall vertical up. I am currently using an Ameritron RCS-4V switch, but will probably change it to my second Stackmatch II – because its relays are much more robust than the wimpy relays in the RCS-4V. With the high voltage present on this vertical – it does require the best relays you can use.
Mission accomplished – the test was a big success, and I learned some great things and new tricks.
July 2, 2014
I only have two DX-ing goals left as far as chasing awards goes:
- DXCC on 160M – very much do-able, and highly desired
- Honor Roll #1 – just working towards it is fun – not sure it will be possible any more – I have serious doubts, but will keep “slogging”. I still get very excited about ATNO’s, but also feel “safe” knowing my main goal of mixed HR is now in the bag – and the plaque is on the wall. I really worked hard and fast for that one!
I have way too much fun just goofing around to bother chasing all of the stuff that others chase – but its fun to have a couple “activities” to be involved in. These help motivate me to continue tweaking and tuning my little pistol antenna farm . . . and keep me from losing interest (and I have competing hobbies that surely are taking more time away from ham radio these days).
Since DXCC HR #1 will no doubt take at least as long as it took to earn regular mixed Honor Roll (11 1/2 years), its not worth worrying about – or knocking myself out for. I’m lucky to work one or two ATNO’s a year at this point – sort of like watching the grass grow.
However, 160M, besides being just great fun (why we do this hobby, right?), is very much achievable and attainable. It will be one DXCC “endorsement” that I will be very proud of too. So this is where my “active particpation” lies.
I did an analysis and found that the “last 40″ that I need can come from these highly probable areas of the world (basically the area on the map above):
- Asia – 10
- OC – 23
- SA – 15
- Carib – 12
One thing I just realized – working SA on 160M should be done NOW – as far as where the grey line line’s up – except – the summer thunder storms create serious noise – and for whatever reason – there don’t seem to be many SA stations on 160M.
This won’t be a fast and furious trip – I expect that it will take at least 3 more years to accomplish – probably more like 5. In fact, DXCC on 160M will probably take at least as long as it took for me to get to regular mixed Honor Roll. The main reason is the number of entities who activate 160M – and the DX-peditions that bother with it (and actually do it well!).
I have one antenna project this summer – to modify a Cushcraft MA-160V to work primarily on 160M and 40M, with 30M being secondary, and 80M just a passing thought. I’m fixated on trying to reach my DX-ing goals with two antennas – my 3 element 20M yagi is just the best high band antenna I have ever had – by a big margin, and now I want to modify my 40M 2 element Christman phased array to work as a 40M array and also be able to switch to one vertical (or both – both not being phased) for 160, 80 and 30M.
I’ll report back if I can multi-band the MA-160V to match my design goals. If not – I will keep the three that I have – 63′ 160/80M vertical, 40M array that also works as a phased array on 30M (sort of), and the 3L 20M full sized yagi.
I expect that I will succeed on 160 and 40 – but at too severe cost on 80, and maybe 30M. But I still feel the need to try – it would be way too cool if I can pull this off.
Why am I doing this crazy antenna project? To minimize the interaction between the tall vertical and the 40M array. But at some point – you get to “as close as” you can as far as optimizing an antenna farm on a small lot. This summer – I will have completed this process, and it has been much more of a learning opportunity than I had ever expected.
June 29, 2014
I had what seemed like a great idea, and that was to replace my tall 63′ top hatted and loaded vertical with two Cushcraft MA-160v’s. My idea was to “only” care about using both on 40M in my 40M phased array, and then switch and use just one of the two for 160, 80 and 30M – thinking that would be “good enough”.
The extra height of my modded MA-160V is significant. By adding 30′ to the base of the MA-160V, I decreased the loss (increasing gain) by a very noticeable margin – almost 6 dB.
On 80M, using the “stock” MA-160V would be a disaster – unless I modified the coil and or hat arrangement. At first I thought “I don’t care about 80M anyway”, but now realize that since we are starting to slide back down Cycle 24, its best to have the best you can on the low bands.
On 40M, using phasing the two for 40M is essentially the same as using what I have now – which are two 24′ top hatted verticals tuned for 40M. I get 4 dB end fire, 3 dB broadside gain, and with 18 dB F/B in the end fire directions. Using two “stock” MA-160V’s but tuned to work on 160 and 40M would work just fine – and be about what I have now, which is a pretty interesting idea.
On 160M, switching to one “stock” MA-160V – would work just fine – but I would be getting single MA-160V performance – which is noticeably down from the 63′ “modded” version of the MA-160V. I’m not excited about this – or losing 80M almost altogether. I even did a test on 75M with members on The Mission Trail Net, and they said the modded – tall MA-160V was almost twice the signal strength of the “stock” MA-160V. I am sure this is because adding the extra length of tubing under the MA-160V gives me a true (almost) 1/4 wl vertical on 80M.
