November 27, 2014
Its Thanksgiving – that means its time to build the next antenna at KY6R. I am going to take the three elements from my 3L 20M 16′ boom mono bander and move them to a 30.5′ boom that will have 4 elements on 20M and 2 elements on 30M:
The antenna will be up 50′ and will be trussed. Each joint will have an extended piece of double walled aluminum to ensure strength, and will be bolted in two places – at right angles to each other.
I have all of the DX Engineering plates and resin blocks, as well as the boom to mast plate and clamps and stainless steel U-Bolts. I even have two cast aluminum truss brackets for the boom.
My design has both bands at 1.1:1 SWR – on 30M its flat across the band, and on 20M its the classic “V” curve, with the lowest SWR centered on 14.175 mhz.
The ERP figures are impresive:
20M – 18.3 KW with 1.5KW into the antenna. Loss not included in this calculation.
30M – 1.5 KW with 200 watts into the antenna. Loss not included in this calculation.
I will probably also have a loaded 40M dipole running just above the boom, so that I can use this antenna on 40, 30 and 20M. I already know this will cause no negative interaction, and I will be able to finally test my 2 element phased vertical array against a dipole up at 50′.
Happy Thanksgiving – I am going to build this for the K1N Navassa DX-pedition!
November 26, 2014
I’ve been toiling over trying to design a 40/20M yagi, and the element size on 40M would require coils – and I just don’t want that many possible failure points up in the air. So instead, I think I will (finally) give up on that idea and try a 30/20M yagi. I’m finding that a “modest” 26′ boom can work for a 6 element 30/20M yagi – 4 elements “OWA” on 20M and 2 elements on 30M. The usual “stagger forward” design is employed:
One really nice thing is that I already have 26′ of 2″ boom material, and it would be a piece of cake to take the 3 elements I have up in the air, transfer the elements to this new larger boom, and then add one additional element for 20M and two new elements for 30M.
On 30M, at 25 degrees, there is 11.43 dBi gain – or roughly 3 dB. I’d like to squeeze out another dB, but I don’t think this will happen. I will keep modeling and trying. Some F/B would have to be sacrificed.
The Front to Back is 21 dB – which is GREAT.
The 20M pattern looks normal, and I’m tweaking the model to try to get to 13 dBi. I’m at 12.21 dBi gain now – but I am sure I will get to that 5 dB gain figure with some more futzing.
The F/B on 20M right now is only 14.26 dB, which certainly needs to come up to maybe 18 dB.
Lets look at what the ERP figures would be if I can get these gain and F/B figures:
At 11 dBi (3 dB gain), 200 watts ends up with 1.5 KW ERP
At 13 dBi (5 dB gain), 1.5 KW ends up with 18.3 KW ERP
I still have some more tweaking – moving the elements around and tuning them, but I am sure that with a boom as short as 26 feet, I can come close to these design goals. And this antenna will be a great performer on two of my favorite bands, and then I would have mono banders with gain and directivity on each. I’m guessing this makes me quite competitive on all of these bands.
November 25, 2014
Photo Courtesy of the Quartz Hill User Group (Wellington Amateur Radio Club Inc.) . .
This is a full sized 5 element 20M wire yagi at the ZL6QH – Quartz Hill Contest Super Station in New Zealand. I could fit such a beast in at my QTH in the two directions where I need the last 6. I could even modify this idea and build a 40 – 20M version of this. Here is the Quartz Hill web site page that has this behemoth:
It is 78′ long and the reflector is 35′. The gain is 6.8 dB, or 15 dBi. With 1500 watts, the ERP ends up being 29KW!
I have a very nice Blue Spruce tree in the front of my house – where I could get this antenna up 70′, but in the back yard, the support would be about 60′ – due to the slope of my property from front to back. So – 60′ would keep it level. The ZL6QH group had theirs up at 50′. Here are some ways I could lay this out:
I even have a great way to elevate and hold the other end of the antenna – I would take down my aluminum yagi and move the AB-577 away from where it is now and nestle it behind a tall and strong cedar tree. It wouldn’t need to be guyed at all – as the pull of the wire yagi – would cinch the AB-577 mast up snug against and in the branches of the cedar. That is where the “green circle” is. I could also put it against my house on the side – and then have guys going down into the creek area – and tie guys to several very strong and tall trees.
November 23, 2014
Right now I have a full sized 3 element 20M yagi up 55′. I just read an article where a ham in Napa has been ordered to crank his tower down to 21′ from 6 AM – 6 PM. This pretty much wipes out the high bands – except in summer when 20M stays open past sundown.
I started thinking, “What would I do if I was given such a rediculous rule?”.
