[AMPS] Hold on - SWR meter placement

[measures]

>
>
>-----Original Message-----
>From: measures <measures@vcnet.com>
>To: Gilmer, Mike <mgilmer@gnlp.com>; 'AMPS'
><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. 

OK

>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. 

One must measure the min (null) and the max. v on the slotted line.  

> 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.
>
Arghh

later, Steve

-  Rich..., 805.386.3734, www.vcnet.com/measures.  


--
FAQ on WWW:               http://www.contesting.com/ampsfaq.html
Submissions:              amps@contesting.com
Administrative requests:  amps-REQUEST@contesting.com
Problems:                 owner-amps@contesting.com
Search:                   http://www.contesting.com/km9p/search.htm