[time-nuts] Problem with HP 83623A 20 GHz sweep generator stepping up/down 100 Hz when not wanted.

Scott McGrath scmcgrath at gmail.com
Fri Dec 23 06:43:21 EST 2016

I think case #1 tells you that the frequency step is not occurring on the sweeper as both The source and receiver are locked to GPS and no trace of the step effect is seen 

 I would be much more inclined to think that the transverter is encountering some type of power supply related artifact.

As to the tuned receiver mode yes it's VERY poorly documented but I use it in conjunction with an Anechoic chamber to characterize antennas

> On Dec 22, 2016, at 5:45 PM, Dr. David Kirkby (Kirkby Microwave Ltd) <drkirkby at kirkbymicrowave.co.uk> wrote:
>> On 22 December 2016 at 02:54, Scott McGrath <scmcgrath at gmail.com> wrote:
>> Can you use the VNA as a receiver? And determine whether the 100Hz shift
>> is also seen on the VNA
> The VNA has what's called "tuned receiver" mode, but it is very poorly
> documented - or at least I've never seen it well documented.
> I tried a few different things.
> 1) Put the sweep generator into the VNA using tuned-receiver mode. Both
> were locked to GPS. The signal generator appears in the middle of the
> screen, and whilst one can't say a lot about the quality, there's no doubt
> that the position of the peak never moves `100 Hz.
> 2) Put the signal generator into the spectrum analyzer. This does show some
> odd results sometimes, but I'm always a bit concerned that these might
> internally generated signals, as whatever source on connects to the SA, it
> brings up a lot of spurious signals. There's currently no preselector on
> this, although I do have one in a box.
> But there is some evidence that maybe the oscillator is moving. But I'm not
> 100% convinced.
> 3) Connected the source output of the VNA to the spectrum analyzer. The SA
> shows the source is far from clean - much poorer than the signal
> generator.  So I think I can conclude that the source in the VNA is quite
> poor, which is what I expected to be honest. There is not even a
> specification for phase noise on this.
> So any thoughts of mixing the VNA source with the signal generator will be
> a complete waste of time.
> I think I can conclude that attempting to use the VNA in any source of
> measurement or as a signal source will just not work.
> Dave
> <spectrum-analyzer-does-show-something-odd.jpg>
> <spikes.jpg>
> <vna-shows-no-obvious-issues.jpg>
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