Posted on October 30, 2017
WOW – that was easy, and a great validation of my new Inverted L and tuning circuit. I turned on the rig, tuned to his frequency and worked him right his sunrise enhancement. Minutes later he was gone.
OK – now I only have 10 more left to get to DXCC on 160M plus get an endorsement to get to 9BDXCC. I really do think DXCC on Top Band from the West Coast is as big an accomplishment as Mixed Honor Roll. Mixed Honor Roll took me 11 years – 160M DXCC maybe half that, but the challenge of getting a good signal out and hearing a low noise signal coming in is a big, big deal.
Posted on October 30, 2017
It took a lot longer than I expected, but after trying many LC circuit combinations, and I can make the SPE Amplifier happy on 160, 80 and 75M. Trying to add in 40 and 30M were possible, but by adding in more components and thus causing some loss – which is silly since the DX Engineering DV-40-P works much better on 40M and even works “well enough” on 30M.
I was actually able to tune the antenna to 1.0:1 at 1.822 khz and the SPE tuner easily lets me cover the entire 160M CW band, which is where I find my “DX-citement” these days
I’ve never liked 80 or 75M all that much – but if an ATNO is there, I have it covered. Malpelo is the only ATNO where I worked it first on 80M CW, and its just never been much of a strategic band – not even at sunspot minima. A simple retuning and voila!
After measuring the antenna with the AA-30, I found that the Balun Designs 1:1 current choke followed by this circuit:
I also tried the DX Engineering 4:1 balun, and while it had some interesting properties, I feel better with the simple current choke. There was some strange intermittent behavior with the 4:1, so I will skip that. It seemed to result in giving better 80M CW band coverage, but I’m guessing there was some saturation that stressed it too much, because an amplifier fault occurred after a short while sending at full power. Besides, the SPE makes up that difference anyway with its built in ATU. I’ll take safety and stability over lower SWR but instability any day.
The Spiderbeam push-up mast as Inverted L vertical.
The far support for the Inverted L wire, it is 68 feet away and the rest of the antenna wire drops down from that support. Theoretically, I pick up almost 1 dB gain by not using that mast where the antenna used to be an Inverted U. It’s very interesting how the tuning changes between an Inverted L and an Inverted U.
One bit of sad news, a cheapie Chinese 12v / 5v step down unit burned up and took out my Raspberry Pi Zero W, but I have a spare to press into service. Since I am on 160M 99% of the time, I might not even bother. Less is more when you have high power . . .
I’m getting good on air signals, and with just some very slight tuning, I can get 160M down to about 1.06:1 and 75M about 1.5:1.
With just one test message I was picked up quickly from the East Coast to Hawaii – and it looks like with a strong signal.
OK – all of this work seems to have paid off – now – when will I get to 90 DXCC on Top Band?
Posted on October 29, 2017
From Page 6-8 of the ARRL ON4UN LOwband DX-ing Book
Today I will nail the new LC circuit for the Inverted L. There are 14 combinations that I can try, so it could take a couple hours to finalize the LC circuit, wire up the u.RAT and button it all up. The ones that have one L and one C in the diagram above will be tested as will some other circuits, such s series LC with different order of components, and I will even try a few with a third fixed component since I do not want to add another stepper motor or some switching network (which would be easy, but I’m lazy).
There were 6 entities spotted during the CQ WW on Top Band that I needed but all I worked was V21B, and I am at the mercy of having my KW6R busted call fixed – unless they got it right when they faded in the QSB – which is very possible. Right now I’m up in the middle of the night and daylight is just starting to hit the Caribbean, so unfortunately, the crummy conditions this weekend on 160M just didn’t cut the mustard for me.
Lets hope that the CW portion of this contest bears more fruit – it would have been amazing to have gotten to 94 in just one weekend – but it at least shows that I need enough in the Caribbean, South and Central America to get to DXCC – so it should be easier than this.
The best news is even being heard and hearing V26B. I beat several much bigger guns with better QTH’s and antennas, and my RX situation is better than average. Hey – so is my TX antenna, although an Inverted L isn’t the most impressive antenna, but it does the trick.
Posted on October 29, 2017
I now have the antenna in this configuration (128 feet total length), and also have the u.RAT ready to be set into it’s waterproof box and wired up.
