[time-nuts] VNA design

paul swed paulswedb at gmail.com
Tue Jun 3 20:31:39 UTC 2014


My bad the 8757 is only a scalar not a vna like the 8410 and 8505. Thought
I went astray and had to go look after you mentioned the options.
Regards
Paul.
WB8TSL


On Tue, Jun 3, 2014 at 3:32 PM, Dr. David Kirkby <drkirkby at gmail.com> wrote:

> On 3 June 2014 19:22, paul swed <paulswedb at gmail.com> wrote:
> > Great comment by Dave on the fact that someone
> > will give out some of the old options. Now I have to figure out what on
> > earth that might actually mean.
> > Regards
> > Paul
> > WB8TSL
>
> There are a few options for those VNAs. These are basically generic,
> but check your manual for more details.
>
> 1) Option 006, on an 8753B or later, allows the instrument to work to
> 6 GHz. It basically lets the receiver tune to 6 GHz, but the internal
> source still only goes to 3 GHz. So you need an S-parameter test set
> with a doubler to get to 6 GHz. But there is no harm in having the
> option, irrespective of whether you have a 6 GHz test set.
>
> 2) Option 010 is the time domain. It converts the frequency domain
> data to the time domain via an inverse FFT. Then you can put a "gate"
> around some stuff in the time domain and transform that back to the
> frequency domain.
>
> A nice option to have, and very expensive on new instruments.
>
> 3) Option 002 allow the instrument to work on harmonics. I'm not sure
> how useful that actually is - I think it was mainly for internal use
> at HP, and is not of great use, but if you can get the option, you
> might as well.
>
> 4) Old 8720 series instruments had a tuning step of 100 kHz. There is
> an option to make that 1 Hz. How the **** HP got away with selling a
> VNA where the step size was 100 kHz I will never know, but they did.
>
> There are other options for the instruments - the most time-nut
> related is the high stability oscillator. That is option 1D5 on my
> instrument (8720D). I don't know how easy it is to add the hardware to
> an 8753 - I suspect it is just one of the standard 10811A or similar
> oscillators. If you do that, it would seem sensible to get the
> instrument to report it has the option, even though it wont actually
> effect the performance. It would affect the resale value, and would
> mean Agilent would calibrate it properly if sent it for cal.
>
> When my 8720D was sent it for calibration, the accuracy of both the
> standard and the high stability oscillator was checked. Both were in
> spec. I suspect they would not check the high stability one unless the
> instrument reported it had that option fitted.
>
>
> BTW, Agilent will still calibrate 8753s, and when I got my 8720D done,
> it was not that expensive. I guess it is all relative, but the 8720D
> is quite an expensive instrument, and I use it professionally, so it
> is worth getting calibrated - unlike 99% of the other stuff I have.
>
> Dave
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