The first answer is – I would still be just fine on 160, 80, 40 and 30M. My verticals – which you can’t see from my street are good DX antennas. But 20M is THE money band, so what would I do there?
Well, look at the EZNec traces above. An Extended Double Zepp – up only 45′ – has a great 3 dB gain at 22 degrees take off angle. I could easily move my AB-577 to the side of my house – nested in the trees and painted green, and then run two wires – one broadside NE – SW and the other SE – NW.
These would cover all directions I need for DXCC HR #1. The second good thing would be that I could also use the antenna as a very effective 30M antenna. And look at how the EDZ is as good as a Moxon (up 65′). To make feeding both a lot more convenient, and to eliminate any negative interaction, it would be better to have the two EDZ’s at right angles:
I would lose 2 dB from my yagi – but I am confident for what I need – I would still work what I need. I would not work them as easy as the yagi – and would go back to my “dark days” of DX-ing, where I pretty much never worked anyone on the first day – but maybe the next day 0 or days later, and even then – I had to spend many hours fighting in the pileups. That’s at least on 20M. On 30M – I would be as competitive as most others on that band.
One last crazy idea – a wire beam – using two EDZ’s on 20M, spaced 44 feet apart:
On 20M it looks like this:
And on 40M:
Oddly enough – 45 feet seems to be the “sweet spot”. Raising the antenna to 70′ actually decreases the gain. If I were to use a Christman Feed on 40M (rendering it a 40M monoband antenna), look at the incredible F/B ratio and pattern:
The gain is very modest, and the takeoff angle a bit high – but the F/B is crazy! Since going this route – I can actually add 20′ to the top of the AB-577 without issue – lets raise the antenna to 70′, but bring the spacing in closer – to 22′ apart:
With 135 degree phasing we get:
and on 20M:
Not bad at all for wires in the trees!
The wires and the mast are either green or black – meaning they more or less blend in to the surrounding trees. Where there is a will – there is a way. Another reason why I would much rather have my olive green AB-577 – which is VERY low profile instead of a giant 3 legged shiny metal tower.
November 21, 2014
You can find the new Radio Arcala DX Summit web application here:
The Radio Arcala Group have done a great job updating their world famous DX Summit DX Cluster web application. It now is in the same “modern” space that DX Heat is (which I have reviewed in an earlier blog), and it offers some differences that are quite note worthy – and unique.
Setting filters is very natural and easy to understand. You can include or exclude bands and modes by clicking on buttons – and these are saved on a sort of “palette” for you at the top. My favorite feature – and one that I used extensively for the FT4TA DX-pedition is the ability to filter by either a DX or a “DE” callsign. I am 6 entities away from DXCC Honor Roll #1 and the only two awards I care about are DXCC HR#1 as well as 160M DXCC. I also only care about mixed awards and the CW and SSB modes. I can filter for all of these, and this really helps me hone in on exactly what I want.
This is “Feature #1” that makes DX Summit really shine.
The result by setting the DX filter and the modes and bands in my “palette” really cuts to the quick when I am DX-ing. Fantastic! The only slight “niggle” is that there is quite a bit of “real estate” on the screen that is taken up at the top. I like the way DX Heat puts the filters off to the side rather than at the top. This way I can see more spots from top to bottom on the screen. But this is just a minor “nit”, not a big deal. By the way, you can also download a CSV file of historical spots. This is one area where DX Heat does go quite a bit farther – since it offers lots of “analytical” options to slice and dice historical spots (see this DX Heat Review in a previous blog):
Here is the second “killer feature” or “key differentiator” that I especially like. When you click on a callsign, you can lookup the VOACAP Online prediction, and just as importantly, see a gray line map (many times VOACAP Online does not do justice for low band gray line predictions – especially long path – but this is where I usually resort to my memory of past gray line QSO’s with a particular part of the world and even what I expect the conditions to be based on the time of year and where we are in the sunspot cycle. For example, I knew that FT4TA would be GREAT on the Long Path on 40, 30 and 20M. And I knew it would be better than any predicition software would show – because I remembered TO4E and with some quick research, saw that the sunspot numbers were close this past month as they were when I worked TO4E. The time of year was also similar to TO4E. So in this case, I relied much more on the gray line and gray line map than VOACAP Online.
Having said that – I really like how the integrated VOACAP Online now can use your “computers location” to set your QTH, and you can switch between long and short path, and also switch between a Basic or Super station. This means it is starting to incorporate some of the features that you see in the K6TU Propagation Prediction service. Not quite as extensive – but something really special for somthing so well integrated into a DX Cluster application.
