KY6R Summer Project: Arduino Stepper Motor Driven Palstar BT-1500A!

K8AC’s wonderful balanced antenna tuner with stepper motors and controller

K8AC Control unit

One of the coolest projects you can do in ham radio is automate an “analog” or manual antenna tuner. I just bought the Palstar BT-1500A, which is a balanced tuner, and I fully expect that it will be great on 160 – 30M with the “Mod Bob” antenna that I wrote about in an earlier blog post. In fact, for 160, I can bypass the BT-1500A completely if I want, but that would require as much work to come up with a safe switching scheme than just using the tuner in line and probably having the L and C set to pretty much zero in both places.

WD4ED  also has a set of videos on his project that looks really close to what I would need. If all I could do is set memories for the stepper motor locations, then I’d be set. I’m not too concerned about making the control part fully automatic – just to make sure the remote stepper motors go to their right positions. The reason I don’t need it to be “perfectly” automated is because my SPE Expert 1.3K-FA just needs < 3:1 SWR, which would be easy to do with some memories that I could manually click on ion the shack on the PC. Maybe I’ll tie into the K3 band control line later.

Anyway, there are so many variations on this project with videos and circuits and other hams to contact and get some pointers from.

Last summer I started a project that ended up almost lasting a year – I feel like I took a real “trip around the universe” trying to find the best / lowest noise / highest RDF 160M receive antenna system, and that was a huge success.

This time I expect that this will be a bit more straight forward. What’s cool – I can mount the BT-1500A at the base of the antenna and use my AA-30 to first check to see if just manually I can get the antenna to be < 3:1 SWR on as many bands as I can from 160 – 30M, and maybe I will really luck out – but I expect that something will need to be tuned. Maybe it will be really easy and I can set the roller inductor in one position and then have one stepper motor on the capacitor.

Ed, WD4ED went this route and explains in his video that he went this route because he smoked one of the high power LC based remote tuners (like the MFJ), and his concern has been my concern because I have smoked a remote switch before. This is mainly because the voltage can be in the several KV range when tuning and when off the mark – and also you just don’t know exactly what a remote auto tuner is doing. When I used to use the Palstar AT2K in the shack with my ACOM 1500, I never had any doubt what was going on and that my rig and amp were being operated correctly. I avoided amp faults by being really careful.

The Mod Bob is a balanced fed antenna, so it requires this different kind of tuner – the BT-1500A.

I’m excited that I have such a cool project because on the air – conditions have just been poor, although I did hear W1AW on 160M last night better than its been for a while, and for the first time in several weeks heard a ZS on the long path on 40M this morning.

The “summer project” is a great way to compensate for crummy conditions. I used to assume summer is no good for the low bands, but last summer I proved that is not exactly true. However, having less daylight means it gets harder to DX on the lowbands and still get sleep!

Caveat: I have no lightning. That makes a huge difference.

I have a theory that we really are going to experience better low band conditions “just around the corner” because 160M is so long over due for an improvement. But as always, DX-ing takes a lot of patience – especially on 160M.

Guest Blogger – Mike Coffey, KJ4Z

The absolute BEST thing about working on VK0EK was making new friends and sharing in the success of the project. Mike is a forward thinker and the master mind behind the VK0LD Remote operation, and he also worked very hard behind the scenes – on the OQRS system, networking and the satellite gear, and many other critically important behind the scenes tasks and programs behind the VK0EK scene.

I’ve kept in touch with most of the team, and all of the “Diablo DX-ers” – the “back office” team, and Mike and I have a running dialog about DX-ing and Ham Radio.

Mike has graciously agreed to Author some blog posts on this blog, and I am very excited about this – thanks again Mike!

VK0EK Makes ARRL News Page

Perhaps the last of a long line of VK0EK News Blurbs, but with the cover of the October 2016 QST “DX Edition”, the Cover Plaque Award for that issue and article, DX Magazine and being on the cover of the DXCC Yearbook – this is the “final final”. (I think).

SPE Expert 1.3K-FA First Impressions

I wasn’t in the market for a new amplifier, but when looking at the new Elecraft KPA-1500 (and realizing the price would never get board approval), I looked at competing products and found this one. I read the reviews, looked at the price, and as soon as I sold my old car – I ordered one.

First of all – its a dream footprint wise and it has a very nice setup / config interface – its very intuitive and the manual got me started right away. With the cable Dan made, the amp tracks the K3 perfectly. Some things to note:

  • It does put out 1.5 KW no problem
  • The drive you need to give it is tiny – lower than what you have to give the Elecraft KPA-500 (and that as already low)
  • The tuner reminds me of the ACOM 1500 which is that it will match up to a 3:1 SWR, (the Elecraft KAT-500 range is much better). Luckily, my 40M phased array, home brewed 20M yagi and the “Mod Bob” on 160M are resonant on each of those bands – so I have three bands that do not require an outboard tuner – and the 1.3K covers each of the entire bands, which is great. When I run high power I try extra hard to offer a good SWR right at the antenna. I do need an out board tuner for 80 and 30M – and that’s what the Palstar BT-1500A is for – it will be mounted in a weatherproof box out back right at the antenna at some point – I will experiment with it this weekend. Maybe I will finally build that remote synchro or stepper motor drive for the BT1500A – make it Arduino based. That should almost be an “out of the box” project, but we shall see. It all depends on whether or not I also need to switch in the Hi and Lo Z portions of the BT1500A, or if all I need to do is tune the two front panel L and C control knobs. Anyway all of this was baked into my decision to go for the BT1500A, but I digress . . .

