Ground radial patterns for vertical antennas

I don’t have a small lot, for a suburban home. It is about an acre. However, my house sits almost directly in the center which makes placement of antennas slightly challenging. I have a very enjoyable 50ft tower about 20ft off the end of the house with a triband yagi and an inverted-V doublet hanging from a crossbar just below the top. This gives me 10m-80m coverage with two antennas. But the question looms: what about 160m?

I know I won’t be able to put up a full 1/4 wave 160m vertical (120+ feet). So my designs revolve around an inverted-L. I have a small landscaped island in the back yard about 20ft from the tower where I can install a base for an inverted-L, and use a PVC elbow joint on a support cord from the tower for the bend in the L. A tree at the other end of the yard can support the top end of the L with a pulley and weight to accommodate the wind. But, the problem then remains with the radials.

For any vertical the minimum recommended length of the radials is 1/10 wavelength. For 160m that ranges from 49.2ft to 54.67ft. Most people recommend 50ft so I’ll use that for sake of argument. From the proposed vertical base, I can easily do 50ft in two cardinal directions. The other two are limited to maybe 30ft. That’s not enough. And thus brings me to the “ah ha” moment I had while researching this:

This is brazen taken from this post by WB5YUZ over on QRZ:

You do know that the radials can be formed into a spiral or any other pattern, as long as they don’t overlap, right? There is a TIS I know of that uses a very short (in terms of wavelength) vertical and less than ten watts to transmit on the AM band. The FCC intended this type of station to be audible up and down a few miles of roadway, but this station can be heard twenty miles away, even after dark! (Obviously this means they are exceeding allowable field strength limits, but I bear them no ill-will, so I don’t want to identify the station.) I asked the station engineer why he thought the set-up worked so well and he said, “I use 120 full size 1/4 wave radials.” I asked him how he found the space to fit them all, and he said, “I laid them out in a spiral pattern.”

Just. Brilliant. In hindsight, it is also obvious.

I need to see how this will work in my yard.

Posted in Antennas

WN8U Logger 1.4.0.0 Released

I finally, finally got the latest revision of the WN8U Logger released. This has been a long time coming. A lot of the code complexity has been cleaned up and I now have excellent support for the Winkey, KX3 CW/PSK/RTTY internal keyers, and even the KX3 digital voice recorder. The K3 should work on the KX3 settings, though I will add explicit support for the K3 soon. The Kenwood TS-590 is high on my list as well for CW and digital voice.

Right now the only contest module I have available is the Ohio State Parks On the Air 2016. That’s because it’s coming up in three weeks. I may release the Ohio QSO Party 2016 module in the next week. Maybe.

The biggest improvement is that the rest of the contest modules will be much easier to write and maintain going forward. Look for more updates soon!

Posted in Uncategorized

First NPOTA Activation

This past weekend I did my first NPOTA activation. I was at the Hopewell Culture National Historical Park in Chillicothe, Ohio. I had texted my friend Denny (KC8RPV) to find me a nice quiet frequency on 40m while I got setup. When everything was ready, I called and he replied. He had used the local repeater to line up a few others to work me, and he spotted me on the DX cluster. After my third contact the pile-up started and never let up. I ran that frequency for 70 minutes, with a 6 minute break and wound up with 121 contacts. Not too shabby!

My equipment was a KX3 with a KXPA100 amplifier, a Plantronics headset for hands-free VOX operation, a laptop with N3FJP for logging, and my vehicle for power. I had run power lines from the battery terminals through the firewall and into the cab. I left the car running to have a higher voltage (alternator voltage was 14.3v versus the battery voltage of 12.2v). The antenna was a 35ft wire soldered to the center of a PL-259, taped to the side of a 40ft fiberglass mast from Spiderbeam. The shield of the PL-259 had a wire soldered and I attached that to a jumper connected to the frame of my car for a counterpoise. The mast was supported by zip-ties attached to the wheel of my car. It beat lugging around some sort of drive-on support!

Now for the embarrassing part… I had left my coax at home. So what I did was place my amp on the hood of my car, plug my 1:1 balun (unun?) into the amp and plug the antenna straight into the balun. It was very efficient, I had zero feed line losses, because I had no feedline! But seriously, the antenna proved to be excellent. Signal reports were good from everyone who worked me and I worked at least twenty different states plus Ontario.  It was a tight fit getting the connections from the amp to the KX3 into the operating position (driver’s seat) but it just barely made it. It had a very good time. Setup was about ten minutes and teardown was even less!