As a little pistol, I would have to say that much of my success as a DX-er has been my knowledge and use of the gray line. Many of the most rare QSO’s and ATNO’s that I have had were in the morning or evening gray lines. I have been able to use these gray lines as a “sliver of propagational advantage” over other parts of the world that may have had much better conditions and for many more hours during the day. But for the small sliver of time – many times, the West Coast had its only chance during the gray line. So for me – this little feature is easily as important as VOACAP Online. Together – WOW – what a powerful set of DX tools. Oh – when you first visit their web page – you will be asked if you want the app to be aware of your location. Say YES if you want these features to really shine.
The QRZ.COM lookup goes right to QRZ and does a lookup – which we are all very familiar with, and the Clublog link goes to the online log of Clublog for that callsign, and you can lookup your QSO’s in the DX stations Clublog.
I really like this new DX Summit application, and I use it and DX Heat now – with two tabs in my browser running not only when I am at home next to the radio – but also during the day – when I can sneak a peek at whats going on when I am work! I don’t think one is better than the other – I like both equally – and like them both very much.
I highly recommend the new DX Summit application – it is a very powerful and useful DX Tool.
November 17, 2014
We have just passed the second peak of Cycle 24, and we are now on the down slope. We should actually have decent conditions in 2015 and into 2016, but I think 10 and 12M will be down in the number of openings, and 15, 17 and 20M will still be good. The low bands will be quite good. For the last 6 that I need, there is no doubt – 20M will be king of the higher bands. I also expect 40 and 30M to be very good – but none of the prediction engines seem to do the low bands justice. Anyway – here are what the latest predictions say about my “Last 6”:
By a wide margin, conditions will be best for K1N, Navassa. I’m very, very excited about this DX-pedition. There is no gray line advantage for the West Coast – at all.
Heard Island will be great into much of the world, but because it will be tricky for the West Coast, we will activate two locations – Atlas Cove and Spit Bay. There is a very nice opening on 20M at 1500 utc for the West Coast:
VK0EK will certainly work the 20M band clean for ATNO’s, and from both locations, using very nice yagi’s. If you look at the VK0EK.ORG site and check out the propagation pages . There will be a gray line advantage for the West Coast, and when you combine this with operating from Spit, I think the low bands will be decent:
There will be 4 squares and other phased arrays on the beach for the low bands. Basically, we will go for maximum gain and directivity on all bands.
On paper, 3Y0F looks quite good:
But there will be massive competition from EU. 3Y0F will have to ask for NA – and especially West Coast only to get us in the log. I did hear Petrus during the last 3Y0/B activation – when he had 100 watts and a vertical, so if 3Y0F puts in a great effort, this should be workable, and mostly on 20M.
There will be an evening grey line opportunity, but there is no doubt – signals will be crushing from EU to 3Y0/B.
South Sandwich should be better – in fact – should be more like 3Y0X, which was quite good for the West Coast:
There is also a nice evening grey line – very similar to the 3Y0F grey line opening.
Kingman Reef would be killer for the West Coast, and while I’d love to hear signals that strong and 24×7, forget about it. It just isn’t in the cards. I do not expect to ever hear signals from KH5K. To top it off – there is an absolute killer grey line opening for the morning for the West Coast, so working 160 – 6M would be a piece of cake – and at any point in the sunspot cycle. Now you know why I have had so much interest (and frustration) with Kingman Reef.
I expect that Glorioso will be workable – as long as it isn’t activated at the very bottom of the sunspot cycle as FT5GA was. However, at that time I only had a 20M Moxon up 30′ and now – with a full sized 20M 3L monoband yagi up 55′, I would be able to maybe squeak a QSO out. But FT5GA clearly brings back what the bottom of the cycle is like – where even 20M is hardly ever open. Not a good memory at all.
I have heard a lot of “banter” about Glorioso and the unfulfilled need left in the wake of FT5GA. Glorioso and Europa both require that the operators be French Citizens and on top of that, French Military, so these are simply not going to be activated on any kind of regular schedule. TO4E was last activated in 2003, and FT5GA in 2009. They were activated before that in 2000, but that was at the end of a long run of hams who worked on the French “Meteo” weather gear on the island. Now – activations seem to come once every 10 years at best – so I am guessing 2019 will be about the next time it will be considered. I am sure they will look at Europa before then – but who knows – anything is possible – and I have had quite a few surprises where something was activated way before I had expected it.
I do know there is a big need for Glorioso in North America – when I did a Google search, I found many DX Newsletters where the North American’s largely said that FT5GA did not seem to concentrate on NA. To be fair – conditions simply stunk – so I clearly remember propagation being really bad at that time. And the “deserving” did get their QSO – so – it’s up to each of us to improve our stations to be able to work the very rare one’s at the bottom of the cycle, eh?