The fancy schmancy u.RAT control console
Because I have a shorter antenna with the far end up off the ground, 160 tunes well, but 80M now tunes at a 3:1, so I will probably have to change my wiring at the feedpoint a bit. The SPE amp with built in tuner handles it just fine – but I liked how easy it was to tune the Inverted U yesterday … But I’m going this route to get 1 more dB and a lower takeoff angle. Its worth some extra work.
Ed, AG6CX stopped by to pick up the Palstar BT1500A tuner – and we had a nice chat. Ed has built some really awesome antenna tuners and shares my love for matching antennas and with high power. He gave me an amazing coil – who knows – I might put it into service tomorrow to get this 160 / 80M match to sing.
For tonight’s contest on 160M, I’m tuned up and ready to roll. I’m praying conditions are better tonight and tomorrow morning – so I can get a really solid V26B and 9Y QSO and get to 90 with confidence.
Tomorrow I will take measurements with the AA-30 and see what’s going on. I need to see what the impedance is on 160 and 80 and also see the SWR curves to hopefully see that they are narrow banded. This will ensure that my radial field is not an earthworm warmer.
I will try these things:
- Classic LC tank circuit
- Other LC combinations
- Just a series capacitor or inductor and on both antenna and radials
- Roller inductor as hairpin match
- Add in a static inductor somewhere – or even a doorknob cap somewhere
It is very interesting what happens when parts of your antenna are close to ground. This was a more radical change than I expected, but it does show how critical the effect of your ground is on your antenna(s).
Happy Halloween – bring on the Witch Hunt, and burn them at the stake!
Posted on October 28, 2017
Top Band is a nostalgic band – it being just above the AM Radio Band.
This one was a really tough one. He was very strong, but rumor has it his Beverage antenna was pointed NE, and he wasn’t working anything out West. He did hear me as KW6R, but I think he did get my call right in the end – although (and of course) he took a deep fade at the point where he seemed to finally get it. This when I wish we were using CW . . .
This unequivocally proves that even though my antenna needs a tweak today, its getting through when contest stations out west weren’t – which is pretty awesome. I also was hearing very weak stations come back to big stations like W0AIH where he didn’t hear them come back to them – which also proves that my DX Engineering DV-40-P is an awesome RX antenna. At some point, after I make #1 HR, I will just use that antenna as an RX antenna on top band.
I was surprised when at least 3 other really big gun contest stations were completely missed and seemingly ignored. I must have timed it just right. He did stick with me for a while though, so even if it is a busted call, I do believe this one will count. I will keep trying – and hope for better conditions soon.
There is at least one other contest station where I need it as a counter (9Y), so I might get to 90 this weekend. Fingers crossed. Maybe tonight or tomorrow morning? I’m up just through their morning “enhancement”, then back to bed.
I will be out back in a few hours finalizing the outdoor portion of my Top Band TX antenna project, and I’m sure will get the control box and final code tweaks done this weekend. If I am really lucky, I will end up with only one component – roller inductor as a hairpin match.
Posted on October 27, 2017
My friend Andreas, N6NU has been kind enough to “peer review” my meanderings through LowBandVille. After yesterdays discovery that I can get 160 and 80M to work very well with the Inverted U, Andreas suggested that I only bring the far end of the “bent over” Inverted L so that it is 15 – 20′ above ground. Since the Inverted U was too long, I followed his advice, and with a quick and dirty model confirmed what he found – that keeping the far end off the ground drops the take off angle from 45 to 30 degrees and adds in almost 1 dB of gain.
I will drop the takeoff angle from 45 degrees to 30 degrees and also pick up almost 1 dB gain . . The loss showing is a bit worse than I expect it really is since I only have modeled one radial underneath. WHen I use my AA-30 and look at the SWR curve – if I find that the curve is fairly narrow banded, then the ground loss is not bad. If the curve makes the antenna SWR look a lot more broad banded, then its time to see what I can do radial wise. Fingers crossed . . .
Furthermore, Andreas just uses a hairpin match across the radials and vertical – so I must try this when I get home. If I could use just the inductor to match the antenna on 160 and 80M, that would be awesome!
Thanks Andreas – I feel like this is the best 160M TX antenna I could put up on a small lot.
The Mod Bob was a very interesting antenna if you have small space and want 160 – 30M in one antenna, but if you want best performance on 160 and 80M, then the Inverted L rules. I also learned why – although it seems easy to try an Inverted U – that the far side should not come so close to ground – and that its no more convenient support wise than to just fold the wire down and keep it 20′ above ground.