On 30M, the gain is “close enough”, but I raise the take off angle from 20 degrees on the tall 63′ modded MA-160V to 25 degrees with a stock MA-160V.
So – this idea does work to a point – but it underscores what happens any time you try to multi band an antenna – you have to accept compromises.
ON AIR TESTS
On 40 and 30M, the receive and transmit between my 24′ hatted verticals and a “stock” MA-160V are in fact about the same. This means you could phase two MA-160V’s on 40M and you even get a little “sympathetic” end fire and broadside gain and F/B on 30M – even with the Christman feed for 40M. I’m guessing its more a parasitic array on 30M, but that is a big pleasant surprise.
I might even be able to accept the degradation on 160M – since my only goal is to make DXCC on 160M – and I have 60 entities already in the bag. I could easily make it if enough Caribbean and OC/PAC/Asia entities would activate on Top Band – probably even with “just” the stock MA-160V.
The biggest problem is 80M – it is pretty much rendered useless, and I’m not ready to give up a band that – during the morning grey line – could make the difference between working entities that I need – like FT/T or not working them. FT/T is most likely on 40, 30 and 20M, but even local net checkin’s are eliminated on 80M – so . . . .
The good news – if you are on a small lot and want a decent antenna system that is 36′ tall and you want “OK” performance on 160M, “Good” performance on 30M and “Very Good” performance on 40M – then phasing two MA-160V verticals using a 40M Christman feed might be for you.
Since I can have a 63′ tall vertical and I really do want DX performance on 80M, I will keep what I have, which is the 63′ tall modded MA-160V, the 40M phased array and the 20M 3L full sized mono bander – with its 16′ boom.
I will test a single MA-160V against my 63′ modded MA-160V and also compare it on 40 and 30M against the 24′ hatted verticals that I have in my 40M phased array. I will use the Reverse Beacon Network and other on the air tests – mainly to see if any new ideas pop up.
I have started to look at two MA-160V’s (stock) and modded (63′) spaced 50′ – which is what I can do easily on my lot – and play with different phasing schemes. At first glance – I’m seeing some interesting things. I’ll write up a follow up blog to this one – because I still think a decent antenna idea is lurking here . . .
June 26, 2014
- Tired of your small concealed HOA restricted “RF Weapon of No Particular Destruction”?
- Tired of getting RF kicked in your face in pileups?
- Tired of waiting until the last day of a DX-pedition to hopefully grab the last few “Q-crumbs”?
Then my Friend, you have come to the right web page. We are “L.O.A.D” – or The League Of Armchair DX-ers!
The only thing you need to do to join LOAD is recite “The Oath”:
- Non sum dignus (I am not worthy)
- Non sum dignus
- Non sum dignus
And Finally – Recite “The Little Pistols Lament”:
- Expectabo meam (I will wait my turn)
- Quando locutus loquar (I will speak only when spoken to)
- Quantum ad regem socnero (I pay my respect to the King)
- Et dabo primogenitum meum pro card QSL (I would give my first born for a QSL card)
The logo is an attractive symbol – similar to many others – but with a distinct difference:
And you automatically qualify to join “S.O.C.K” – The Sub Optimus Contest Klub:
Have a great Field Day or fun at Friedrichshafen . . .
June 21, 2014
Summer Solstice is here, and “the livin’ is easy”. Things are going great all the way around at work, play and everything in between.
Unless there is an unprecidented third peak in Cycle 24, I think we are starting to slide down the cycle. The good news is the decline is “slow enough” – so conditions should be pretty good for the next 3 years or so.
I expect to work 4 of the 8 ATNO’s that I need towards DXCC Honor Roll #1 – in the next 3 or 4 years – so that will be fun. I’m more than OK with the fact that the ATNO’s only come one or so a year – I’m in no rush – like I was to make Honor Roll – and now I am enjoying the hobby with no stress – just fun.
On Tuesday, the days start getting shorter – but only noticeably by August or so.
The antennas are now set, with my concentration on 160M, 40 and 20M – and with mono banders here. Since I am not chasing DXCC Challenge – I am having a LOT more fun with these mono band antennas. Luckily, the 160M 63′ vertical does a superb job on 30 and 17M as well – so I am very well covered for where we are in the cycle through the bottom.
I think I will work on a new art piece and also put siding on the two sheds out back. Between these projects and gardening and mountain biking – and working on VK0EK (and oh yeah – working full time), I think I know exactly what this summer will look like.