- 2024
- Dec
- 15
A Waterman OCA-11A “industrial / pocket” oscilloscope - Part 2: Tubes!
I picked this device up at the MARC hamfest in North Canton. The seller stated “Someone removed all the tubes except one” and he was right. 4 12AX7 and 1 6U10 were required to fill all of the sockets again.
This is the device in question. It looks like it requires both a horizontal and vertical input, but I’m not sure.
Thanks to Bob @ hamtubes.com, I was able to acquire the necessary tubes. I’m not sure why they were removed, they aren’t really that much unless you want old RCA branded 12AX7. The 6U10 compactron isn’t expensive at all. I chose Russian and Chinese 12AX7 because this is an instrument, not an amplifier.
A little bit about one of these tubes: the 6U10 “”compactron” was the last gasp of the tube industry. Packing up to 4 devices in a single shell, this was an attempt by GE to reduce the number of tubes required for a television set. Had these come out before the transistor era started, we might have seen more elements in a single tube, but we didn’t, and the rest is history. This particular device contains 3 triodes - probably why it was removed by the previous owner.
So let’s open it up and populate things. Indeed, it is empty in here:
And now it’s full:
Some of these tubes were hard to get in to their respective sockets.
I did notice the one remaining tube was Waterman branded. That’s too bad, the others probably were too. I wonder who made these - maybe I’ll pull it out sometime and see if it has an EIA code on it.
Ok, so…let’s try it. Checking across the line cord I get…nothing. Mmmmm that’s not good. No external fuses, so what’s wrong here. Start with the line cord, it goes to the fuse, then to the switch, then to the ….nothing.
Power switch is bad. It’s pretty corroded, so no surprise. Well, I’m out of time for this particular device at the moment, so a note and set it aside. Stay tuned for the next part where we turn it on for reals!
Next part of this series: Coming soon.
Previous part of this series: https://wereboar.com … pocket-oscilloscope/