- 2025
- Dec
- 31
An EICO 902 Harmonic Distortion Analyzer Part 1: What’s going on?
While the Hallicrafters S-38C is waiting for a check before plugging it in, I’m starting on this analyzer. This is a standard null-type analyzer of a nature similar to many others. You input a frequency, null out the fundamental, and what’s left is the distortion. It’s spat out on a meter and scope terminals.
These devices seem to go for a lot of money, so I was quite surprised to be able to pick it up at Dayton 2025 for $30. I believe the gentleman I purchased it from was the original owner, and the device appears to have been factory built.
It’s in need of a cleaning:
Inside it’s dusty but relatively clean. A little rust on the transformer.
And the bottom is nice and clean and shows almost no trace of work.
The only imperfection I can see is this little wire snip, and I’d say that was left from the original build.
The top has one modification, someone cut open a tube shield. It was suggested that perhaps this tube ran hot and was not operating properly (thus the blackened metal,) and this was an attempt to make it work. Rather crude, and I may see if I can get a new shield and see what happens. If this is indeed an issue, I’ll cut the top to be a bit more clean than this let’s just chop-job it.
So, it’s in great shape. There’s some wax paper capacitors that will need changed, but it’s good enough to try out. First thing, is it needs a new cord. The original is barely hanging on at the input to the chassis, so it gets a new polarized cord. It also needs a pilot bulb lens, but I have some other lamps that may fit here. Fuse is present and not blown, but the glass is cracked, so that’s changed out. Plug in, and…
Nothing.
Turns out the power switch is completely open.
I only had one jumper with me, and it was in use as a temporary fuse. So, I decided to call it until I could get a proper fuse in the unit, at which point I’ll jumper the switch temporarily.
It looks like I can get this component apart to see what’s wrong, so I may do that in the near future. Stay tuned!
Next part of this series: Coming Soon.