Sometimes it seems like there aren’t enough hours in a day. I know that’s hard to imagine – after all, we’re retired and usually don’t have any pressing matters on our daily schedule. But, we’re active and have a number of things we like to do on a regular basis. None of it really can be regarded as work – I define work as any activity that occupies my time when I’d rather be doing something else.

My day usually involves a couple of hours on the pickleball court, a couple of hours practicing guitar, and sometimes I get on the air with my ham radio and make contacts all over. Sometimes I may have a household project to tackle. Donna is busier than I am. She plays tennis as well as pickleball, lines up a couple hours of work doing various things for others here in Viewpoint, she’s on the board for the Viewpoint Concert Band and also volunteers as a street captain. And she’s actively involved in the tennis club. Now she’s learning to play golf too.

I’ve been taking a deeper dive into electronics – particularly vacuum tube amplification. To that end, I recently bought a couple of pieces of equipment that will allow me to take a more certain approach to troubleshooting, maintaining and repairing amplifiers. I bought a signal generator – more specifically a Direct Digital Synthesis (DDS) signal generator that can create various waveforms and frequencies. I also bought a Rigol DS1102 Digital Storage Oscilloscope (DSO).

I used the DDS signal generator to feed the input of the DSO and calibrate it. I also made a resistive, non-inductive dummy load to act as a speaker load when I test an amplifier. Amplifiers should never be operated without a load – usually a speaker. But to avoid annoying, loud tones while testing, a dummy load that doesn’t produce sound is the way to go. The signal generator can produce a consistent, known waveform to aid signal analysis. I also made an input jumper to connect the DDS signal generator to the amplifier input.

Now I can create an input of a known frequency and amplitude into the amplifier and check the signals progress through various stages of amplification with the oscilloscope.

After building and playing my Dumble-style Trinity OSD amplifier, it became apparent to me that my Trainwreck-inspired amp didn’t sound as good as it once did. I built that amp nine years ago and it rattled around in the basement compartment of our motorhome for eight years.

I pulled the Trainwreck chassis and ran a 100 kHz signal though it. It appeared as though the tubes were breaking up and distorting earlier than I expected. I’d recently replaced the preamp tubes, so I figured it was time to replace the power (output) tubes – they were the nine-year-old original tubes. I had a matched pair of EL34 tubes on hand so I changed them and reset the bias. I made a boneheaded mistake doing that. The idle current through the tube should be set with a bias potentiometer to around 42 milliamps. I couldn’t get it under 100 milliamps! This was no good. After futzing around and scratching my head, I realized I was still running a 100kHz signal through the amp. It wasn’t idling – it was powering up the signal silently into the dummy load! I disconnected the signal generator and made the bias adjustment with no issues.

The amp sounded much better after getting new power tubes, but I want to analyze the circuits further. I wanted to only make one change at a time, but I think I see a couple of things that I can improve to make this high-gain amp operate with less background hum. I’ll get busy on that soon. I may offer guitar amplifier maintenance and limited repair service for something to keep my mind active and make me feel useful.

I made myself useful last week by preparing Memphis-style dry-rubbed babyback ribs on the Traeger wood pellet-fired smoker/grill.

Donna served it with a medley of roasted vegetables and a loaded baked spud.

It looks like a small portion of ribs – it’s only two bones. But let me assure you, Donna and I had second servings of the ribs. They were outstanding!

Donna came up with an Asian-inspired flank steak recipe that also hit it out of the park!

The weather here in Mesa, Arizona keeps getting better and better. For the last week, we had highs in the mid-to upper 80s with overnight lows in the upper 50s. Today the forecast calls for a high of 82 degrees and the long-term forecast calls for highs around 80 and overnight lows in the low to mid 50s. Very pleasant!

*Just so you know, if you use this link to shop on Amazon and decide to purchase anything, you pay the same price as usual and I’ll earn a few pennies for the referral. It’ll go into the beer fund. Thanks!