Bob and Dan at Expert Linears were the best to deal with and I highly recommend them. I loved my ACOM 1500, but I just found the next step up in my amplifier pursuit, and the price was right in my budget. I very much see why people have ranted and raved about this excellent Italian amplifier – and Expert Linears America, LLC (the US Distributor).

I do think it will make a difference on 160M and because the bands have been so lousy – I’m thinking more and more that full power will be needed for Bouvet . . .

I will keep the KPA-500 and KAT-500 as backup.


The KY6R “Favorite / Essential Gear” List

My all time favorite rig is the K3. I’ve owned my rig since 2008, so its by far the longest I’ve had one rig. Its what got me to Honor Roll and even after all these years its still seems like quite the performer. I also love my KX3 for portable work, and previously loved my Ten Tec Orion II, but I will keep the list to just one product in each category. I know a lot of people have moved to Flex gear, but I have no desire to.

SPE Expert 1.3K FA amplifier. The best amplifier deal out there and as many others have mentioned “a game changer”. I’ll be dedicating a full blog post to this shortly. I had no intention on buying another amplifier, and was seriously looking at the new Elecraft KPA-1500 (since I love my KPA-500 and won’t sell it any time soon). For a tube amplifier, the ACOM 1500 is by far my favorite tube amplifier and was sad to see it go, but the road to Top of Honor Roll and 160M DXCC is a long and winding one equipment wise. Selling my car funded this.

The N6BT DXU-32 and AB-577 Tower combo. Best high AND low band (TX-RX) antenna system ever – hard to believe I had the “audacity” to put it up – but glad I did. Twas great to experience being one of the first ones on the West Coast to get through several massive pileups to very rare entities. I have no regrets selling it and switching to a low band station, and love both my “Mod Bob” and phased vertical arrays, but I have to admit – I was a “semi-big-boy” for a couple of years.

Remote switches – DX Engineering. Their 8 position remote switch is one item that I was really impressed with – and this DVA-40-P is not only a fantastic 40M phased array – but turned out to be a great 160M RX array.

Wellbrook ALA1530LNP receive only antenna. I’m still blown away by its performance, and more than a little embarassed that its was the last RX only antenna that I tried.

Palstar antenna tuners – any of them. They are by far the best “analog” / manual tuners out there.

Best SWL receiver – Palstar R30CC – for SWL and BCB DXing. It “hears” everything my K3 does, and its audio quality is like a tube receiver – very warm. It is better for AM broadcast stations than the K3, but I’ll take the K3 for CW.

Astron RS-35M linear power supply.

K3ZN – for my “touch”, Tony’s keys are my all time favorites.

I love my Koss Pro4S headphones – they are so well built (aluminum), are light, very comfortable, and sound the best for CW, SSB and even AM broadcast. Very clear, non fatiguing.

My favorite microphone, even though I am on CW twice as much as I am on SSB, SSB is still important in my DXCC goals. There are several ATNO’s that I have that were SSB only.

I did not use a rotator on the N6BT DXU-32 but used the AB-577 “spanner wrench” Armstrong style. I was much more comfortable with this because unless you buy a very expensive rotator, I just don’t trust the lighter duty ones. Because I usually park the yagi in the direction of a DXpedition, I say the heck with them and that they are just a failure point ready to happen. I don’t have one on my KY6R two element 20M home brewed yagi.

I have gotten my money’s worth out of this antenna analyzer 100 times over – its a wonderful piece of gear, and is really great with the Ant software.

The Fluke 115 is used all the time at Chez KY6R







Bouvet Watch: Comparative Solar Condition Analysis

May, 2017’s average sunspot number was 18.8, which is about what it was like for VK0EK. In fact, the average for this year is somewhere close to this. This snapshot is from the web site, and it differs from the NOAA website:

The difference is not the “actual”, but the Predicted. In both cases, the real average has consistently under performed the predicted. What has been most interesting to me is that had updated their prediction to include that “knee” – and it is as optimistic as you can get for where we are in this cycle. We truly are flirting with the bottom of the cycle. The top of that little “uplift” will be this coming October – only 4 months away, and while that’s the “last gasp” of somewhat “OK” solar conditions – things will still be OK in January, when 3Y0Z is on the air. In fact, September and the Autumnal Equinox is only 3 months away – I must be really busy at work – time is almost going too fast these days! I mean – we are scraping the bottom of the barrel here – but for such an under performing cycle – its as good as it gets. I expect some very good conditions this Fall and Winter – but they will be short and sweet. This does bode well for Bouvet!

