Of all the 500 series modular scopes made by Tektronix, the 547 is one of the most desirable due to its 50 MHz bandwidth and innovative dual timebases. When released, this machine was way-hot high tech, crammed with a mix of vacuum tubes and discrete semiconductors, and worth as much as a new car. I got mine through a friend who found it at a church rummage sale and paid $10 for it, complete with cart, some extra modules, and manuals for everything. Any problems? Well sure—the thing's been in service for 40 years, knocked about by at least two private companies (judging by the calibration stickers) and its original owner, the United States Navy. A short list:
- The dust filter that covered the fan was missing, because the bolts that kept the bezel on were sheared off—though the bezel came with the scope in the drawer of the cart, at least.
- The original power inlet was cracked, and missing its ground pin, which is more than a little dangerous.
- The fuse holder was chewed up and unable to retain the fuse and cap, which was missing entirely.
The mangled power connector (first photo) I replaced with a Hubbell miniature twist-lock connector, which was the only thing I could find that would fit the hole in the chassis. I had to file out the holes on the connector a bit to make the bolts fit, however. The second photo also shows the new fuse holder.
I fixed the dust-filter by buying a package of 12 inch square “StrataDensity” fiberglass filters and trimming them a bit to fit into the filter bezel. I can't say these have the best dust-filtering performance, but they're certainly better than nothing. I also cut two plates of expanded metal grate to sandwich the filter in the bezel, keeping it from being sucked into the fan or from falling out of the back. The bezel is now attached through the original bolt holes (I haven't made hard modifications to anything that was original to the scope, out of respect for history) by means of two standoffs and small 4-40 screws.
These small fixes are all I needed to get the scope up-and-running. I don't yet have the signal sources necessary to really calibrate it properly, but it's good enough as it is and works well for the mostly-qualitative measurements I've been doing lately. Now all I need is a bottle of painkillers for the chronic back pain I'm sure to acquire lugging this boat-anchor around. ;)