Posted on June 24, 2017
I’ve completed the first step of the project – to get the weatherproof BUD Industries box on the center element support of the Mod Bob antenna. You can see the coax and control cable sticking up out of the underground PVC pipe. The two Stepper motors will be mounted on an aluminum rail that lines the motors up with the shafts and they will have the proper shaft couplers. The clearance at the top of the box is perfect for the motors and the Raspberry Pi board and whatever driver board I use.
I also have a little control box left over from another project that is perfect to supply power to the BT1500A and also whatever processor I use out at the tuner.
I also received my Raspberry Pi processor – that has WiFI and Bluetooth on board. I’m starting to think I might go the Raspberry Pi route – but not sure yet. Raspberry Pi supports Python, and I would love to use Python. I also received the two stepper motors and the mounting brackets.
Raspberry Pi Stepper Motor wiring. I will need both 12 and 5V going out to the tuner. There are $15 dual voltage supplies that have the right current for the Stepper motors, so that will be easy to do.
It started getting hot – so I will wait until the shade hits that spot later today and at least pound the ground rod in, and maybe even hook everything up. If I don’t do it today, I will first thing in the morning tomorrow.
Posted on June 23, 2017
The support in the Maker world is just fantastic, with a spirit and camaraderie (that at least) rivals the ham radio community. The sharing and sense of wonder is very refreshing to me. Also the diversity is refreshing too. Ham Radio (and especially DX-ing) I hope gets joined at the hip with the Maker Crowd. I did see signs of this at Dayton, and the ARRL is doing yeomans work in this regard – Bravo ARRL!
I found this really cool idea by Giorgio Campiotti on YouTube. I can’t find his call sign, but I love the idea to use actual physical controls in the shack for the L and C and with wireless, set the BT1500A settings manually, but remote.
Luckily, with my test last weekend, I found that the BT1500A could use the same switch settings and only the L and C controls need to be tuned. This means the only control cable I would need would be to power 12v to the Palstar tuner (to engage the right relay) and also a 5v line for the Arduino that would be out back. Here’s my idea:
But I could even get away with something this simple:
Video by Adafruit – a company run by “Lady Ada” – AC2SN
Lets take this one step further – maybe use my Android phone as a remote control?
What is especially cool is that the “Makers” are into radio controlled cars that use servo or stepper motors, so basically, its all Open Source, and I doubt I will even need to do more than plug stuff in and download code. In fact, because the remote car needs steering, that’s a lot more complex code wise than what I need. But that’s fine – I could take a remote car program and chop out anything except for the servo or stepper motor control.
I even had another weird idea:
Basically, start designing and building a ham radio control and command platform – that uses the Raspberry Pi to control Arduino based remote devices – like my antenna tuner and also a wireless remote antenna switch.
Here’s the answer to these questions:
- Is ham radio still relevant?
- Is DXCC still relevant?
- Can we get new, fresh blood to join the ham radio ranks?
The answer is YES. Sure, the EMCOM crowd sure seems to be very healthy, but what about building stuff and DX-ing (which are my interests). Well, Ham + Maker is THE answer!
Posted on June 22, 2017
I’m going to get the Palstar BT1500A out at the base of the Mod Bob on Saturday morning, and will then spend some time playing with both an Arduino board with a Stepper Motor driver shield. I will also get a Raspberry Pi 3 running – and I am really interested in the Raspberry Pi 3 because of its built in WiFI and Blue Tooth.
Except for a few odd QSO’s here and there, I swear, my DX-ing days are really limited any more. I feel like I’m done with DXCC – there just isn’t much left to do that interests me. Honor Roll and DX-pedition of the Year seem to really feel like I have done it all.
The good news is I have been enjoying coding Python at work almost like its my new hobby. Luckily, I have a fever that only making something will be the “More Cowbell” for my soul.
Ham Radio hardware, Maker hardware and software – what a great combo!
