Thanks for the response, turned out to be a duff tube, what a pita that is to swap to test!
Initially though the focus at end stop was caused by misadjustment of the edge focus internally.
---In TekScopes@yahoogroups.com, <chris@...> wrote :
I've got four 24xx scopes, and on three of them the optimum focus point is
roughly in the middle of the focus knob's travel. One one of them (a 2465)
the best focus is with the focus knob turned all the way counter-clockwise.
In that position the display is as sharp as the other scopes, so I've never
looked in to why it is the way it is, but something odd must be going on.
This probably isn't a lot of help to you but it shows that oddness with the
focus control is not unknown.
On Fri, Mar 11, 2016 at 1:40 AM, chipbee40@... mailto:chipbee40@... [TekScopes] <
TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com> wrote:
> Hi, All you 24xx experts.
> Just had a customer bring a 2465A in. Has a 2016 expiry cal cert from a
> reputable source. Customer complaint is poor focus. Sure was. Focus at end
> stop. I'm limited to what I can adjust because it may get returned but
> opening it up edge focus was also at end stop. (customer twiddling?) Power
> supply ripple and volts all good, well within spec, very clean scope, How
> can you check hours use on this?.
> So I did the focus and astig adjustments and got a reasonable display but
> I'm not convinced this is the best a 300Mhz scope can do.
> So how good is this scope display supposed to be? I don't get many 24xx
> scopes, the last 2445 was a couple of years back and it didn't stand out as
> particularly blurry. I must admit I'm comparing to my Fluke PM3394B which
> is ultra sharp but this is on par with a 2230 or slightly worse. Text and
> traces are not as sharp as I would expect, not out of focus but just not
> sharp. Also I seem to have to continually correct the focus depending on
> signal or display option. doesn't seem right to me.
> I checked the resistors in the focus circuit, all bang on.
> Do the tubes soften on these? Anything I should check before I tell the
> guy this is as good as he can expect?