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Testing Circulator / Isolator - RF Cafe Forums
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Lamini
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Post subject: Testing Circulator / Isolator
Posted: Fri May 11, 2007 6:03 pm
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Joined: Fri May 11, 2007
5:48 pm Posts: 3 |
Greetings everyone. Ive not new to here
as I come here every time I could use some help
and use the search feature mostly for antennas/vswr/smithcharts.
However, I have not found anything on testing Circulators
and Isolators. I have searched here and the net
with very little luck, i believe wikipedia had the
most info. Not that theory of operation on these
items wouldnt hurt me, I am mostly searching on
how to test them. Well, if I knew how they operated
then I would know how to test them. However, after
looking at the spec sheets of circulators/isolators
on the net, are they tested by insertion loss?
I have a Motorola R2670 easily available,
will this do the job? Its your basic comm test set
(for those that dont know), and more. Im not sure
on how to test a circulator (ie will this frequency
pass with very little amount of reflection?). Im
guessing I would use the Duplex function (generate
Freq on RF IN/OUT while monitoring Freq on ANT port
vs using Tracking Generator (?). THe Freq range
supported by the test set is applicable to what
I will be working on (make sure the circulator works
/ passes Freq with very little loss). Thank
you ahead of time. meanwhile i'll be playing with
the test set.
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Lamini |
Post subject:
Posted: Fri May 11, 2007 6:12 pm
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Joined: Fri May 11, 2007
5:48 pm Posts: 3 |
learned some info... environment is a radio
with < 200Watts out to antenna (VHF range). all
i gotta do is verify circulator/isolator work, was
told a double circulator was in place... whatever
that is
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RFTEJerry |
Post subject:
Posted: Mon May 14, 2007 10:14 am
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Captain |
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Joined: Thu Apr 13, 2006
9:53 am Posts: 17 Location: Florida
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Hello Lamini, An isolator is nothing more than
a circulator with the "final" port terminated in
a "perfect" 50 ohm load (or whatever the characteristic
impedance is).The purpose of these devices is to
direct RF energy in only one direction thus protecting
the device connected to one port from reflections
from another port "downstream". Both of these devices
are tested for 1) insertion loss 2) isolation between
ports and 3) VSWR. You can use a VNA or a coupler/PM/Spectrum
Analyzer to make the measurements. You don't indicated
whether these are stand alone componets to be tested
before insertion into a system or as part of a "circuit".
I'll assume stand alone. Insertion loss can be tested
by simply measuring the power into the device and
the power out. The difference is IL. Isolation can
be measured by applying power into device, using
a coupler on output port 1, terminate output port
2 and measure the feflected power from port 2 on
port 1. Continue around the circulator until all
ports are tested. VSWR is measured by measuring
the reflected power from the port of interest using
a VNA or a coupler and PM or spectrum analyzer.
I have always had good luck in contacting manufactures
of components I have used and asking them what and
how they test them. Good luck, RFTEjerry
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Lamini |
Post subject:
Posted: Thu May 24, 2007 12:02 pm
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Joined: Fri May 11, 2007
5:48 pm Posts: 3 |
I forgot to post my results from last week. I arrived
to the test location and everything happened naturally.
Was your basic Insertion Loss measurement;
0dBm in port 1 = 0dBm into port 2. 0dBm into
port 2 to port 1 nothing = everything good. I used
the Motorola/General Dynamics R2670 Communications
Test Analyzer in Duplex mode to transmit/receive
as neccessary with no problems.
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Posted 11/12/2012
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