Hi, everybody.
So at some point I will take the plunge into vacuum tube audio, and according to George Lydeck on this group, the Tek 535A is the best scope ever for tube audio work.  Now, I figured out that the letter series and 1- series plug-ins, although not all of them, are the ones to plug into this mainframe.  I have that stuff on my Test Equipment Wishlist already.
OTOH, plugging directly into scope or plug-in inputs (assumed BNC, since I don't really want to go down the rabbit hole of UHF connectors) is probably not going to be productive, so I will need some probes.  Type N, SMA, 3.5 mm, BNC, and TNC are quite enough variety in my garage lab, thank you very much.

Try as I might, on TekWiki and the Internet at large, I cannot find anything specifically saying which Tek probes are appropriate for a vacuum tube scope such as the 535A.  Maybe this is tribal knowledge?  AFAIK, I have not used a scope with more than 1 tube, the CRT, (I was born in 1965, approaching 60 years old early in 2025), so the world was mostly solid-state by the time I was old enough to be playing around with scopes.  Come to think of it, all 5 of my current scopes have CRTs, and I don't think I've owned one yet with an LCD screen.  I'm in the 'tween generation, I guess.
Any recommendations for probes for a 535A?  Plug-ins also would be a good idea to know for the wishlist.
Thanks a bunch!
Jim FordLaguna Hills, California, USA

Jim
The Tek catalog from March 1967 is what you need. I've had one for years and its one of the best single references for the 500 series stuff that you will find. I see its available on Tekwiki - lots of data on appropriate probes and plugins.
DaveB, NZ

The handbook for the scope should tell you its input impedance which will tell you what probes it can use. Typical scopes have 1 megohm input but not all. Probes can provide voltage range extension which is accompianed with increased impedance, i.e. a 10X probe will give you 10 meg impedance. Probes usually also have some means of compensating for capacitance, usually an adjustment on the probe to optimise its square wave response. Beside scope specs also see the catalogs for probe specs.
Now, if you are going to explore vacuum tube amplifiers you absolutely need the "Radiotron Designer's Handbook" 4th edition. Available several places on the web for example:
<http://www.tubebooks.org/Books/intro_RDH4.pdf>
Books on this site are very well scanned and complete. They are free.
Actual hard copies are still available, do a web search. Personally, being quite old fashioned I prefer hard copy actual books but must settle for electronic versions where the originals are not available or are too expensive.
Earlier editions of the Radiotron are of historical and some practical insterest, the 3rd edition is available at the same site:
<http://www.tubebooks.org/Books/intro_RDH3.pdf>
There will never be another book like the 4th edition, an excellent compilation of audio design at about the end of the vacuum tube period.
BTW, I also have the original Australian edition (in hard copy) and the American edition has everything and is excellently reproduced so there is no advantage to searching out an original.
I bought a 4th when they first came out and wore it out. I have since gotten two used ones beside the PDF version.
Lots of other tube audio books at Tubebooks.org
I wonder why the Tek 535A is considered so good for audio?

--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998

Hi Jim. Always glad to encounter someone using tube scopes in this day and age. I design and troubleshoot with tube scopes as well, although I often reach for the 2465A. Now it would be hard to find a Tek scope that could not be used for audio work. My personal preference is for the 502 or 504. The 504 is cheap, nice and portable, and offers adequate bandwidth. There is no fan so they are very quiet. On the downside they of course are single channel. The two channels of the CA are often very useful. The 530 series, the 531 and 535 both are good scopes for low frequency work, having a 15 MHZ bandwidth. However they do constitute a lot of scope for the application. They are big, heavy to move around, and noisy. They both are fairly complex, especially the 535 with delayed sweep, which I did not find very useful but it is there if you need it. It is tricky to find one that doesn’t have its problems, especially considering the age. If something goes wrong fixing a problem can be tricky. Also getting one shipped without damage can be a challenge. But with say a CA plugin they are a fine instrument. They originally came with a 6006 10X probe, which I use with most of my scopes. I have a lot of parts for these scopes, so if you do get one let me know if you need something. Best regards.