Posted on October 30, 2017
When I started DX-ing in 2001 I had only wire antennas, and I made it to 300 with just wire and 200 watts. AT about 275 it became so difficult that I put up an Cushcraft MA5B then a Force-12 C3SS. BTW – I worked P5/4L4FN with 200 watts and that MA5B . . .
When I started I had a low dipole on 40M, but when we hit the bottom of Cycle 23 I got more serious and put up Christman Phased verticals on 40M. That difference was just like the difference going from a low wire to a 2 element yagi – as far as results are concerned. I am sure that a 2 element yagi up only 50′ is a bit better than phased verticals but maybe by 1 dB – not enough to worry much.
40M is my second highest total band. Since with Mixed Honor Roll, I worked an ATNO wherever I could. I did not start out trying DXCC Challenge, so in the beginning I would work an ATNO on one band and try to work them on another band or mode for an insurance QSO. If I were chasing DXCC Challenge, my 40M woul be a lot closer to my 20M totals.
But now that I have been through one full cycle – almost a cycle and a half – I realize that it is very possible to work DXCC Honor Roll with just two verticals, a phasing box and some coax. And furthermore, getting to 100 on 160M – with VK0EK, FT5ZM and three African stations in my 160M totals – reminds me that verticals are very good antennas.
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.