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Author Topic: Measuring SWR on mobile dualbander w/external dupl  (Read 348 times)
KE4AQP
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Posts: 11




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« on: June 28, 2000, 04:10:54 PM »

I have a Kenwood 732A with 2 meter and 70cm coax outputs, which connect to a Diamond duplexor and then to my Larsen 2/70 via a single RG-58A/U coax feed.  When measuring and adjusting the  SWR and reflected power of my mobile antenna, should the SWR / Power meter between the rig and the duplexer or between the duplexer and the antenna?  My inclination is between the rig and the duplexer, but I would like another correcting or confirming opinion.

73 and thanks,

John
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KF7SN
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Posts: 31


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« Reply #1 on: June 28, 2000, 05:51:07 PM »

John you did not say weather your swr meter was a dualband meter or just for 2 meters. Try putting the meter between your ant. and duplexer. That should work. I have a duplexer also but I use a 2 meter amp. So I go from the TX to amp to meter (Note my meter is a dualband meter) to my ant. In the case I use the duplexer I then but the meter after the duplexer. I have been haming for 20 years and am a retired electronic tec. 73 Geary KF7SN (Email: KF7SN@arrl.net)
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KE4AQP
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Posts: 11




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« Reply #2 on: June 28, 2000, 07:59:30 PM »

Oops.  Sorry about that Geary.  The SWR meter I am using is a Yaesu YS-500 with 144Mhz - 512 Mhz coverage.  I guess I am just confused as to whether for the purposes of SWR measurement the duplexor should be treated as part of the antenna system (and thus its reactance taken into account by the meter) or treated as part of the "rig".
Thanks, John.
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KB0CY
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Posts: 12




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« Reply #3 on: July 06, 2001, 01:31:26 AM »

In response to:
"I guess I am just confused as to whether for the purposes of SWR measurement the duplexor should be treated as part of the antenna system (and thus its reactance taken into account by the meter) or treated as part of the "rig"."

 Perhaps it would help if you think of the SWR meter
 as measuring the match at the point that the meter
 is placed in line. Although we'd like to think that
 the SWR is constant in the antenna system, in reality
 the SWR meter is telling us what it "sees" at the
 place the meter is inserted into the system.

 So, if you are concerned about the actual SWR of
 the antenna, the SWR meter should be inserted
 in the system near the antenna. If you are concerned
 about the match between the rig and the duplexor,
 then insert the SWR meter there.

 You are probably concerned about both, so you
 may end up measuring both.
   Bob KB0CY

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