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 . . .
Posted on October 27, 2017
This low pass (??) circuit lets me get on 160M CW and 75M SSB with very low SWR and no tweaking. I would need to tune when going down to the CW portion of 80M. The Variable Capacitor is a Palstar C600 and the Roller Inductor is a Palstar RI-28. I tried quite a few different L circuits (all of the 8 documented in the ON4UN book that has either two caps and an inductor one cap and one inductor and two caps, but this configuration seemed to work the best.
Right now I am just feeding in the lower left hand corner an its an Inverted U. As you can see – the total length of the “vertical” is actually 148′ – so its longer than a quarter wave on 160M, but not by much. This means its also about 1/2 wave on 80M, and I was surprised that 160M had a very low SWR – 1.06:1 and on 80M – with no tweaking of the components it is 1.5:1, and both are well within the Exper SPE 1.3 K amplifier, which was my design goal.
It would be nice to tune 40 and 30 as well – but just getting 160 and 80M was the absolute must. 40 and 30 are just “nice to haves”.
I don’t really know what is exactly going on – but am happy with the results. Because my 96 buried radials are mostly way too short – with only about 20 that are 50′ long, maybe the inductor tunes them since they are all kinds of crazy sizes and while they do fan out in most directions, its a crazy pattern. Maybe the capacitor on the vertical element takes care that it is a bit longer than a 1/4 wl on 160M and bit longer than a half wl on 80M.
If a reader can explain this – I’d appreciate it. I did not find anything regarding this in the ON4UN Low Band DX-ing book.
Unless someone warns me that what I am doing is not such a good idea, I will go with the u.RAT – because it is needed to cover the CW and SSB portions of the bands. I will try the grounded loop with this tuner – the Palstar BT1500A did not like it at all.
Because I have a great 40M array – I don’t have to worry much about matching this Inverted U to 40 or 30 – I found out that the 40M array works great on 30M and the SWR is already low. But still – it would be really nice if I could.
Posted on October 26, 2017
The Chinese Pistachio tree is looking like a neon pumpkin these days, but the leaves seem to be falling quicker than last year.
All the colors of fall in one tree . . .
Orange on the sunny side, yellow on the shady side
I never get tired of this – like the ionosphere, its one of the magical things in nature.
Posted on October 26, 2017
High Pass “T” Coupler Circuit from http://www.w0qe.com/Papers/Antenna_Tuners.pdf
Trying to get 4 bands 160 – 30M (and maybe even 20M as a bonus) is tricky with a 2 component L circuit, so I will follow Larry, W0QE’s lead and start with a High Pass “T” circuit – which gives great range at the sacrifice of a little loss. I plan on trying to find one position on the roller inductor and tune using the KPOD just the two variable capacitors:
I’ll move the two capacitors outwards which will give enough room to put the roller inductor in the middle.
I will first try to use a fixed inductor in between the caps using this slight variation on the circuit:
The fixed inductor might work out instead of a roller inductor . . .
When I tested the use of three components, I did so as a balanced pi circuit. I have a very good feeling that by changing the wiring and making a High Pass T for the Inverted U that I will be able to match all bands 160 – 30M, and using one fixed inductor
I should have the control wire run and the top wire replaced and the u.RAT tested by hand later today after work. I’ll test various components on the u.RAT board. I will go with one of several possibilities – and use clip leads to test a variant of a 2 component L – C circuit and then the 3 component High Pass T circuit – if I have trouble matching 160 – 30M (higher bands being a bonus).
Speaking of higher bands, are there any higher bands that would work using the Inverted U?
Well, sort of – 20 and 17M look great on the elevation angle, but their azimuthal patterns are pretty weird, not even worth thinking too much about.
Here’s my test plan:
- Try just one variable capacitor series feed (maybe inductor as well, but I fully expect a capacitor in series will match some bands – but not all)
- Try variations on the 2 component L – C
- Try the T with a fixed inductor
The u.RAT board will either end up driving one L and C or two C’s in the circuit. If I find that the fixed coil needs several taps to make this work, then I could use the one last spare wire in the control cable to add in a high powered relay and switch in maybe 2 different taps. I would change the KPOD code so that one of the function buttons changes the tap by applying power to the relay. It will have a default setting and a push of the button toggles 12v to that relay – it would mean one GPIO pin – so its really easy to do. I am very confident that one of these methods will work and work well. I can also look into the many relay driver boards that would allow a more exotic set of switchable taps – but I might exceed the number of wires needed in the control cable. I’m hoping I don’t have to go this route at all actually. Just having two steppers doing all the work would be what I really want – so I can get this thing on the air ASAP.
Posted on October 26, 2017
I added the ground to the Inverted U, and while the tuner liked it – in the shack with high power, the amplifier faulted. I know the tuner is the wrong tuner, and the values of L and C were both very low.
I don’t really know why, but I will experiment more using a different tuner. For tonight and tomorrow I’m back to the Inverted U.