I was flying high after the activation all day, and the next (Monday). I decided then that I was going to activate as many NPS units as I can in 2016.

Pictures from all of the activations will be hosted on Google Photos: https://goo.gl/photos/MCc9RHeKNSgQpys6A

Posted in NPOTA

Field Day and Field Day Planning

Something to consider as we all gear up for Field Day tomorrow. Some clubs (like mine) have done extensive planning. Well, plans are good but don’t forget these snippets of wisdom as you deploy to the field.

“No Battle Plan Survives Contact With the Enemy”

To quote German military strategist Helmuth von Moltke,  “No battle plan,” he sagely noted, “survives contact with the enemy.”

When your plan meets the real world, the real world wins. Nothing goes as planned. Errors pile up. Mistaken suppositions come back to bite you. The most brilliant plan loses touch with reality.

Or as Robert Burns put it, “The best-laid plans of mice and men go of awry” — but he was only partly right. They don’t often go awry… they invariably do. This all leads us to Planning Error #1.

Planning Error #1: Relying on Plans Leads to Failure.

Note that I did not say “plans lead to failure.” However, the reliance on plans — especially on the congruence between plan and reality — after a project begins is usually an exercise in self-delusion.

When plans meet the real world, it’s not the real world that will yield to your plan; you much adapt whatever you’re doing to the circumstances truly at hand.

Consider the hobby of racing sailboats. There is a racers’ expression, “Get you head out of the boat.” In other words, while it’s good to gather data from your instruments (wind speed, boat speed, compass direction, etc.), all of that matters only in relation to whatever else is happening on the race course — other boats, areas of lighter or heavier wind, and so on.

Being caught up in your plans is like being caught up in your instruments. They provide local information, but they do so without context.

So… if plans fail, is the time spent making those plans wasted?

“Plans Are Useless, But Planning Is Indispensable” – General Dwight David Eisenhower

One of the greatest planners in history was the guy who laid out — and got right — the incredibly complex Operation Overlord, better known as the D-Day landings during World War II. Consider Planning Error #2 in light of Planning Error #1:

Planning Error #2: Lack of planning leads to failure.

Most project managers will state loudly their agreement with this thesis… yet in the press of action, it’s amazing how many jump right to execution, either skipping planning entirely or paying it mere lip service. In fact, project managers have a phrase that encapsulates this problem. “Ready, fire, aim” is PM-speak for the failure to plan.

Sometimes, you must act before you plan. In an emergency, often you must respond immediately, in a project as well as in life. If you’ve planned for that emergency, of course, your response is likely to be easier to muster, but not even the best planning covers every contingency. However, not everything in a project is an emergency… and with a good project manager, even true emergencies won’t feel out of control to the rest of the team.

Even in emergencies, try to limit “unplanned” action to whatever is needed to stabilize the situation. Don’t let the need to act quickly on one step spread to acting-without-planning on all steps.

True emergencies are not the norm, however, although unprepared project managers can make everything seem like an emergency. As Eisenhower says, you need to get serious about planning… though remember von Moltke’s dictum about not getting locked into plans.

Posted in Portable

Antenna Gain: dBi vs dBd

I’m just going to post this once, and then point anyone here that needs a ‘refesher’. I see too many incidents where people quote gain in an antenna and really don’t know what they’re saying.

 

Antenna gain is measured in either dBi or dBd.
It is important to note that antenna gain is different than amplifier gain. Antennas do not have a power source that allows the antenna to create additional energy to boost the signal. An antenna is similar to a reflective lens in principle – it takes the energy available from the source and focuses it over a wider or narrower area. Antenna gain is then a measure of the amount of focus that an antenna can apply to the incoming signal relative to one of two reference dispersion patterns.
dBi is the amount of focus applied by an antenna with respect to an “Isotropic Radiator” (a dispersion pattern that radiates the energy equally in all directions onto an imaginary sphere surrounding a point source). Thus an antenna with 2.1 dBi of gain focuses the energy so that some areas on an imaginary sphere surrounding the antenna will have 2.1 dB more signal strength than the strength of the strongest spot on the sphere around an Isotropic Radiator.
dBd refers to the antenna gain with respect to a reference dipole antenna. A reference dipole antenna is defined to have 2.15 dBi of gain. So converting between dBi and dBd is as simple as adding or subtracting 2.15 according to these formulas:
  • dBi = dBd + 2.15
  • dBd = dBi – 2.15
Specifying antenna gain in dBd means that the antenna in question has the ability to focus the energy x dB more than a dipole
Posted in Antennas

Tower Project Part 1

When I first started dreaming about having a beam antenna, I originally envisioned installing it on top of a 43ft telescoping mast. However, as I run all my outside radio-related changes by the Approver of All Things That Require Approving, that was shot down due to the lack of excitement about the required guy ropes. As a compromise (and an improvement), I won approval for a Rohn 25G tower up against the side of the house, bracketed to the house.

