Sell, Restore, or Part Out Old Scope?

[Justin Thomas]

Hello all,

I guess I'm seeking opinions here...

I've got a 1964 Knight GK2000 that I got for nothing and don't know what I should do with it. It powers up and some of the knobs do stuff, but I don't know how well this thing works, if at all, or where to begin to use it. It's a beautiful piece of equipment on the inside, with a date and name and some handwritten notes on the chassis; I almost don't want to part it out. It's full of old CC resistors, some usable tubes, and a decent chassis to build other goofy-looking stuff on. I don't know whether it's worth restoring or getting any info on, and I might be willing to give it away to a good home for shipping costs. Anyone have any advice? Thanks in advance!

Justin Thomas

[bob p]

Old scopes can be heavy and expensive to ship. Depending on how complex it is, and if it uses all generic parts, it might not be too hard to rebuild.

Some of the older Tek scopes use generic parts, and some use proprietary chips. Whether or not your scope is worth the effort may depend on whether or not it uses proprietary chips and whether or not they're available. The "generic" Teks are highly regarded and in demand.

I have an old Heathkit 500 kHz scope that I bought for 99-cents. It works, but not very well. I was thinking about rebuilding it for audio signals. Its all tube and its pretty simple inside. I imagine that it may just need tubes and caps, or maybe some resistors. And a probe. There's not really anything else in there, so how hard can it be to fix? Its probably not worth the cost and effort, but it would make a fun restoration project. I'm still trying to find the book. If anyone has the book for a Heath O-10, please lemme know.



HTH.

[Enzo]

Heathkit O-9, O-11, and 10-10 are here:
Heathkit Schematic Diagram Archive

Heath O-10 schematic is here:
heath_schematic

[bob p]

Thanks, Enzo. I had never been able to find the O-10 schematic.

Now you wouldn't know where the assembly manual is hiding, would you?

[imaradiostar]

I've found that some old scopes can be a great source for parts, mostly for interesting power transformers and unconventional but excellent quality tubes for guitar use. I've collected a number of 6u8's and 6gh8's from old scopes as well as some 6au6's and a bunch of other more "oddball" tubes.

I think a tube scope can be great if it's in good shape but you may be better off purchasing a "restored" Tektronix tube scope that's been calibrated and is likely to last many tens of years. By using a 10x probe you can get by with a cheap/modern scope from ebay until you care to buy a "serious" tube scope. This is my plan anyway!

I purchased a low-end dual trace Tektronix scope with a recent calibration sticker on ebay for under $100. It's not the best scope in the world but for tube amp stuff it's fabulous! The circuit cards are simple and sparse- if I did manage to damage one I'd bet I could fix it with minimal effort.

I have a Heathkit scope that's destined for the parts bin- I don't want to source all the odd noval tubes to make it right again and I don't want to deal with all the circuit boards. The power transformer will be fabulous for a 100-150 watt amp using some KT88's though.

jamie

[Justin Thomas]

Hey there,

Just wanted to thank everyone for their input. It sounds to me like it'll be going into the parts category. After doing a bit of poking around, I'm interested in using at least the PT and chassis out of this thing. The only thing I'm concerned about is that CRT winding - I tried measuring, but my meter doesn't go that high. I did add up the heater currents of all the tubes in it, and got about 10 amps - so this PT can supply a total of 10 amps of heater current, doesn't matter what kinds of tubes as long as they're all 6 volt heaters? I figure I could use the other windings for a whole other amp project, as rectifier diodes are cheap and plentiful...I'm thinking two low-power amps using really oddball tubes on the same chassis, and if something good comes out, hooray! I am learning it's much easier to replace and repair an established design than to turn something into something else...

I'm thinking I will end up going for a used scope elsewhere; I'll check around town to see if anyone sells 'em locally. Get something a little newer and not needing work.
Justin

[bob p]

a decent quality SS scope to get you by shouldn't be at all expensive. they're all over ebay. i bought a solid state hitachi dual trace scope on ebay for all of $40. i had a friend do the pickup for me. total cost: $40.

each of my two signal generators ended up costing more than my scope. i used the 3 of them to draw that lissajous figure on the left.