[time-nuts] OT: Power level reference

[David C. Partridge]

>In fact, on the Tek 7704 or 7704A (I forget which) there were "No Cost"
>options of maximally flat frequency response OR best pulse response. OR! 

I think you may find the option was best pulse response OR an increased 3dB
frequency of 275 MHz.   The difference is just an matter of adjusting the
compensation in the vertical amp.   The best pulse response in terms of
least overshoot etc, also gives a flatter response in the pass band (which
it should as this is effectively adjusting to give a pure Bessel response).
The higher 3dB frequency version gave considerable overshoot on the pulse
response, and a "bumpier" pass band.

I was quite surprised to find quite HOW bumpy the pass band can be the first
time I did a check on my 7904 using an SG504. 

Dave

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of J. Forster
Sent: 02 December 2009 01:31
To: Mike S
Cc: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] OT: Power level reference

I do. Very well, in fact.  Unless you have swept a scope with a very well
leveled sine generator, you are only guessing it is flat.

That's WHY Tektronix sells BOTH fast rise Pulse Generators and Leveled Sine
Generators.

In fact, on the Tek 7704 or 7704A (I forget which) there were "No Cost"
options of maximally flat frequency response OR best pulse response. OR!

-John

================


> At 07:00 PM 12/1/2009, J. Forster wrote...
>>Scopes tend to have non-flat frequency response. I'd consider a 
>>precision load and something like an HP 3400A True RMS meter for up to 
>>a hunderd MHz or so.
>
> You have to know your equipment. I have a Tek 485 350 MHz analog 
> scope, so I'm confident it's flat into VHF (at least beyond 100 MHz). 
> I've verified it exceeds the 350 MHz spec (i.e. < 3 db down @ 350 MHz) 
> with a tunnel diode pulser.
>
>
>



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