-----Original Message-----
From: measures <measures@vcnet.com>
To: Gilmer, Mike <mgilmer@gnlp.com>; 'AMPS'
<amps@contesting.com>
To: <amps@contesting.com>
Date: 08 October 1999 23:41
Subject: RE: [AMPS] Hold on - SWR meter placement
>
>On Friday, October 08, 1999 4:36 PM, measures
[SMTP:measures@vcnet.com]
>wrote:
>> ? I am aware of no textbook that says moving an SWR meter
along a
>> mismatched transmission line will make no difference in
the reading. The
>> 93-ohm halfwave line in the Quiz was just such a case.
The measured SWR
>> varied all over the place.
>>
>
>Are we sliding a SWR meter or a voltmeter along the slotted
line?
>
? volt
- Rich..., 805.386.3734, www.vcnet.com/measures.
If the VSWR is not 1:1 the voltage on the line will vary
with position along the line. The VSWR is related to the max
and min values that you find (quarter wave apart so your
line might have to be very long at hf), it is not simply the
voltage that you measure at any particular point. You can
work out the reactive component of the load from the
position of the peaks and nulls (nulls tend to be sharper to
measure than peaks).
Quality slotted lines offer the ultimate in precision but
are inconvenient to use. A local calibration lab was closing
about a year ago, their Rohde&Schwarz reference slotted line
setup was up for sale at about $40k.
Steve
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