Posted on June 21, 2017
The best 160M receive antenna was a total accident. I had my DX Engineering DV-40-P switched in the “Both” or 180 degree position and heard the weak signal DX with -130 dB noise. That’s 10 dB less noise than my second place RX antenna, and 20 dB less noise than my third place RX antenna. It also seems less prone to QSB than the other antennas. The signal seems to stay above the noise – even when there is fading. I was able to build ONE antenna last summer that matched this – it was a K6SE Flag, but instead of feeding it on one side with a resistor at the other end – I ran coax to both ends and brought those into a DX Engineering NCC-1 (or NCC-2).
My second place RX antenna is the Wellbrook ALA1530LNP Loop. As I said, its 10 dB noisier than the DXE DV-40-P, but when put in Diversity Receive and used as a second RX port antenna – with the DV-40-P, now we have a little more noise, but less QSB – when one antenna is affected by the QSB, the other picks up the slack. Its a great sound in my headphones, by the way!
Third place is the “Mod Bob”. It is much better than the old Cushcraft MA160V on receive, but is still below the other two RX antennas. HOWEVER, when fed against the Wellbrook ALA1530LNP, some real “magic” happens. The two together are only 10 dB noisier than just the DV-40-P, so like the Wellbrook alone, but the signal now is much better than the DV-40-P.
Here is a list of all of the antennas that I tried in the past year:
- Home brewed RX loop a la ARRL Antenna Handbook and with a W8JI improved feed. In fact, I tried phasing these through the DXE NCC-1 and NCC-2. Just OK – not worth it. I even built tuned circuits at the feed – and that just made them noisier. I also tried adding W7IUV preamps – same noise issue
- Flag and pennant – pretty weak and very noisy (I’m sure its my QTH and my neighbors houses)
- RBOG – showed some promise but pales in comparison to what I have now
- Phased 20′ hatted verticals with tuned circuits – phased through NCC-1 and NCC-2. Similar to the EWE fed with two “vertical dipole” like feeds, but the “dual fed EWE” was a much easier antenna to put up – two fiberglass masts and wire
- 60′ top loaded vertical – noisy
- MA160V – noisy
The most critical hint and tip is to get your RX antenna as far away from ANY house or building that has electrical wiring in it. The WORST you can do is put a RX up on top of your roof – where every heating duct, rain gutter and electrical wire can trash it with noise. Computer monitors, cable modems and routers, wall warts and dimmer switches (even in their “off” position) will make you hate 160M. Steer clear!
The Elecraft P3 is my best tool to measure noise and “SNR”. Read up on SNR – at W8JI’s wonderful site.
My year long “Top Band RX Antenna Challenge” are now complete, and as I start hearing the LU’s call CQ DX on 160M (their winter), it brings back fond memories of last summer, when I worked 5 new ones on Top Band, pretty much to my amazement (and delight)!
I put a ton of work in testing just about every possibility of RX antenna in my back yard – and now I have that all “dialed in”.
Next up is my Mod Bob remote tuner project – and THIS is why I love ham radio (way) more than awards chasing!, and believe me I have had a blast chasing awards – but that has run its course. These projects are picking up where the award chasing is leaving off.
Posted on June 20, 2017
An art piece I made years ago – but that still depicts how I feel about the (northern hemisphere) summer solstice. This week – until this coming Sunday is the “week of the longest days of the year”, and starting Sunday, we start losing daylight minutes. This is of course what low banders like – each day another day towards more darkness and longer hours for low band DX-ing . . . Of course, since its Winter Solstice in the southern hemisphere, the astute low band DX-er keeps watch on all low bands even in the northern hemisphere summer!
I worked late last night and rode my bike back from BART in Orinda at about 8 PM. Its always interesting to mark time by my bike ride – not too many months ago it would have been dark at 8 PM. I’ve been so busy at work since I started at Credit Karma that the seasons are rushing by. Right before I started at CK, I re-landscaped my front yard, and now that all of the plants are in full bloom, and that all weeds have been pulled and I only need to keep the watering up – my front yard feels like an extension of my living room. Combine that with my back deck overlooking the creek – and its a nice summer. Sure – we get the occasional heat wave, but I am more than thankful for our moderating fog that creeps in through the Caldecott “gap” nearby.
