Computer-Controlled Switch System

TASS (Totally Awesome Switch System) is a general purpose 8-port DC-150 MHz relay-based switch. The hardware is designed to be very generic, with an inexpensive processor such as an Arduino providing the system logic. Control is via USB, with Ethernet and other interfaces also available.

The TASS can be configured several ways, and multiple boards can be combined to create large switching systems. The TASS has many uses, from switching signal sources on a test bench or in a laboratory, to selecting receive antennas and filters in a ham or SWL station.

The TASS system has two boards:

• The TASS-R relay board, which does the mechanics of signal switching and provides a very simple 10-pin interface.
  
• The TASS-SHIELD board for use with an Arduino Mega 2560 microcontroller. The TASS-SHIELD allows up to four TASS-R boards to be controlled simultaneously.

Both boards are available now from TAPR as kits. They use through-hole parts and don't require any special assembly techniques.

The final component is open source software for the Arduino that acts as an interface between a host computer or other input system, and the switching hardware. The software is available for download from TAPR.

An introductory video is available here.

Software and documentation can be downloaded here.

You may order the TASS-R and TASS-SHIELD boards here.

Taylor Swift and My KX3

In May, I bought an Elecraft KX3 radio kit with almost all the options at Hamvention. Out of stock in Dayton, Elecraft shipped the kit to me and it arrived about two weeks later.

After some confusion on my part about receiving some wrong hardware, I built the kit and as I wrote here, I initially thought the receiver was deaf. Elecraft came to the rescue and had me install the default configuration file because I probably messed up some settings that deafened the receiver.

As I wrote back in June, "the receiver came to life after loading the defaults," but despite what I wrote, I still thought that the receiver was not that receptive and not living up to its reputation.

My spouse and daughter went to Gillette Stadium to see Taylor Swift in concert on a Saturday evening in July, so I had the house to myself for a good hunk of the day and planned to use the time to install the 2-meter receiver in my KX3.

About 45 minutes into the process, I had to disconnect the cable that mated the HF antenna connector assembly to the automatic antenna tuner circuit board. Then I had to remove the automatic antenna tuner circuit board. 

After doing so, I noticed that the cable I had just disconnected seemed to flop around too easily. Examining the cable, I saw that only one strand of the stranded wire cable was actually connected to the HF antenna connector assembly! When I touched the cable, the remaining strand of wire broke. too.

I'm not sure what caused the cable problem. I may have broke it during the kit assembly, but I don't know how because I only had to deal with the cable briefly during assembly. It was not like I was moving it around a lot and weakening the solder joint.

Anyway, I closely examined what I needed to repair, but there was no way I could fix it. My eyesight isn't what it used to be and even with magnifying glasses, I was not sure where the cable was connected to the assembly. And even if I figured it out and soldered the cable to the assembly properly, the cable might now be too short to mate with the automatic antenna tuner circuit board. 

I called Elecraft Monday and explained my plight and they agreed to send me a new HF antenna connector assembly, which arrived a week later.

Meanwhile, serious family health issues required my attention and there was little time for radio throughout most of August. The health issue was resolved two weeks ago and after the dust settled, I hunkered down and began working on the KX3 again.

Monday evening, I replaced the HF antenna connector assembly and Tuesday evening, I finished installing the 2-meter transverter. After buttoning up the radio, I connected it to my 40-meter dipole, powered it on and held my breath. 

The radio came to life tuned to WTIC (1080 kc) and the Red Sox game was in progress. I immediately noticed that the receiver sounded a whole lot better than before the Taylor Swift concert.

I tuned up and down the AM band and could hear one or more stations on most of the AM channels, which was not the case before Ms. Swift took the stage. I switched to the HF ham bands and the receiver seemed much more sensitive than before.

Now I was worried about the transmitter. Was it stressed transmitting into that single strand of wire? I inserted my HF SWR/watt meter checked the transmitter's output and it did not seem worse for wear with the meter measuring 10 watts more or less.

I am not an engineer, just a ham who has been around the band a few times, so I don't know if the single strand of wire was the cause of the receiver's deafness. Would the receiver care if it was connected to the antenna via a single strand of wire or multiple strands of wire? My guess is not and perhaps there were other issues with the HF antenna connector assembly.

Anyway, I am very happy with the KX3 now and plan to build the PX3 on Saturday when my spouse and daughter go to the Big E to see Kansas in concert.

Building the KX3

The "correct" standoffs for my Elecraft KX3 kit arrived in Monday's mail. When I opened the package, I thought that the correct standoffs looked exactly the same as the incorrect standoffs. Did Elecraft send me the wrong standoffs again?

I doubted that they could make the same mistake twice and upon further investigation, I discovered the error of my ways.

Although, the five standoffs look the same, four take a 2-56 size screw while one takes a 4-40 size screw. I could not tell the difference until I tested each standoff with a 2-56 and 4-40 screw.