Well, over time that appeared to be less exciting (due to the proximity to the house) and to achieve the desired height I shared that I might need a few guy wires from the very top. That didn’t go so well. We re-entered negotiations. In the end, I won permission to install a 40-50ft Rohn 45G free-standing tower. No guy wires. Lots, and lots of concrete. Still, it’s far more than I hoped for originally.

Rohn 45G is significantly more expensive than Rohn 25G tower. While a ten foot section of Rohn 25 runs about $110, a ten foot section of Rohn 45G is almost $280. These are prices from R&L Electronics in Hamilton, OH. The store is less than an hour from my home.

I ended up purchasing a single ten foot section and a five foot section to go into the concrete base. The top six inches will protrude and have the connection point for all the top sections. I was intending to prepare the foundation and install ten feet on top to assist with leveling the tower. That was all I could afford, or so I thought.

Rohn 45G WaitingI received an email forwarded from a friend who knew I was in the market for tower parts. A gentleman up north of me was moving from his QTH and selling his towers. He had a number of sections of Rohn 45G to sell. I reached out and after about a week he accepted my offer. I acquired forty feet of Rohn 45G for about half of what it would cost me at the store. What a deal! When I inspected the sections at pick-up time, I was thrilled that the sections looked like new. They had only been in the air for about seven or eight years.

So here they sit, waiting for the contractor to come by to dig the hole and pour the concrete (in addition to the re-bar cage and pluming). Excellent!

Everything is proceeding as I have foreseen.

Posted in Tower

Push-To-Talk Foot Switch Adapter for KX3

Recently, I picked up an inexpensive BM-800 condenser microphone for my KX3. It works beautifully. However… I don’t like running in VOX. I get too many interruptions. So I need a PTT solution other than using the PTT button on the KX3. I’ve had this Heil FS-3 foot switch sitting in its box for over a year, just waiting and waiting for this moment to come:

FS3

 

The foot switch isn’t anything fancy, it just shorts to two conductors on the plug when the switch is pressed. It’s a good quality switch though, I do recommend it.

What I wanted to do was create an adapter so that I could use the foot switch to trigger PTT on the BM-800 microphone. To figure out how to do this I decided to look at the schematic for the Elecrtaft MH-3 hand microphone:

MH3

 

According to the schematic, the shield is the ground, the tip is the mic audio, and the rings (R1 and R2) are what control PTT. If I just shorted R1 and R2, that would cause the KX3 to TX. I didn’t care about band up and band down, so it seemed simple enough. Here’s what I came up with for a design:

PTT Box

 

 

I felt this was a good design to fit all situations, but I wanted to check and see what the wiring was like specifically on the cable from the BM-800. So I opened up the XLR end to see how it was wired:

photo07

 

As you can see here, the two pins show are wired together, and the ground is wired separately. Some testing with my Fluke made it clear that both the tip and the ring were wired together. So my design was good, and there was no need to connect the ring to anything.

I assembled the following parts:

And this is what came out as a result:

photo12Here’s a good look at the 1/4″ jack wiring (foot switch)

photo11Here’s a good look at the stereo jack wiring (BM-800)

photo10Here’s a good look at the 1/8″ 4-conductor jack (KX3)

photo14The closed container, the foot switch jack on the left and the KX3 jack on the right

photo13The closed container, the BM-800 jack on the left and the foot switch jack on the right

Does it work? You bet it does! I’ll post more pictures later of the complete setup when I get the boom and pop screen installed!

Posted in KX3

Shengyue BM-800 Condenser Microphone

Ever since I had my FT-950, I’ve been wanting a nice station mic setup. Well, late last year I switched from the FT-950 to my KX3/KXPA100 and it took me a couple of months to figure out that the range of microphones that could be used with the KX3 were somewhat limited. The KX3 just doesn’t like dynamic microphones. It needs a microphone with a load impedance of somewhere between 600-1500 ohms. A firmware update has been released to provide up to 20dB more mic gain, which allows some microphones (dynamic maybe?) to be used with the KX3 but I suspect that if you crank the mic gain up into the higher ranges of the settings it is less than optimal. So I’ve been keeping my eye out for a good, inexpensive condenser microphone.

