[Uram-rejections] An analogue VNWA?

Fri Feb 26 13:44:42 GMT 2016

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============================================ Full text of your message follows
> From webstump at chiark.greenend.org.uk Fri Feb 26 13:44:42 2016
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> From: Brian Reay <no.sp at m.com>
> Newsgroups: uk.radio.amateur.moderated,uk.net.news.moderation
> Subject: Re: An analogue VNWA?
> Date: Fri, 26 Feb 2016 13:44:37 +0000
> Organization: A noiseless patient Spider
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> On 26/02/16 12:46, Roger Hayter wrote:
> > Brian Reay <no.sp at m.com> wrote:
> >
> >> gareth G4SDW GQRP #3339 <no.spam at thank.you.invalid> wrote:
> >>> Firstly, I now admit defeat and will post to UKRAM but with a fuller moniker
> >>> to counteract atempts at forgery.
> >>>
> >>> Were I to think about an analogue version of the VNWA, it
> >>> seems that what I would need is a swept oscillator with the sweeping
> >>> sawtooth  feeding the x-input of an oscilloscope, the rectified reflected
> >>> power indication from a VSWR bridge to feed the first Y input, and
> >>> then a phase detector acting on the oscillator output and the UNrectified
> >>> reflected power indication to drive the second Y input of the
> >>> oscillsoscope, thus saving several Ã¯âˆÂ£100.
> >>>
> >>> Any opinions on that idea?
> >>
> >>
> >> What do you think your display would look like? Or, more exactly, how would
> >> you interpret it.
> >>
> >> I am assuming you aim is to use to S parameters as they are easy to measure
> >> and you seem to be trying to measure some of them, or more exactly perhaps
> >> working towards finding them. However, not only is a method of reading S22
> >> missing, it is a key parameter.
> >>
> >> In fact, I think you can, at best, get an estimate of 2 of the 4 S
> >> parameters, S11, S21. Not really enough to define a network - although
> >> perhaps useful in some basic applications.
> >
> > Other things being equal, one can normally do this by simply reversing
> > the DUT.
> >
> >
> >>
> >> Of course, I may have overlooked something, if so please explain exactly
> >> what it is- ie who you are finding the missing S parameters or, if you are
> >> using an entirely different method which just resembles the S parameter
> >> method in part, what it is and the theory behind it.
> >>
> >>
> >>
> >>
> >>>
> >>> Also, before days of (relatively) easily available spectrum analysers, the
> >>> RF signal genny with a wobbulator was a well-known approach, but any
> >>> mention of such a thing is only to be found in old publications.
> >>>
> >>
> >> That doesn't mean the technique isn't used. Such techniques live on,
> >> propagated by those in our hobby who attend clubs, teach newcomers, given
> >> lectures, attend events like the RSGB convention, take part in groups like
> >> RSGBTech,...... Things change, for good or ill, books are largely being
> >> replaced by other means of spreading and sharing knowledge. We can lament
> >> such change or make it work to our advantage.
> >
> > RSGBTech is a closed Yahoo group which quite a few people have not been
> > allowed to join or read,
> 
> Please do not abuse your position as moderator to spread malicious 
> information.
> 
> Do you have any evidence to support your, incorrect and malicious claim 
> that 'quite a few have not been allowed to join'.
> 
> 
> >and not all of us can get to clubs.
> 
> But many can.
> 
>   Do you
> > have any actual information on the subject that you could share with the
> > rest of us?
> >
> >
> >
> 
> Clearly you didn't read my post, you were too focused on abusing your 
> role as moderator.
> 
> 
> 
> 
> 
> 
> 
> 
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