This summer has turned out to be “The Summer of Python” and also “The Summer of the Credit Karma Data Dictionary”. In the first quarter at CK, I have written 6 Python programs and designed a fully functioning and very utilitarian Data Dictionary. A Data Dictionary is a database of “meta data” or data that describes all of your data assets and elements. This is especially useful for say someone wanted to understand what data is available for reporting, but in today’s world – where applications and systems are “distributed” and “decoupled”, ensuring that two development teams working on parts of a large system or set of applications understand where the “single source of truth” is. Examples would be a companies customer list – or maybe a geographical lookup table. These types of data are sometimes replicated and get out of sync because one development team doesn’t know another team has already solved this problem. In today’s world – a software package like Salesforce or Netsuite – should be the “System of Record” (SOR) for some information, and in some cases the application code you write in house is the SOR. Having redundant efforts and sets of the same data that get out of sync causes all kinds of problems. This gets compounded when you have different types of databases designed by different teams. Its easy to create “impedance mismatches”.
I coded like crazy this Second Quarter – and now in the Third Quarter – I need to sell it internally by giving in house presentations and attending meetings. Its a very interesting job and pretty much my all time favorite company to work for.
Anyway, the Python you see above is Python on Raspberry Pi – which is something I am very interested in. I have been coding Python because it has turned out to be the most productive development environment (PyCharm) with a very powerful and simple language. I have never delivered so much in a short amount of time.
I also know C and C# and Microsoft Visual Studio – which is what you use on Arduino, so one of the many things I need to research for my stepper driven auto tuner project is whether I want Arduino and C or Raspberry Pi and Python or C.
Anyway, while summer isn’t the best for the low bands, its a great time for coding – (especially when there is a heat wave). Otherwise – goofing around with antenna projects in the back yard on a nice day is always big fun – and with no rain to worry about until perhaps November. I get my exercise every day going to and from work, so weekends are always open for hobbies or puttering around the house – which is how I love to spend my weekends.
Posted on June 20, 2017
The Mod Bob antenna on 160 – 30M ends up looking like a single vertical on 160 and 80M and on 30M it models just like a Bobtail Curtain. It does look like a dipole on 40M, but my 2 element 40M phased array almost always beats it, so the Mod Bob is used on 160, where it is resonant, 80M, where it is a poor match of 20:1 and 30M where it is about 6:1. My guess (and I haven’t tried this) is that a 6:1 balun would work on 30M – but then mess up 160M, and that 80M will always be a tough match.
I read this article by antenna guru Richard Measures, AG6K:
And decided to try the Palstar BT1500A, which seems to be designed exactly with AG6K in mind. That link is an updated version of the February 1990 QST article.
You’ll see that Palstar did a very nice job staying faithful to that design, and since I had never tried such an antenna tuner, this time it just seemed to fit. You’ll see in an earlier blog post that the BT1500A worked out in a test exactly as I had hoped – that one switch combination would result in just having to tune the L and C constrols – because then it would make it much easier to build a stepper motor controlled remote tuner with less $100 in “maker” style parts. In fact, with just a rotator control line, I can supply the Arduino and stepper motors with 5V and the BT1500A with the 12V it needs. In fact, here’s a way to do that:
And here is are the specs of a few options – both are less than $20:
There’s enough power for all components in the remote box, and with the 8 wire heavy duty rotator control wire, it should be just fine. I could even put the power supply just a few feet away from the antenna feed in the basement, but that’s not really necessary.
VU2ESE also has the same idea that I do – but he is using low power:
With 100 watts or less you can get away with a lot and never know how efficient and antenna system is. K9YC likes to talk about “commiting unnatural acts” when trying to use a Hi Z ladder line fed doublet as a multi band antenna. He says that the ladder line – because it can’t be choked can pick up noise and also become part of the radiator. In my case – its hard to say if this is a good or bad thing.