I don’t know what motivated me, but I found myself browsing eBay for “condenser microphone”. I was somewhat stunned by the search results. There were lots of inexpensive ( less than $50) condenser microphones that *might* suit my needs so I started look through the styles and tech specs. I skipped over all the side speaking mics, I wasn’t interested in those. Then I found this gem: New-BM-800-Black-Condenser-Microphone-Mic-with-Shockmount

 

A quick search for the model number showed lots of other sellers and the microphone seemed targeted towards PC and Skype users. I knew that the KX3 worked with a lot of PC compatible microphones so this looked promising. The load Independence was > 1000 ohms. That was a good sign. The connecting cable ended in a 3.5mm stereo connector. Also Good. Frequency response seemed adequate, though I’m not an audiophile enough to know one way or another. It came with a shock mount, which I wasn’t going to assume was the highest quality but that was a plus. For $33.29 shipped, it was too good of a possibility to pass up. But I wanted to know more.

I found this YouTube video where someone unboxed the mic which gave me a good idea of what it came with. He even opened up the mic itself to show some of the internals, which showed that it used a AA battery so external power wasn’t needed: https://www.youtube.com/watch?v=XrYy64TgfVM

Some more searching led me to this discussion about “cheap condenser. It seems the microphones are possibly/likely rebranded leftovers from production runs for the ISK brand, which is pretty reputable in the audio world: http://forums.acoustica.com/bbs/viewtopic.php?f=4&t=14937. You can see some of the ISK models for same in the UK at this site: http://www.micsdirect.com/isk.htm. Also, here is the ISK main site: http://www.iskmic.com/.

So I took the plunge and bought one. It arrived last Friday. Now it’s picture time.

photo01The picture on the box is NOT what was in the box. I thought that was wierd but it matched with what was in the YouTube video.

photo02I actually took everything out and then put it back in for this picture, so everything is out of their wrappers and the battery is already installed.

1000x1000If you visited the ISK website, you won’t find this model there, but you’ll see lots of models that look too similar to be coincidence.

photo2The mic takes a singe AA battery for power.

photo1Another interior picture of the mic. The upper part doesn’t come apart easily so I didn’t try.

photo03A close up of the cable ends, which goes from XLR to 3.5mm stereo.

photo04A close up of the shock mount. It’s actually better than I thought it would be.
NOTE: The shock mount uses a 3/8″ mount, not a 5/8″ mount. You cannot use this with a Heil mic boom without an adapter.

So it *looks* good,  but how did it work? I contacted a friend who lives about 1.4 miles aware and we met on 28.360MHz for some testing. I performed before tests using the Elecraft MH-3 microphone and after tests with the BM-800. Of course, with the BM-800 mic I had to use the PTT button on the KX3, but my friend reported the audio with the BM-800 was better than that with the MH-3. He said the audio was excellent and the basses in my voice came through better.

Okay, so that’s one opinion, but it was enough to tell me that this microphone is good enough, and it looks like it will work well with the KX3. Deep, deep down I had always lusted after the Heil PR-781, but from everything I read it wouldn’t work (that well) with the KX3. Now I have something that looks similar (I know, I’m petty) and does work with the KX3. Now I just need a mic boom and I think I’m set.

Now I have something to connect to my homemade PTT foot switch adapter.

 

Posted in KX3

Review: PAE-Kx31 heat sink for the KX3 from WA4PSC

The KX3 is amazing QRP radio, probably the best in it’s class. One of the more remarkable features is it’s built in PSK/RTTY mode. Recently, the fact that when running 5-10 watts for prolonged transmit times causes the KX3 to heat up to a point where the temperature monitor will force you to scale back your power. While this is very annoying, it’s necessary  in order to protect the KX3.

In the KX3 online discussions, a number of aftermarket heat sinks have been developed for the KX3. After reviewing the various designs, I took the plunge and placed a pre-order for the PAE-Kx31 from Pro Audio Engineering. More than just a chunk of aluminum on the back of the Kx3, this promised to have several features that I wanted:

  • Fins for better passive heat transfer
  • No sharp edges to snack in a backpack, clothing, or myself
  • Anodized instead of powder coated
  • The ability to continue to use my SideKX end plates and SideKX LEXAN cover

I got word last week that the item had shipped and it arrived Friday (April 18th). Excited as I was, I couldn’t perform the installation until Sunday. Here is the step by step with pictures along the way.

IMG_0040The package contents included the heat sink, four replacement screws to accommodate the additional thickness of the heat sink base plate, an installation guide, and a small package of thermal grease.

