[TowerTalk] Coax Switch Isolation

[don tyrrell]

Zoli,
Your set up is perfect and is indeed the professional way to do it. No
arguments on that. I don't know why the differences on that, unless
something happened with that switch and we made it incorrectly. Sometimes
it's hard to know. Thank you for the details---I see nothing wrong at all
with what you did,
Don,  W8AD, Alpha Delta
Don Tyrrell at d.r.tyrrell@worldnet.att.net
----- Original Message -----
From: <z.pitman@libertel.nl>
To: <d.r.tyrrell@worldnet.att.net>
Sent: Thursday, June 15, 2000 12:02 AM
Subject: RE: [TowerTalk] Coax Switch Isolation


> Hi Don,
>
> It was a nice try but...
>
> I was the one who measured one of your units. It was a
"right-off-the-shelf"
> unit, bought by my father one year ago and kept in box since then.
>
> Measurement setup:
>
> 1, Hewlett-Packard HP8591E Analyzer (9 kHz-1.8 GHz, cal.date: 10/99)
> 2, Suhner RG-214U cables with Suhner N-connectors (checked 10/99)
> 3, Suhner N/PL-259 converters.
> 4, Suhner 50 ohm terminators (up to 1 GHz)
>
> The HP unit source was connected to the TX-port of the switch, and the
> spectrum analyzer was connected to one of the ports. The other ports were
> terminated with 50 ohms. The isolation was measured from 1.5 to 30 MHz.
The
> measured isolation varied between 26.5 and 35 dB.
>
> > They say the most common reasons for comparative test
> > errors in non lab environments are: A. Improper use of, or
> > faulty jumper cable/connector assemblies.
>
> The lab's cables were checked by Suhner in Oct 99. The reference level was
> set with all the cables included. I used a SO-258/SO-258 barrel connector
in
> the place of the switch, when setting the reference. The cables and
> connectors are not faulty.
>
> > B. Improper or faulty test loads.
> > These must be exactly R50 plus J ZERO loads.
>
> See above. They are resistive 50 ohms. (BTW, who on the Earth has 50+j0
> antennas in his shack ?)
>
> > C. In the case of the DELTA-4 family, the
> > case must be hard grounded to a proper ground system since
>
> The lab where I measured this unit is an official lab used for GSM and PCS
> (up to 2 GHz) measurements and verifications. It has a lab standard
> grounding and static protection.
>
> It sounds fair enough for me.
>
>
> 73 de Zoli HA1AG
>


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