More than anything, the Mod Bob – being resonant on 160M is esily what matters. In fact, if 80 and 30M don’t work out or cause 160M to be less efficient using this feed scheme – I’d drop the BT1500A at the antenna feed point. But I have to try this.
The next test though will have to be with high power on 160, 80 and 30M and see if there are any issues at 1500 watts. I will have to set the SPE Expert 1.3K FA to bypass its own internal tuner for these bands. I will still use the internal tuner on my 40 and 20M resonant antennas.
W8JI has an opinion and has looked into the balanced vs. unbalanced tuner and baluns at the input and output of tuners:
Tom argues that maybe my old Palstar AT2K in the shack with a 1:1 current choke at the antenna might not be any worse than putting the BT1500A at the antenna.
This weekend – with full power and the tuner mounted at the antenna I will find out. I expect that maybe Tom, W8JI is right – because when I had the Palstar AT2K in the shack with the ACOM 1500, it never arc’ed or caused any issues.
The coax feed from the shack to the Mod Bob does go through the Array Solutions Rat Pack remote switch, so maybe moving the tuner out to the antenna will be better in that regard – I’m really not sure. The length is only about 60′, so I doubt that losses are a big deal with the tuner in the shack or at the antenna. Not really sure though. Not sure exactly what happens along that feedline – as I sure hope the heavy duty 1:1 current choke does its thing – which I am confident that it does.
I look forward to my high power test this weekend – the big test will be to see if there are any issues on the three bands with high power. The only downside with the SPE amplifier is that it is much more “finicky” than the ACOM 1500 tube amp in respect to SWR. But this might be a really good thing – because it is forcing me to test and try this different approach.
I do know that coax fed dipoles on every band is a great way to go – but on the low bands this is simply not possible. I also know that my radial field for an all band (or all low band) vertical ends up being hatted and causes serious voltage issues on components at the base of that antenna – I have fried a switch that I used to switch in different L and C components in an unbalanced scheme.
I am avoiding the loss of my radial field with the Mod Bob, and sure hope that I have no issues on 160, 80 and 30M with this weekends test.
I hope it proves that this was a good way to go – we shall see.
Posted on June 20, 2017
I’ve got a BUD weatherproof gasketed NEMA box that is perfect to house the Palstar BT1500A. This weekend I will put it out at the antenna and hook up the 12V supply line. I have an old switch box that I can use for now – and I might put a coax “tee” at the input so I can go out and plug in my AA-30 re tune it manually for whatever band I will be on with the Mod Bob antenna.
In the mean time I will be receiving 2 NEMA 23 stepper motors, drivers and possibly an Arduino DUE, which was recommended over the Arduino UNO that I have. I will also use the 8 conductor rotator line that is already set up to power the BT1500A and the Arduino – but will try to use wireless to control the actual steppers via the Arduino board. I am thinking I’d like to just use two optical encoders in the shack and I can just watch the SWR meter on the Expert 1.3K FA and K3 while tuning – just as if the tuner were in the shack.
I can’t get on 80 or 30M right now until I get at least the manual set up working. I know from writing code – that its always a good idea to run it manually as if you are in production while QA-ing – you always find operational quirks that you never ctch when in your development environment. Luckily there is absolutely nothing going on for me to chase – so I just play on 160, 40 and 20 with my resonant antennas. With the activity level and conditions as they are – I’m not missing a thing.
So – this weekend will be the time to do it – this past weekend was over 100 degrees out – so its was an indoor / air conditioned weekend for me. Luckily we then get our fog back in – and I saw it starting to build in San Francisco, so this means I should have a nice weekend ahead for the very start of this project.
I’m not in a big hurry – I want to play around with the Arduino stuff in the shack and also get my ideas well formed before I commit and “go live”. I have all summer to play with this stuff – which is tres coolio.