Posted on April 2, 2018
I’m surprised that I hear LA1MFA so well at this time of year, but I guess the vernal equinox conditions are still there. Over this month this path will go away most likely – but since we are getting close to the beginning of solar minimum, it will be interesting to see the affect on the low bands – especially 40M, but also 30 and 80M. I also hear an OK and just worked an HA station easily with 100 watts and the DV-40P. I could also hear them almost as well on the UrbanBeam.
Now that I think about it, 40M to EU will actually give way to a late afternoon / early evening SP opening to EU and in good sunspot times the Middle East and Africa. This path does not open much during the solar minimum, so the test is whether the West Coast can hear 9K2GS nightly on 20M.
We shall soon find out.
Posted on March 31, 2018
That was fun and much simpler than trying to create a multiband matching circuit.
I ended up using refrigerator tubing for the coil. It’s about 4″ in diameter, and 9 turns. The direct line was good for 3.857.5, and the coil let’s me go down to 3.515.
I also have a 1:1 current choke at the input, which means the common mode current will not travel on the feedline, and I shouldn’t see any more amp faults on 80M as I have in the past.
Its been several weeks worth of testing and experimenting, but I am very pleased with the outcome. On a small lot – if you have a good single mono pole solution for the low bands – with a great radial field and a full 1/4 wl up, you will have a great DX Antenna.
Besides 80M, I found that this antenna is excellent on 30M.
Posted on March 31, 2018
It’s been one of those bizarre weeks at work, but ended with a big award for designing and implementing two things – a Distributed Data Dictionary that inventories and catalogs database objects across all MySQL, PostgreSQL and Bigquery databases, and a system called Universal Customer Reporting, which provides data to Data Scientists in a way that is modular, meaning re-usable, scalable and flexible. The problem with Big Data data stores is that they become junk yards of experiments and disorganized wastes of huge amounts of data. Not “Data Lakes” – but “Data Junkyards”.
The week started with some frustration but ended on as good a note as I could have hoped for.
Posted on March 31, 2018
Posted on March 30, 2018
After reading Tom, W8JI’s page on Linear Loading vs. Coil loading:
He says this – “Linear Loading is really nothing other than a poor form-factor inductor. The radiation from the linear loading does NOT change the radiation resistance of the antenna except as the effective position of the load might change from the direction of fold. In all cases, a proper form-factor inductor would have less loss, and provide the same radiation resistance.”
I just happen to have a very high quality, High Q coil that looks like this:
I also found a nice web site that shows how to build your own coil. I also have a big coil I built a while back from refrigerator copper hose, so that would have the highest Q:
I will first just take some clip leads and see if I can find a set of taps on the big coil I have for 80M. It will make the box a lot simpler too:
Its an elegant solution – I’m going with it . . .
Posted on March 30, 2018
The Elecraft KAT-500 can handle pretty high SWR for most of the ham bands, but I noticed that on 80M especially, and when the power is higher than about 300 watts, things get a little “touchy”. With the KPA-500 in line, I have had a constant battle of amp faults – and I have tried all kinds of antenna matching circuits – in the shack and at the base of the antenna. I think the real issue was – I was trying to use the antenna in the 80M CW band and also at 3.857.5 for The Mission Trail Net. If I only could choose one, I would take 80M, and since at 1.8:1 or less (I don’t like higher SWR because of the amp situation), I’d just cut the antenna for 3.15 mhz and be done with it. In fact, right now, I could just shorten the antenna by at most a foot and I’d be done. At 100 watts up at 3.857.5, the KAT-500 is fine, and the net notices how much better this 60′ antenna is over the old Inverted L where I had to switch in an LC circuit so it could work on 160M and 80M. In fact, on 160M – the “real” was ALWAYS CW for me – SSB was a non starter. Something to think about.
