I just noted that my old 465 scope is running circles around my 2235A for internal
triggering stability. I never liked that new plastic POS compared to my old reliable 465.

Are there any common issues with the 2235A triggering circuit: parts that fail or alignment,
that might be applicable here? It will sync up, but it is very touchy and not stable. The
465 locks in like a rock. Pretty sure all the controls are set up correctly, double checked
that first

Pete

Where did all the Tek scope guys go?? I reseated some of the cable connectors and that seems
to have corrected a lot of the problems. I still feel the 465 has a better triggered sweep, and that
bothers me.

Pete

I never used a 2235, so I can't compare the two, but the 465/75 triggers were, I thought, pretty good. The Trigger Specs for the two models are very similar. Are you talking about a significant measurable difference or more nuance? Funny, even in the "newer" equipment its still the mechanical stuff still causes problems.

If you want experts, The Tek Yahoo board, as you know, is the place to go.

Mike

I was trying to lock onto a modulation waveform from a signal generator. It was
extremely difficult to get the scope to lock on the pattern. It would sweep, but not
lock and when I could get it to lock the pattern had a lot of jitter. The 465 locked
right up and the triggering was rock solid over a wide range. Right now it seems
to working as it should. And it figures that this is the only item on the bench that
I don't have the service manuals for!!

We had a few Tek guys on here, but they've noticeably absent.

Pete

Is "HF reject" available on the trigger qualifier?

HF and LF Reject. None of which did much when it was acting up.

A little clarification on my earlier post.

When I said "the two models" I was referring to 465/75, and, the 2235.

FWIW, The Ops manual is on BAMA and includes the specs sheet.

Try triggering the scope externally off of the modulation signal. (400 Hz?)

Charlie

Fixed for now, but that was the next step. Without the manual or a flow chart it is kind of
hard to do component level repairs--but I see vendors selling complete boards pretty cheaply.

Pete

I dunno if it helps much...

I've a 2246, AFAICT, roughly the same generation of 'scope, but I don't know how much is similar between the two.

I didn't have much problem getting a stable display feeding an 1.2Mhz signal AM modulated at 400 Hz & 1Khz from the 8640b straight through (terminated) to the scope.

Little more difficult when I 100% modulated the signal, but still not difficult.

The Holdoff control was more useful than the Trigger level getting it at 100% modulation.

<shrug> Like I said, don't know if its much help.

If you want to chase down a service manual, Dave over at ArtekMedia looked to have a scan available, I've had good dealings with him.

David

The scope TRIG LEVEL control doesn't really know if the R.F. carrier is modulated or not. To "freeze" the modulated carrier, to display a stationary modulated display, trigger off of the modulating signal.

Charlie