A new oscilloscope

Saw someone at the TARC swap meet with one of these little Tektronix 222 DSOs for sale, so I bought it. Terrific timing since my Hitachi oscilloscope died a while back and I still haven’t gotten around to looking into it.

Tektronix 222 oscilloscope
Tektronix 222 oscilloscope

It’s little, and doesn’t have a lot of capabilities but I think it will do pretty much everything I need (at the moment). It comes with two scope probes that are permanently attached. It’s designed to be powered with an 8V SLA battery, but it looks like batteries with the right form factor and voltage aren’t readily available anymore. I did find a promising looking battery replacement project though. This one didn’t come with a battery, but a standard sized power jack lets you power it with wall power. It’s even got a RS-232 serial port!

The scope seems simple enough to figure out how to use without a manual, and I was even able to find a service manual online to download.

Here I’ve got one of the channels measuring the output from one of my Etherkit Si5351 breakout boards. I don’t remember what I have my RedBoard making the Si5351 do, but I seem to be getting a pretty good signal out of it.

Tektronix 222 display
Tektronix 222 display

A new power supply

One of my acquisitions from today’s TARC swap meet was a variable power supply. The person I bought it from acquired a bunch of these from a school district surplus auction. I’ve been wanting to get a variable power supply for the workbench, so I bought one of them for $20. Seemed like a pretty good deal. Almost grabbed a second one from him.

Variable power supply
Variable power supply

Banana jacks provide AC and DC outputs, and voltage for both is controlled by the knob on the left. Two meters show DC volts and amps, but if you’re using the AC output, you’ll need to measure it yourself.

The panel indicates the power supply will do 0-20 VDC and 0-25 VAC. With no load, the power supply topped out at 35 VDC and 26 VAC. This is an unregulated power supply, so any load is going to bring the voltage down.

Max 35VDC unloaded
Max 35VDC unloaded
Max 26VAC unloaded
Max 26VAC unloaded

Getting inside the power supply requires removing a total of 18 screws (6 on each side, 6 on the top). Seems a bit excessive to me, but I didn’t design the thing. Once the screws are out, removing the top exposes the innards.

Power supply innards
Power supply innards

Not much to it inside. There’s a big beefy transformer which accounts for almost all of the power supply’s weight. Voltage control is performed by the variac. A large (and loud) 120mm fan (lower right) provides cooling.

The key just turns a metal plate that flips the actual power switch on or off.

Power switch
Power switch

The cooling fan gets its own power supply so that it’s not affected by changing the output voltage.  It’s just a 12V wall wart that gets powered from the AC input I think (haven’t traced any of the wires to see what goes where).

Cooling fan power supply
Cooling fan power supply

Plenty of modification potential with this power supply. I’ve got a small list of easy ones that I think I’ll make:

  • Replace the key with a regular switch
  • Switch out the banana plugs for 5-way binding posts and Powerpole connectors
  • Replace the fan with a quieter one

This seems to be a pretty sturdy power supply designed for the harsh environment of a high school lab. Everything inside looks to be in pretty good condition.

An Instructograph

While I was rummaging around through the club’s storage room yesterday, I came across an old Instructograph machine. I’m not sure how old this particular unit iss, but it looks like it has definitely seen better days.

Instructograph label
Instructograph label
Instructograph
Instructograph
Instructograph
Instructograph

It’s a paper tape based Morse code trainer with the Morse code encoded as holes in the paper tape. Along with the Instructograph were nine tins containing other tapes. Seven of them were rusted closed so I didn’t try to force them open. A couple were left open, including the one already on the Instructograph.

Instructograph tape tins
Instructograph tape tins
Instructograph tin
Instructograph tin
Open instructograph tin
Open instructograph tin

The Instructograph is essentially just an automatic straight keyer with an audio oscillator. As the paper tape moves between the contacts, the key is closed where the dots and dashes are punched out of the paper and generates the tone. The tapes are double-sided, so when you finish playing one, you just flip it over, thread it back onto the machine and play the other side.

Instructograph contact switch
Instructograph contact switch

I think the tape speed would have been controlled using this lever on the panel.

Instructograph speed control
Instructograph speed control

No idea if the Instructograph still works or what kind of condition the innards are in. The paper tapes are in somewhat delicate condition and I’m not sure if they’d hold up to much playing anymore if the Instructograph did work.

Special Event: USS Yorktown (CV10) Commissioning 75th Anniversary Day 1

The special event station for the Yorktown’s 75th commissioning anniversary went fairly well. Operations started off with one of the club members operating the Waterway Net on 40m from the club room, and then we got set up to start calling on 20 m. I spent a couple hours or so working stations on 20 m, moving around occasionally because of QRM. Many stations were coming in pretty loud and clear, although at times the fading got a bit deep.

We tried to move down to 40 m after noon, but got a report that our audio had a lot of RF noise in it, so we spent some time trying to figure out where it was coming from. We ended up narrowing it down to a few culprits: noisy laptops and a noisy power supply built into the FT-897. Something we’ll have to troubleshoot further.

We ended up spending the rest of the afternoon up on 20 m doing a mix of SSB and digital, but with storms moving in, there were loud static crashes all over the place, and we only made a few more contacts. With the band dead, storms getting closer, and a tornado watch issued by the weather service, we decided to call it a day around 3ish.

Finished the day with 55 contacts in the log. Not bad for a few hours of casual operating.

 Band   Mode  QSOs 
     7  LSB     10
     7  PSK3     2
    14  OLIV     1 
    14  RTTY     5
    14  USB     37
 Total  Both    55

Special Event: USS Yorktown (CV10) Commissioning 75th Anniversary Day 0

Even though tomorrow is the actual day of the USS Yorktown’s commissioning, I thought I’d spend the afternoon in the club room activating WA4USN and get a few more contacts in for the special event. I was joined by two other hams for the afternoon.

Things didn’t quite go exactly as planned, but still went fairly well.

After spending some time figuring out the Yaesu FT-897 that was sitting where I expected the Kenwood 570 to be, I started calling CQ on 20 m. After a few calls, we (WA4USN) got a call over the repeater from a ham at a radio station set up at a nearby Boy Scout camp asking if he could put some Cub Scouts on the air with us for the special event.

Always a good thing to get on the air with Scouts, so we talked with a group of Cub Scouts (Webelos) and then got back to HF. Spent some time calling, and then another call on the repeater with another group of Scouts. Rinse and repeat.

After the third group or so, we decided to just give up on HF and spent the rest of the afternoon talking to Cub Scouts (I was too lazy to break out the headphones).

So even though there were no HF contacts today, I still consider it to be a pretty good day on the radio. Talked to 21 Scouts in total, mostly Cub Scouts. Many weren’t terribly talkative, but a few were downright chatty. Some of them learned about the Yorktown. All got exposed to radio and it seemed to have generated some interested at the camp.

Tomorrow will be all HF though.