Some time ago I restored a Knight-Kit 83-Y-135 signal tracer.
This is the mostly finished project. I keep forgetting to take the “before” photos.
I believe the knobs are original. Most photos of the 83-Y-135 show it with a lighter gray front panel with smaller red-ish knobs …
… such as this photo from NostalgicKitsCentral.com, the Knight 83-Y-135 page at RadioMuseum.org, F. Stephen Masik’s post on the Antique Radio Forum web site,
Flinx’s blog post about his 83-Y-135 restoration, and in the scanned manual at the Boat Anchor Manual Archive (BAMA).
However, there are a few sources that show the older dark gray panel with larger knobs that appear similar to mine,
such as this page from the 1962 Allied Radio catalog,
the cover of this manual reprint from RadioReprints.com,
and photos from an eBay auction.
I essentially re-kitted the unit. I stripped everything off the from panel and the chassis and cleaned everything up. The front panel had some rust stains on it,
so I used some Dupont No. 7 auto polishing compound on it.
I was able to remove the rust stains, but I faded some of the silk screen lettering pretty badly.
If I recall correctly, I cleaned up the old hardware with a Dremel tool with a wire brush. It came out pretty nice.
I did use the Dremel with wire brush to clean up the original binding posts. I think I just cleaned the plastic with Simple Green.
I think they also cleaned up nicely.
If you look closely, you can see the shouldered fiber washers that insulate the binding posts from the front panel.
The original washers were in bad shape, so I replaced them with new. You can still buy them from Mouser, although they are made by Keystone rather than Waldom. I’m showing #6 washers here, but I just checked and I actually used #8 size, Keystone part number 3065.
The back side takes flat fiber washers ...
… again replaced by new ones. Despite the photo above, I actually used #8 size, Keystone part number 3372.
Per the instructions, I used a shouldered washer on the front of the black (ground) binding post ...
… but left off the flat washer on the rear, so that the binding post is grounded.
A previous owner had replaced the Amphenol 75-PC1F connector with a bulkhead-mount BNC connector, but had incorrectly used a non-insulated connector. Grounding is critical in a high-gain circuit such as a signal tracer to avoid hum from ground loops. The original 75-series connector was insulated from the front panel by fiber washers. It was intended to be grounded to a terminal strip near the 6AU6 tube in the first stage of the amplifier.
I installed a modern insulated BNC jack to restore the originally-designed grounding scheme.
Knight didn’t supply star lock-washers for the terminal strips. I didn’t trust just the screw and nut to provide a good low-resistance ground connection,
so I fired up my Ungar iron with a 4039 element and tip and soldered the terminal strips to the chassis.
I also soldered the mounting plate and tabs of the re-stuffed electrolytic to the chassis.
The wiring instructions start at the usual place: wiring up the heater circuit, along with some of the front-panel controls.
We’re nearing completion.
The wiring wasn’t too complex, so it was rather pleasant to rebuild the kit.
Fortunately the eye tube is good.
I described my method for making the probe in a previous post.
I checked the wiring against the resistance chart in the manual before applying power.
Why stick with one meter when you can use two?
The finished restoration ...
… in its new home on the bench.