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Date: Wed, 19 Nov 2008 19:26:12 +0000 (GMT)
From: ALAN MELIA <alan.melia@btinternet.com>
To: rsgb_lf_group@blacksheep.org
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Subject: Re: LF: More on Admittance
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Hi Peter I think it more due to the fact that commercial bridges and meters=20=
really want to cover the widest range. There is obviously a problem with ser=
ial connected reactances when one is very much larger than the other. Then t=
he nulls on bridges become shallow and ill defined. If you use a parallel ar=
rangement this is not a problem. For most Amateur aerial cases you can get a=
way with serial connection because there is not the need for the wide range=20=
needed for laboratory equipment.....10^3 compared with maybe 10^6.

Alan G3NYK




--- On Wed, 19/11/08, Peter Dodd <g3ldo@ukonline.co.uk> wrote:

> From: Peter Dodd <g3ldo@ukonline.co.uk>
> Subject: LF: More on Admittance
> To: rsgb_lf_group@blacksheep.org
> Date: Wednesday, 19 November, 2008, 6:55 PM
> Many thanks to those who responded to my question regarding
> an=20
> Admittance to Impedance converter.
> I have a further question. Since most of the measurements
> we make on=20
> antennas and transmission line require the answer in term
> of impedance=20
> why are there so many commercial instruments calibrated in
> units of=20
> Admittance, particularly at VHF and UHF. I suspect that it
> is because it=20
> is easier to make accurate variable bridge standards if
> they use a=20
> parallel arrangement; is this true
> Regards
>=20
> Peter, G3LDO
>=20
>=20
> > The best program (as far as I am concerned) is called
> Z-Y Converter,=20
> > which was sent to me by Rik Strobbe.
> > It came direct because it gave the reflector
> indigestion although it=20
> > is only 160KB.
> > I was given a General Radio 1602-B Admittance Meter as
> a pre Christmas=20
> > present, which is calibrated in millimhos, which I
> guess is the same=20
> > as millisiemens.