Tektronix specifies bandwidth at the probe tip (1) and *not* oscilloscope bandwidth except in special cases.
If you use one of their 200 MHz oscilloscopes with the specified probe, the bandwidth at the probe tip (in the coaxial feedthrough test fixture) will be the oscilloscope bandwidth specification.
Sorry, but I read it the other way round. This well known document clearly states the obvious:
In general, the bandwidth and rise time interactions
between probes and oscilloscopes are complex. Because
of this complexity, most oscilloscope manufacturers
specify oscilloscope bandwidth and rise time to the
probe tip for specific probe models designed for use with
specific oscilloscopes.
Specific probe models, designed for specific scopes, will not have an isolated bandwidth specification, but a system specification, i.e. their bandwidth is always specified in conjunction with the scope they are designed for. This is an important difference to your interpretation. The fact that specific probes are not specified without the corresponding scope does not mean that the scope cannot have a bandwidth specification on its own without probe.
Consequently, I looked up the datasheets for TBS2000 and DPO/MSO2000 on
www.tek.com and they specify the bandwidth of their scopes just like any other manufacturer does. There is absolutely no hint that this specification includes or requires any probe (if this were actually the case, it
has to be stated in a datasheet!); furthermore, the datasheet doesn’t even specify the supplied standard probes.
For high impedance inputs with external or internal 50 ohm terminations, this breaks down at higher frequencies because the probe compensation includes corrections to the oscilloscopes input response which is where all of those old A and B oscilloscope probe versions came from. Now they are more likely to use disparate part numbers. Most users would never notice the difference but the oscilloscope is unlikely to meet its transient response specifications with the wrong probe unless the probe's high frequency compensation is adjusted. (2) At least some of the various smart probes handle this through digital calibration.
Nothing breaks down at higher frequencies. I’ve yet to come across a scope that wouldn’t meet its specifications when using a direct connection – but then again, I have not tested this on any Tek scope. Anyway, It would be really sad if Tek scopes would not meet their transient response specifications with direct coax connection but required some special probe for that.
We are talking about the SDS2000X here, which is a general purpose DSO/MSO where I have tested the top model with 300MHz specified bandwidth (
without probe). Of course we expect such a scope to have its 3dB bandwidth some 5-10% higher than specified when measured directly. In fact I was happy to see an actual 3dB bandwidth between 10.67% and 17.33% higher than specified, depending on the vertical gain setting (up to 100mV/div).
With the supplied SP2030A probes, the 3dB bandwidth expands by more than 50%, so there is indeed some massive frequency response correction going on. Many other probes from various manufacturers have been tested and none of them provided a comparable result, not even a fancy Keysight N2843A (500MHz) probe borrowed from an MSO-X3000A. An old Tektronix P3010 (100MHz) probe that belongs to some TPS2000 (one of these isolated channel scopes with no sample memory) performed not too bad overall, slightly lower bandwidth (still >400MHz -3dB), but better signal fidelity than the Keysight on the SDS2304X. Of course I’m convinced that these (and all other tested) probes work beautifully together with their associated scopes, just haven’t bothered to measure them all.
So I have been the one who has repeatedly warned people to not swap their supplied probes for “better” ones, because the probes need to be matched with the input characteristic of the specific scope. It is not only bandwidth and rise time, but also signal fidelity which is usually close to an optimum with the original probes and might degrade significantly with a random one, even if it has a much higher bandwidth specification.
The probes with separate HF-adjust should be more universal in theory, but my tests with one of these were a rather mixed bag and not really convincing overall.
Finally it should be mentioned that the practical value of a passive high impedance probe at 450MHz (this is the bandwidth I get with my SDS2304X and the supplied SP2030A probes) is rather doubtful. It works well when probing a low impedance (25 ohms) source, but if we have such a low source impedance we could as well use an L-attenuator to match a coax cable or build a Z0-probe. With an input capacitance around 10pF or even higher, there are not many nodes carrying signals at several hundred MHz that could be connected to a high impedance probe without throwing the circuit completely off track.
For the direct connection bandwidth test, I’ve mentioned the vertical gain settings up to 100mV/div so far (actually it applies up to 148mV/div). Above that, the first attenuator kicks in; this is also why the frequency response changes significantly at 200mV/div and 500mV/div. This attenuator is also designed to correct the frequency response of the scope (of course, it has to), and we see even higher 3dB bandwidth limits.
The Tektronix SG503 leveled oscillator is suppose to be within 3% up to 250 MHz or about +/-0.25dB which is why I wondered. The unleveled sources I have seen up to now were at least twice as bad. Testing showed that SG503s are usually half as bad as their specification.
3% up to 250MHz sounds really good, but 250MHz just doesn’t get you very far nowadays, where even the cheapest entry level scopes might start at 200MHz (Siglent SDS1202X-E) with their 6dB bandwidth close to 300MHz.