The inventory list in KX3 assembly manual deserves some of the blame for my error. The list shows the 2-56 standoff as being hexagon-shaped and the 4-40 standoff as round (see figure above). In the kit I received, all five of the 5/15-inch standoffs were round, so when I saw there were no hex 5/16-inch standoffs, I assumed I had five 4-40s and not four 2-56s and one 4-40.

Anyway, now that my inventory of kit parts checked out, I began assembling the kit.

I took my time and assembled the kit very carefully exceeding the 3 to 4 hour estimates for kit completion by about two hours.

I held my breath when I powered up the radio and was happy to see the KX3's LCD light up and display a cacophony of information, while its speaker emitted the sweet sound of ether. Instead of referring to the manual, I plunged right in and started pressing buttons and turning knobs and in a short time, I reached the conclusion that the KX3's receiver was deaf.

I monkeyed around with the buttons, knobs and various menu settings trying to bring the receiver to life without success. I opened the radio and reseated some of the pc boards, but still no luck. Getting nowhere fast, I called it quits for the day, but penned an e-mail to Elecraft describing my radio's predicament.

The next morning, Howard, K6IA, from Elecraft phoned me. He guessed that I had fouled up the KX3's settings and deafened the radio's receiver. He emailed me my radio's default settings file and suggested that I use the KX3 Utility software to load the defaults into the radio and then call him back, which I did.

Howard was correct and the receiver came to life after loading the defaults. I asked him a few questions while I had him on the phone and then thanked him for his help.

Next on my to-do list is to install the 2-meter transverter in the KX3 and build the PX3 panadpter. (I held off installing the transverter while assembling the KX3 because I wanted to be sure that the KX3 worked before complicating matters with the addition of the transverter.)

Bear With Me

I'm still waiting for the standoffs from Elecraft.

USPS originally estimated delivery on Saturday, but they were not delivered and USPS tracking indicates that they are now in transit from the Springfield, Massachusetts USPS facility. Maybe they will arrive Monday, maybe not. I am not holding my breath.

So while I waited impatiently for the standoffs last week, a black bear visited and dined on the contents of our bird feeder Thursday evening. Here are the videos my daughter and I took while sitting in her SUV observing our visitor.

The Standoff Standoff

I planned to assemble my Elecraft KX3 kit this week.

Over the weekend, I cleared a place to build the kit, rolled out the anti-static mat and connected it and the anti-static wrist strap to Earth ground.

It was a very busy weekend and that is as far as I got, so I planned to work on the kit each evening after my day job.

Monday, I unpacked the kit and did an inventory only to discover that my kit had four incorrect sized standoffs. After completing the inventory, I phoned Elecraft and they shipped the correct sized standoffs on Tuesday.

The standoffs are needed early in the kit assembly (the 5th step in the assembly instructions), so there is not much point beginning the kit assembly and then stopping to wait for the parts to arrive.

I was hoping to have the KX3 ready for the VHF contest this weekend, but that prospect does not look good.

Arrived

My First Heathkit ― The HR-10B Receiver

Yesterday, UPS delivered the Elecraft KX3 transceiver kit that I ordered at Hamvention. UPS also delivered an anti-static mat and wrist-strap that I ordered to use while assembling the KX3.

I have built plenty of Heathkits in the past and did not need any stinkin' anti-static devices. However, the KX3 kit is not your father's Heathkit.

The KX3 kit is a no soldering needed kit. Basically, I build the KX3 enclosure and plug-in various preassembled and tested pc boards. Those boards contain sensitive components that may be damaged by Electrostatic Discharge (ESD) simply by touching them, thus the need for the anti-static devices.

Last night, I unpacked the box from Elecraft and checked that everything I ordered had been delivered (it had). Then I began reading the kit assembly manual and plan to build the radio this weekend (3 to 4 hours are required to build it).

Printed Circuitry - Remco Science Kit

I got my feet wet in electronics (which I know is kind of dangerous) playing with this educational toy. Hours of fun for only $1 – it is amazing what a dollar could buy back in the early 1960s.

Surfin’: What a Deal, But Only Until Monday

This week, Surfin’ scopes out a real deal for the do-it-yourself ham radio crowd.

Surfin': Got Kits?

This week, Surfin’ considers those other vintage ham radio kits.

Surfin’: Got Heathkits?

This week, Surfin’ celebrates Heathkit’s reentry into the kit business.

Surfin’: Updating Surfin’

This week, Surfin’ revisits and updates recent installments of itself.

Old Heathkit Manuals Forced Offline

"Even though the company (Heathkit) stopped making and selling kits back in 1992, it apparently just sold the copyrights on its old manuals to another company, which is going around forcing any old manuals offline and demanding people buy them instead..."

Read all about it here.