Sorry, I've been a bad blogger.

I just noticed that I had a number of comments awaiting moderation and I just published them all. Sorry about that folks.

Used to be Blogger would send me an email when I had comments, and I could moderate them then. Apparently, they stopped doing that about a year and a half ago.

So, if you left me a comment on one of my articles, it's published now. And I may have even answered it....

I'll try to keep on top of this in the future.

Schematic for the "Novice" Transmitter

Schematic for the "Novice" Transmitter

I guess it has taken a while. I wrote about my Novice transmitter over ten years ago in January of 2019 as one of my first articles in this blog. But I never published a schematic.

Well, the wait is over. This summer I took some time to hand-draw a schematic reasonably neatly. At least neatly enough for someone else to make heads or tails out of it.

The result is in the image on the right. The circuit is pretty simple.

A couple of notes on the tank circuit. The coil is 1 3/4" diameter, 12 turns, about 7/8" long, which computes to be about 6.4 uH. A typical pi network for a 6146 at 7 MHz should be L = 6.2 uH, C1 = 90 pF, C2 = 500 pF. So it seems my design is pretty close.

The keying arrangement is unique. The oscillator is cathode keyed, but the PA is biased beyond cutoff for Class C operation. When properly the grid tuned circuit is properly adjusted, there is little to no chirp.

This radio works pretty well on 30m, too. The crystals I have for 30m are HC-49U crystals soldered in FT-243 housings. These drift a little bit key down, likely due to the high crystal current. I added a 100 ohm resistor in series with the crystal to limit the current.

E. U. N.

Some time ago, I read a blog article on how to prioritize requirements. The author called it N-U-N analysis. The letters stood for Needed, Useful, Nice. I thought this was a brilliant idea, but the acronym was awkward, because there were two "N"s. I decided to traded the first for a better synonym: Essential. Essential, Useful, Nice. E. U. N. This is a powerful organizing principle.

I recently was dealing with a ham radio project list that had gotten too long. I had a number of great ideas which I had added to the project list, so it crossed several pages of my station log. This made actually finding something I could work on difficult -- especially when dealing with projects that could actually add value.

Mulling this over, I decided I needed to apply the same principle to my project list. But what was Essential, and what was merely Nice? and how about the Useful projects in between?

I decided to break it down this way:

• Essential - fixing what is broken
• Useful - allowing new capabilities
• Nice - anything that might be a nice addition

I organized my long list, and low and behold it was very helpful. I only had a few projects in the Essential section, but one of them I had basically forgotten (fixing a broken switch contact on the Ameritron AL-80A).

Several of the projects were in the Useful category, and I'll be getting those done sooner. Everything in the Nice category can wait a bit.

I can't say that this exercised has helped me get anything done sooner, but now I know my efforts will be focused on the most valuable projects.

Rebuilding the HF4B

It's been a long time since I picked up the Butternut HF4B project from a friend. I decided it would be a good fit at the Fulton County QTH. It's small enough to be supported by a mast, and will turn with a tiny rotator. I took all of the pieces to Fulton County, disassembled and cleaned everything, and took stock of what I needed.

The basic components seem to be OK. One of the 1/2" tubes is damaged with a gouge near the end, nearly ran over by a lawnmower no doubt, but will be serviceable. One of the 1 1/8" element support tubes has a crack. I've looked for a replacement locally without luck. I think for the moment I'll use a clamp to hold it together.

Two of the four doorknob capacitors have cracked. I managed to find five 75 pF caps at a hamfest a couple of years ago. I bought five in order to have a spare. These things are fragile.

All of the stainless hardware is serviceable despite being out in the weather for over 25 years. The U-bolts, however, are another story.

I don't know what genius thought it was a good idea to sell an antenna with zinc-plated U-bolts, lock washers and nuts. After 25 years of weather, they are rusted junk. Some of the legs broke off when trying to undo the nuts. Those that didn't are so rusty as to be unusable for any purpose.

I ordered replacement U-bolts from McMaster-Carr, who had exact replacements for a reasonable price. Except these are stainless steel.

With replacement hardware in hand, I started to re-assemble the antenna. The wires of the bowtie elements needed replacement. This antenna has eight of these, but only four survived to make it home with me. Of these, only one is intact. I used it to make measurements and make eight identical replacements.

I hit the a snag assembling the first element. The clamps that hold the vertical tubes aren't tight enough to keep them from rotating on the support tubes. Butternut replaced these sheet metal clamps with U-bolts in a later release, which would work better. This requires sleeving about four inches of the vertical tubes.

I guess that's what I'll have to do.

Demise of the 80/40m Dipole

Sad to say, I recently lost my 80/40m trap dipole. Which is too bad, because it was a good antenna. I used this antenna from four different locations in Georgia: Gwinnett, Floyd, Walton and Fulton counties. I made thousands of contacts on this antenna. It had been the first antenna I put up at Floyd and Walton counties, and the only antenna at Fulton county.

It was last up at the parsonage in Fulton county. Apparently a group of teens was doing some volunteer work near the parsonage. They saw the rope tied off to the parsonage fence and thought it was something other than it was, so they untied it.

After this, half the antenna fell down to the ground and was left there. When the landscapers came by to mow the grass, they ran over it....

So, about 80 feet of rope, insulator and one of the traps was completely destroyed. The other half of the dipole is still intact, up in the trees. But most of one element is gone -- clearly the landscapers threw it away.

Plan is to design an 80/40/20m trap dipole, using traps made with coils and capacitors, since they have much higher Q than the coax cable traps. I'll also place the traps on frequencies well off the operating frequency.

Uh Oh. Not Good.

Well, if it isn't one thing, it's another. After celebrating getting the A3S/A743 rotating again, I've found a problem. The SWR shifts I mentioned? On a dark night, I went outside and looked up at the antenna while WSJT-X was transmitting on FT8 trying to contact someone. I tried this on 40 and 20m.

I observed one of the 20m traps on the driven element light up with arcing using 100 watts. It was visible in the drain holes and end caps of the trap.

At the very least, I'll need to take the driven element down and rebuild it.

Update: I've tried this experiment on 15m, and I see no SWR shifts even using 500 watts. I think the problem may be confined to the 20m trap(s).

Rotating Again!

Well, it didn't take months after all. As I wrote last month, my A3S/A743 had been stationary since December. But with the beautiful spring weather here in Georgia, I managed to get to the top of the tower and finish the installation.

It's now rotating freely, as expected. It's really good to be able to use the beam as intended, and not have it fixed roughly east.

I do wonder if the A3S/A743 needs repair, however. I'm still seeing occasional SWR shifts at 100 watts on 40 and 20m. I'll need a gin pole to take the antenna down to refurbish.