IMG_0041 The heat sink in more detail.

IMG_0045The small packet which contained the four screws and the thermal grease packet.

IMG_0046The heat sink measures just a bit over seven inches long.

IMG_0047The heat sink is about one and a half inches high.

IMG_0048The heat sink is about five-eighths of an inch thick. Note there is a notch on this end of the heat ink base plate. This is to accommodate the lip of the SideKX LEXAN cover.

IMG_0044

IMG_0043The instruction guide is well detailed.

IMG_0053The one provided screw that is longer must go in the hold closest to the DC power supply.

IMG_0054You can see the size difference, accommodating the thickness of the base plate.

IMG_0055Removing the factory heat sink plate, you can see the original screws in the front row and the provided replacements behind them. Sadly, this means my brass ID plate from Arkay Engravers will have to find a new location.

IMG_0056With the original plate removed, the new heat sink is ready to go on. There are instructions for three different installations. I performed the first, which is a simple replacement of the original plate with the new heat sink. I did not use the thermal paste.

IMG_0058You may have to open your case and re-seat the locking nuts that the middle two screws attach to.

IMG_0057You can see these two screw holes next to the battery pack. When I removed the original screws, the nuts fell out of place and I had to fish them out. I attached these two screws first, and then attached the two on the end last.

IMG_0059Here the nuts are in place with the heat sink attached.

IMG_0060Behold, the heat sink is attached!

IMG_0061You will notice, the anodized black is an excellent match to the black of the KX3. It’s an excellent detail that was attended to.

IMG_0062Sitting on the legs, the heat sink doesn’t add any perceptible bulk to the KX3. The rounded radial fins help reduce that impression.

IMG_0064Also important, the SideKX LEXAN cover fits perfectly. That little notch on one end of the plate was thoughtfully included.

All in all, I think this is a very fine product. Howard Hoyt (WA4PSC) paid a lot of attention to the details of this aftermarket heat sink and I think it was worth every penny!

Coming soon, I’ll do a key-down time vs temperature chart comparing operation with the new heat sink versus with the stock plate.

Posted in KX3

Comments on the KX3 Extended VFO Temperature Compensation Procedure

So I am the very pleased owner of KX3 #3899, purchased used from an absolute gentleman of a ham (WB4OQX). I only just recently acquired the KXPA100 amplifier for the KX3 and sold off my FT-950, IF-2000, LP-PAN2, and LDF AT100Pro2. So far with the KX3 as a base station I’ve only run SSB, but I want to get the PKS31 and JT-65HF modes up and running.

To help out with this, I performed the Extended VFO Temperature Compensation Procedure two nights ago. I made some mistakes and performed the procedure again last night with much better results. I’m going to share my notes and observations so others can avoid my pitfalls.

Note:  I used the XG50 from Elecraft, which I assembled from a kit. I am relatively inexperienced with a soldiering iron, but I have a good soldering station (fine tip, temperature control) which made it rather painless. I highly recommend the XG50 for this. I also used a hairdryer for the heating element.

 1. On my first try, I applied the heater (hairdryer) to the radio as soon as I started data logging after removing it from the refrigerator. This was a mistake. This caused the temperature to rise too fast from the coolest point and the data gathering did not get a nice, wide spread of data points in the cooler temperatures. The second time around, I let the radio naturally equalize to room temperature (as observed before cooling it) and only then applied the heater.
2. On my first try, I kept the hair dryer too close and the temperature rose too quickly to the 52 C mark. How did I figure this out? When the procedure was complete and the data logging finished, I switched off the heater and let the radio equalize naturally back to room temperature. I watched the temperature drop and saw that the baseline frequency oscillated over 20Hz from the 550Hz. It should have been maybe 2Hz off, so I knew something was wrong.
3. On my first try, I attached the XG50 directly to the KX3. Doing so allowed the XG50 to be heated by the hair dryer due to its proximity to the KX3. I believe this affected the signal output, making it inconsistent. On my second attempt I attached the XG50 to the KX3 using a three foot coax cable which kept the XG50 well away from the heater.
After the second attempt at the procedure, I let the radio cool naturally and watched the temperature drop and saw that the frequency varied at most about 2-3Hz all the way down to room temperature from the 550Hz baseline. This was much better the the first attempt.
So now I have a reasonably temperature stable KX3, primed and ready for JT65, JT9, PSK31 and just about any digital mode I can throw at it.
Next up, my first foray into PSK31.
Posted in KX3