The antenna as it is right now – is resonant in the 80, 30, 17 and 12M bands. This really is a great thing, especially because I am getting 30M out of this deal. A while back, Tom, N6BT told me that my radial field is good with a vertical when the bandwidth is narrow – that a wide bandwidth means there is a problem with the radial field. So – the antenna and radial field are good – I just need to “behave” in my use of it.
I need to do some serious A – B testing between the UrbanBeam and this 60′ vertical on 30M – that will be fun. There is always some kind of fun little antenna experiment going on here at KY6R! I guess its true – its always been about the antenna – WAY more than DXCC – although DXCC is a great “leveler” – a thing to give you structure and drive – a goal and a purpose to guide one through this antenna “adventure”. An Antenna-Spedition? Antenna-Palooza?
I started building the switchable 80 / 75M circuit, but I’m wondering if I had a direct and a linear loaded loop at the base if the RF would follow one or the other path depending on frequency that I am on. I bet the answer is no – that it will always find the shortest path – which would be 75M. The difference in wire length is several feet – up to 7 in fact.
I checked with Bob at Balun Designs and he recommends his 1:1 Current Choke (I have one) plus my idea to switch in different stubs. He thinks my amp faults are due to common mode at high power.
That makes total sense.
Posted on March 29, 2018
I’m in for a good whuppin’ from the Peanut Gallery, but here is where I am at now. One Wellbrook ALA1530LNP has been up a year, the second added this past winter, and when phased using the DX Engineering NCC-2 finally gives me what I had hoped for when I started trying to come up with a great Top Band RX antenna. Luckily, with the SDRPlay RSP2Pro, this antenna system ends up living on and is a ton of fun. When I get bored of the ham bands, I can listen on bands from DC to Daylight, so there is always something fun to do. One weird thing I do is try to listen to smaller, more local AM radio stations since these phased loops let me hear and filter out small stations that are on the same frequency as a much more powerful station. Its really amazing.
The DV-40-P 40M phased array lets me check in with ZS stations every night, which I never get tired of. I also like the morning LP grey line to ZS as well. This antenna wins the longevity award – its been up 2 years now.
The two biggest surprises – the SteppIR UrbanBeam – on the US Towers ALM-31 – has me now back in the DX Chase filling in my “DX bingo card” – and adding DXCC Band Mode slots – just having 40 – 6M at the push of a button and a rotation of the rotator – I’m surprised at the effect this has had on me – since I swore off DXCC. I won’t chase any more awards – but the LOTW credits ARE the award for me. Funny how I value data in a database much more than a plaque on the wall these days – but hey – I’ll take it! No – its no N6BT DXU-32, but its much safer and covers many more bands. I am going to try to add some 6M slots – since I now have 3 elements on that band that is actually up high enough to be a really good DX antenna.Wow – I need to look for those 6M “enthusiast” sites. That’s another big surprise – I swore off 6M in the past.
The biggest surprise is how I felt compelled to “cash in my Top Band chips” and switch to a 60′ 80M vertical. I can say with full confidence that a full sized quarter wave vertical – with a great radial field is a superb antenna. Forget about that malarky about verticals being bad radiators in all directions. 80M is the last band where you can put up a really tall vertical on a tiny lot and be a DX force. 160M is barely practical on a small lot – but 80M is a world of difference as far as that goes. I do like this 60′ 80M vertical much more than all of those compromises I had to make on 160M. Sure, two phased 80M verticals was “a bridge too far”, but I am very happy that I at least tried it. Even without the ability to A – B test, I know that this 60′ vertical on 80M is significantly better than my previous Inverted L. Not to mention – when you multi band an Inverted L – it becomes a big compromise on 80M. It was “good enough” on 160M and did get the job done – but getting rid of that horizontal component and going “straight up” is noticeably better.
Here is an interest fact – even the tallest Spiderbeam fiberglass mast (85′) is way too short on 160M, but with a very little base linear loading – their 60′ mast if a great 80M vertical support (don’t try using one of these as top loaded support – the tip is solid and very flexible – you can’t use the tip to hold anything more than a wire taped to it as I have.