VK0EK: A Year After

•February 28, 2017 • Leave a Comment

vk0ek-banner-update4_10-qrtsign

Its been a year since the team embarked on their mission. It was very successful, and they ended up with statistics similar to K5P – who had many of the “regulars” who were on the K0IR and K4UEE DXpeditions. Besides the numbers, we ended up with the ARRL’s QST Cover Plaque Award:

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And a full edition of DX Magazine:

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And new friends whom I still correspond with. I gave the Keynote Presentation last year at Visalia and had Bob, KK6EK phone in from the Braveheart via satellite. The experience was so good it has become a major “prize” on my LinkedIn profile and resume. It has really made a difference in my career – something I never expected. Of course, I also got within 2 away from working them all DXCC wise and had the Best QSO Ever on 160M – perhaps the last QSO to make Top of the Honor Roll will beat that? But DXCC and ham radio wise – it signals the end of an era, but started the new era that I am in – which is tripling down on the low bands. I decided I will wait until next December to put up my 2 element 20M yagi – it will be stored safely under the house waiting for 3Y0Z. I truly have had the most fun ever in ham radio since about last July – when I started really digging in and being a lot more scientific about designing, building and testing antennas.

One of the things with VK0EK that drove me harder than ever was having an antagonist nipping at our heels like a little ankle biting dog.

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I was on my bike – so I just pedaled harder and faster. That person will never know how much he helped me do my best and make VK0EK Happen 😉 That also only enriches the story – so thank you Mr. Antagonist!

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I’m not going to Visalia or Dayton this year – it will be Bob’s turn around the final victory lap, and perhaps some team members too (I hope). My work on the project was done a long time ago – and I have moved on. The project that took 3 years in the making seemed to come and go so fast – not unlike my kids growing up. Projects and events like this in life have a way of “marking” time. DXCC Honor Roll was a big one for me. Some (but not all) of my jobs in my career were that way as well.

I’m always forward thinking and have moved on – I won’t be doing another one – that experience was enough to inform me on what they are all about – and that’s enough for me.

 

Fun With Feeds!

•February 27, 2017 • Leave a Comment

20m-hsq-phased

The antenna that I have been modeling and which I have built is not technically a “classic” Bobtail Curtain – on any band. The spacing would be a 20M Bobtail – but with 43′ verticals, they would be 5/8 wl, and a Bobtail really needs 1/4 verticals. It can’t be a 30M Bobtail because that means the verticals would be 24′ tall and the spacing would be 48′ between each vertical. On 30M, the verticals would be just under 1/2 wl and the spacing would be 3/8 wl spacing.

However, the fun thing about this antenna is where it can be fed – which is at the base of the four bottom points of 1, 88, 89 and 46. On top of that, 88 and 89 can be connected as well. In each scenario it works best for one or more bands. Here are some interesting feeds to try based on modelling:

FEED 160 80 40 30 20 DX SCORE
88+89 as Doublet 20 deg

.76 dBi

Omni

25 deg

5 dBi

E-W

20 deg

4.4 dBi

E-W

15 deg

8.52 dBi

E-W

35 deg

5.28 dBi

E-W

5
88+89 Fed Against Ground  

90 deg

-8.37

Omni

90 deg

5 dBi

Omni

20 deg

-14 dBi

N-S

15 deg

2.49 dBi

SW – NE – SE – NW

25 deg

1.46 dBi

E-W

2
1 and 46 20 deg

2.48 dBi

Omni

20 deg

1.98 dBi

E-W

20 deg

5.15 dBi

E-W

15 deg

3.69 dBi

E-W

45 deg

5.35 dBi

E-W

4
1 and 89 30 deg

2.14 dBi

N-S

20 deg

3.51 dBi

E-W

45 deg

4.87 dBi

E-W

30 deg

7.77 dBi

E-W

40 deg

6.99 dBi

E-W

2
1 20 deg

2.43 dBi

N-S

85 deg

2.87 dBi

E-W

20 deg

4.11 dBi

E-W

30 deg

8.09 dBi

E-W

30 deg

4.21 dBi

SE

4

 

The very clear winner is the feed I have right now (88 + 89 fed as a doublet).

I’ve decided to stash the 20M two element yagi and only put it up when 3Y0Z or Glorioso comes on the air. One thing that is abundantly clear – radials introduce loss – no matter how you slice it. The doublet style feed – with the verticals above the radials and nothing connected to the radials wins every time. But the ground screen still helps for sure.

This antenna is very good on 160 – 30M. It is not even as good as a dipole on 20M – but is as good as a dipole on 30M. On 40M it sometimes is better than the broadside position of the DXE phased array, and on 160 and 80 – that’s where is really shines – since there is no way I could put a dipole up on those bands.

On 160M the only gain comparison can be between a single vertical and this antenna – and it does have significant gain over a single vertical. Same for 40M – but I have had a better antenna before that was only up 50′.

When 3Y0Z comes on the air – if I do put up my 2 element yagi for that month they are on – I can use that on 20M and 30M – and they will beat any vertical that I have in my arsenal.

