开云体育

Usually a delaying timebase like the 7B85 (7B71 in your case) would be used in
the left horizontal slot and a delayed timebase like the 7B80 (or 7B53A in your
case) would be used in the right horizontal slot. As far as I know, *any*
timebase can operate as a delayed timebase. The 7B87 is just a special case of
a delayed timebase intended to replace the 7B80 and operate in the 7854. It
allows capturing pretrigger events which is a typical use for digital storage
oscilloscopes and unique within the 7000 series although I have not gotten must
use out of it since I have other DSOs for that type of thing.

I think the most significant difference between the 7B85 and 7B71 is that the
former displays the delay time on the readout and supports dual delayed
operation. They both have peak to peak triggering which is something I wish the
7B53A had.

I actually bought the 7904 *for* the 7CT1N but despite the UPS shipping damage,
I have grown to really like the mainframe if only because of its silent
operation (no fan) and bright and crisp CRT. The full set of plug-ins was just
icing on the cake.

It looks like the older 7854 uses the custom designed Tektronix fan found in the
other 7000 series. It should be nearly silent so if it is making noise, I would
assume that the bearings are either worn out or in need adjustment and oiling.
There was a recent discussion about this on the list.

On Fri, 24 Jan 2014 10:20:27 -0500, you wrote:

David,

This is going to be a whole new experience for me, not just because of
the complexity of the waveform portion of the scope. I've only had
three-bay scopes up to this point, so it will be interesting to see how
being able to use two time bases can be mixed into the equation.

The 7B71 is also a little different than what I'm used to using, so I
really need to dig into the books. Don't have a 7B87 as of yet, though
I do think I have a 7B85 in my stash of stuff.

And on the 7904 with the 7CT1N you got? Okay, "YOU SUCK!" ;-)

Mark

On 01/24/2014 10:05 AM, David wrote:

One thing I always found odd is that the 400 MHz 78xx series existed when the
500 MHz 7904 predates them by a couple years. There is a difference in the
trigger channel switch chain which might explain this but I suspect it was for
yield or because of grading.

You definitely got a great deal. I think the best I have done is a K212
instrument cart for $0.99. I got my 7904 with a full set of plug-ins including
a 7CT1N for about what you paid.

I think you can use the 7B71 to delay the 7B53A which will give you the
alternate sweep mode of operation that the 7B53A by itself lacks. I think the
7B71 will also work with the 7B87 so you do not need a 7B85 if you want to
capture pretrigger events.

On Fri, 24 Jan 2014 05:55:08 -0500, you wrote:

Well, the 7854 arrived in yesterday in a BIG brown box delivered by a
big brown truck. No visible damage to the BIG brown box, so I excitedly
slit open the packing tape. Scope was packed well with decent
styrofoam, and was shrink-wrapped before being put in the packing.

Got it out of the box, blew off the little styro balls from the packing,
opened the scope case and saw the inside of the scope was really, really
clean. This scope, both from the outside and from the inside of the
case looks like it was just taken off the shelf at Tektronix.

Pulled the 7603 off the cart, placed the 7854 in it's place. Pulled the
7D15 and 7B71 out of the plugin slots and fired it up. Guess it hadn't
been run in a while as the fan was quite noisy when I first turned it
on, but the fan eventually settled down into a nice murmur.

Self test completed successfully, and I proceeded to start fiddling with
the front panel controls. Shut it down and popped in a couple of known
working 7B53's, a 7A18 in the left vertical slot and a 7A22 in the right
vertical slot. Powered it back up, and fiddled some more with the front
panel controls to get a feel for the switchology.

I hooked a short BNC cable to the CAL port and to the 7A18. Very, very
nice trace. Same for the 7A22.

Shut it down, pulled one of the 7B53's and popped in the 7B71 that came
with it. Got to do some reading on this time base, but it too worked sweet!

Now for the real gloat...

I bought the 7854, which came with the 7D15 and 7B71 for... $110.

I just purchased the waveform calculator from the Bay of E this morning
- $45 ;-)

I'm a terribly happy proud new owner of a working 7854! Woo hoo!!!!!!!

Mark

Thanks guys!

On Fri, Jan 24, 2014 at 5:21 PM, Michael A. Terrell
<mike.terrell@...> wrote:

cheater00 . wrote:

On Fri, Jan 24, 2014 at 2:16 PM, Mark Wendt <mark.wendt@...>
wrote:

On 01/24/2014 07:54 AM, Craig Sawyers wrote:

I bought the 7854, which came with the 7D15 and 7B71 for... $110.

I just purchased the waveform calculator from the Bay of E this

morning

- $45 ;-)

That sir is a real bargain!

Almost as good as my AA501 for $14 or 7L5 with tracking gen in a

scope for

???70 (say $100) :-)

Craig

Heck yeah! I'll take them kinda bargains every day of the week!

You stole both that AA501 and that 7L5. ;-)

I'm on a metal working forum where when someone posts his gloats like
that, it's obligatory for the rest of the forum population to post in
reply - "YOU SUCK!" ;-)

Hi Mark,
may I ask what forum that is? I didn't know of any good metal working
forums.

I use the news:rec.crafts.metalworking Usenet newsgroup, but there are
others.

And THAT is why I love this list.

D.