Finally, I like this solution much better than severely shortened antennas where you use hats and coils or other top loading because the antenna will stay up – and the voltage isn’t as severe as a really short vertical. I had experienced enough arcs and sparks on very short 160M antennas to stay away from that territory. And also – getting something up high that is strong and can withstand winds is also another design parameter where I had to experience and do the best I can on my small lot. I’m quite happy with the fact that I’ve gone “full circle” on the RX antennas, and now am closing in on wrapping up the TX antennas.
Posted on October 27, 2017
The u.RAT will be put into service – now that I have switched to the Grounded Loop / Inverted U low band antenna
On the left, the Spiderbeam aluminum mast used as a vertical – with Alumox between each joint, plus two hex head socket bolts and the clamps that came with the mast. On the right – 41′ of DX Engineering aluminum – Alumox and pop riveted between sections using short “fast taper” sections.
I was able to get several of the push up masts from VK0EK during a warehouse sale at a good price. I’ve used two of them for verticals for the past year. Yesterday it took me much longer than I had expected to collapse one (one on the right not in this picture), because when Alumox gets old it causes galling because it dries up. I think I should have not used Alumox – and just relied on the bolts and clamps instead.
Anyway, I replaced the Spiderbeam mast that was on the right with this center DXE mast, and that was a great idea because it was much lighter and easier to put up. The job at hand was to take the two wires from the Mod Bob and join them – making an Inverted U antenna – with the top wire up 41′ and 70′ across. The Spiderbeam mast will be used to replace a shorter one that holds my 2 element yagi – in fact, now that I have this mast freed up – I can move the yagi to a place where I can get the antenna up 50′ – so big “win – win” . . . I will clean the mast up and use some kind of lubricant – maybe like graphite – so it will work as a pushup mast again.
This is my “mash up” control box for the u.RAT.
Inside the bottom of my funky but in a weird way – cool control box is a 12 / 5v converter, a switch and on light. It also has a terminal block for the control line connections
I was able to drop the new control line down into the shack and will pull the cable after work today in preparation for getting everything finalized on Saturday.
I still have to experiment trying to get the Grounded Loop to work – maybe using the u.RAT tuner instead of the Palstar BT1500A will do the trick – but if not, I’m already quite pleased that I have found a great solution already. On the air last night on 80M SSB I was told that my signal was excellent in many Western States, and I did hear DX on 80 and 160M. I think RBN was down – no spots on any band were posted, and I know 40M is a place where I easily am always picked up. I had a really strong QSO with Bill, ZS6CCY on 40M SSB – SP – he was over S9, and he said my signal was a solid S9 as well. On the ON4KST Chat this morning, others lamented the same thing. It still seems dead this morning.
So, now I am entering the final phase with only a few things left to do:
- Finish the control cable pull and wire up both ends
- Test the Grounded Loop to see if the u.RAT can handle it – possibly experiment some more with LC circuits
- Hang the weatherproof box and u.RAT on the new feedpoint vertical post. I need to replace that second capacitor with the inductor that I originally had on the board. That’s easy – and I have some minor other re-wiring to do
- Look into tweaking the u.RAT code – micro step and get the tuning to be a bit faster with the KPOD
The hard work was yesterday, but it was a nice “indian summer” day – after a cool spell we have had almost a week of 80 degree temperatures, but the forecast is 20 degrees cooler starting Sunday – and 10 degrees cooler tomorrow. It even hit 90 one day this week. I do expect that this is the last hurrah – and all I can say is we have had a consistently warmer Summer and even Fall – and there was a lot less fog this summer than usual. Now that I ride to and from work every day I actually seem more acclimated to the weather than I used to be.
I forgot to mention – I met Wayne, N6KR from Elecraft – he was the last presenter, and I told him about the u.RAT and he was very excited and was hoping that some would find another use for the KPOD. I had quite a few people give me very nice feedback and compliments on my presentation, and it was more fun than I expected. I usually give my presentation early and then leave – it was fun to hang for the entire seminar.
The ARRL wasn’t interested in the u.RAT or Mod-Bob articles I had hoped to be featured in QST, but Pacificon gave me all the validation I need – plus some great feedback this week on this here blog.
Most importantly, after all has been said and done – I have a real use for the u.RAT – and exactly as I had originally mounted the C and L components on the plywood “demo board”. That’s a cool feeling – the u.RAT was almost left for dead . . .