 

 

 

The Whale

•February 27, 2017 • Leave a Comment

20m-hsq-phased

I did not realize that when I modeled the different feed of my 30M Bobtail that I was actually phasing two 20M Half Squares in Line – using the Christman Method.

hsq-phased

The feed will be one lead (short), and one lag (long) giving 84 degrees . . .

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The Whales two “eyes” are the forward lobes that point almost perfectly towards 3Y0Z on the short path and Glorioso on the Long Path. Because FT/G will no doubt be activated at the bottom of the cycle – the Long Path will be my only hope (unless I “cheat” and use an East Coast Remote). I certainly wouldn’t want to use a remote – and finish up my DXCC Award chasing “the old fashioned way” – with my own antennas – mostly built by me, and always in my own back yard.

20m-bob-phased-az

From above, the patterns are exactly where I want them. This pattern is documented in the ON4UN Lowband book on page 11-3. The reason the pattern is “funny” like this is because the elements are both just over 1/2 wavelength tall. I can’t use the VA7ST Christman calculator on this one because the spacing is wider than 1/4 wl on 20M. So the AC6LA calculator will do the trick – because he gives you several sizes that will work:

ac6la-20m

I will only need two phasing cables and a 239 “T” connector. I won’t even bother trying to build an exotic switch – because the feed for the Bobtail is so much different than the feed for phased 20M Half Squares. Access to just change coax connections will be very simple – and so it will be “arm strong switching”.

20m-hsq-parasitic

If all I did was feed the number one vertical – on 20M it becomes a parasitic array – end fire – with Half Square performance and a decent null off the back. Its not nearly as good as the Christman phasing – but it is a very viable option. So – there are many options here, and this 30M Bobtail Curtain is turning out to be the most interesting and flexible antenna one could hope for for DX-ing 160 – 20M.

 

 

 

Feeding the Bobtail for 20M

•February 27, 2017 • Leave a Comment

20m-bob-feed

Just by playing with the feed of the 30M Bobtail, I can get it to work quite well on 20M – and pointed towards Bouvet – 3Y0Z. Instead of feeding wires 88 and 89 – which gives me broadsided Bobtail on 30M, if I feed element 1 and 89, I get the same gain as a dipole up 1/2 wl on 20M.

20m-az-newfeed

If I phase the two, then I will get some serious end fire F/B and decent gain:

20m-bob-phased

And the directions will be exactly toward Bouvet (short path) and Glorioso (long path):

20m-bob-phased-az

Gee – maybe I don’t even have to bother putting up the new 2 element 20M yagi. Sure – it would be better, but not so much to be like night and day. The phasing is dirt simple – since I can do a straight Christman feed and use the Stackmatch II.

 

S01WS on 40M

•February 27, 2017 • Leave a Comment

s01ws

Beautiful opening on 40M to Western Sahara about 2 hours before sunset (0025z). DX Atlas says the path is 58 degrees from my QTH, and so the vertical in my 40M phased array in the NE direction is right on. The Bobtail is dong fine – but the phased array does win – not by a huge amount, but if you asked “Quick – choose an antenna”, it would be the phased vertical array. However – I’m very pleased that the Bobtail is very much in good stead here. Mainly because its the first time I’ve had a Bobtail that worked as modeled  . . .

I can really tell that we are closer to the bottom of the cycle than we think, because this happened during the last bottom of the cycle – more and more – 40M started sounding like 20M. And that has been the case now for quite a few months.

I’m going to predict that 3Y0Z will herald the bottom of the cycle, and that it will start right about when 3Y0Z comes on the air, and really bottom out during 2019 and 2020.

2019 and 2020 and maybe even 2021 will be GREAT for 160M, so that’s the best part of this.

If I only have 160 and 40M from now on – I’d be in heaven . . .

Tuning the 20M Yagi

•February 26, 2017 • 2 Comments

The 20M yagi being tuned on saw horses. The elements are very well balanced. It’s surprising how big a 2 element 20M yagi is. The boom is 7.5′ and elements in the 30 foot range.

The Balun Designs 1:1 current choke and hairpin coil.

Rig Experts AA-30 and laptop for testing the feed and hairpin.

It’s hard to believe the first coil I tried (re-purposed from another antenna project) is right in the ballpark. I will check this again with the reflector on saw horses next to my deck and with the director straight up. If I need to tweak the coil – it will be a snap.

I’m guessing the antenna will go up this week one day. I’m taking my time to measure and test along the way – in the past I would have been in a big hurry, but 3Y0Z is a little ways away – heh heh.

20M Yagi Built!

•February 26, 2017 • Leave a Comment

This is what my 2 element 20M yagi looked like at 11:30 am this morning.

And at 3:30 pm.

The aluminum cost me $138.00, and I already had the boom, boom to mast plate and boom to element brackets.

I’ll just add my Balun Designs 1:1 choke and it will go up tomorrow – if the weather cooperates.