It does seem quite ironic that there is that “knee” and even an uptick that might occur in October, 2017 and that conditions will still be “elevated” from what NOAA predicts through January, 2018 – and then we will most definitely quickly drop to the bottom.

Lets compare what they predict for the Bouvet DX-pedition and what I worked at the same time in the last cycle with very similar conditions. Conditions in September 2007 were the same as they are now:

3B7 is pretty close to Tromelin

3B7C – Agalega and St. Brandon. This one is the best clue as to what to expect because it is much farther away than 3Y, and I know for a fact that I worked them Long Path. In fact, for one QSO, I was in a minivan parked with a 102″ whip, IC-706MKIIG and an AH-4 tuner over the end of the Prosser Creek Reservoir just north of Truckee, CA. And I worked them on 40M this way! Its was the most amazing thing – their signal at sunrise was simply amazing and I never ever expected to work them this way. I remember that Winter was not far away in the Sierras at that time – it took some hot coffee to keep me warm.

I worked them on the Long Path on 80, 40 and 20M, and Short Path on 30M. I remember their operators and signals were just the best of the best – The 5 Star DX Group – who are the world record holders for most QSO’s with their T32C DX-pedition.

Here is the most hopeful news. I worked these other entities for ATNO’s:

  • BS7H – Scarborough
  • D60VB – Vlad in Comoros
  • VU7RG  – Lakshwadweep
  • 3B9/G3TXF – Nigel on Rodrigues
  • VP8LP – very surprisingly on 12M

Besides VP8LP, all were 20M or lower, except Vlad on Comoros – which was 17M. That opening to Vlad was very short – maybe 10 minutes. VU7 was open for about 1/2 hour – but very workable for about 20 minutes only. All of this is good DX, and quite rare – proving that you just never know when you will get those breaks. I also know that in 2010 I had a few like this – and the conditions were also this “bad”.

Comoros, St. Brandon, Rodrigues and Lakshwadweep are actually not entities that I would ever expect to work given “the numbers”, but there almost seems to be some “antipodal magic” going on here. Lets see what Father John – ON4UN says in his “good book”:

Sure enough – on pages 1-34 and 1-35, John discusses “Antipodal Focusing” and Signal Ducting, and I am sure that this must have been the case for me in that mini van. Its one of a handful of QSO’s that I will never forget.

Here are my recommendation(s)

  1. Make sure you are there for what will be pretty short openings
  2. Make sure you have good Low Band antennas, but 20, 17 and 15M might also be good. The lions share of the QSO’s will be 40 – 20M – I am SURE of this
  3. I do think having full power will be needed as well – although the team is very good about working out the band and giving everyone a chance. I have a story about my power situation – in a blog that I will post later this week. One reader will give me hell I am sure!



Palstar BT-1500A: Feedpoint Impedance Education in a Box!


I’m very pleased that my “Mod-Bob” antenna ended up being one that used “tuned feeders”. Well – therein lies the rub. I don’t really, really understand this antenna – because it seems to look like three phased verticals like a Bobtail Curtain – but does so on 30M as far as EZNec is concerned. But the feed is not at all a classic Bobtail feed – because I am not feeding against ground radials – which would be a voltage feed. Instead, my feed looks more like a dipole current feed.

Here are some simple, yet very easy to understand references to look at for a 1/2 wl dipole feed:

and a 1/4 wl vertical feed:


I’ve heard conflicting opinions regarding the efficiency of an “L” tuner circuit vs. the more common “T” circuit, but the Palstar BT-1500A is designed for open line feeds to the antenna. It has several switches and settings to allow for high and low impedance matching – and seems like I will be able to learn a lot from this antenna and project. The manual is very good – its an education in itself, but with my very trusty and well used Rig Experts AA-30 antenna analyzer and “field laptop” (an old Dell “beater” laptop that can go out in the yard with me), I will be able to try different settings on the tuner and measure what happens with the AA-30. I’ll learn right away if I need to run a 12v line out to this remotely installed tuner – or if its “default” switched circuits are good on all low bands.


I do know that the antenna is 50 ohms on 160M. What is interested is each “side” of the feed is 117 feet long. This is almost 1/2 wl on 160M – which is pretty cool for a 160M antenna that fits in a small suburban back yard. So, for starters, the impedance is LOW on 160M.

I know for a facty that on other bands the impedance will swing high – I suspect that on 80M it is especially – because the KAT-500 does not like the SWR much at all and I’m restricted to 200 watts or so there. Otherwise – on 160, 40 and 30M its fine.

The AA-30 will give the full story – and then, by switching in combinations at the antenna where the BT-1500A will be mounted – I can really get down to business and document this antenna from a feed point perspective.

The actual measurements plus EZnec plots will be useful – I like “data visualization” because its a way to take a complex set of variables and produce something a non EE person like myself can understand.

I build data warehouses for a living, and love to get to the “art of understanding” with “visualized data”.