[Repeater-Builder] SWR at Isolator-input

[rogeradio]

I'm trying to install a repeater and have encountered a puzzlement.   I re-tuned a Telewave dual-isolator down from 452.xxx to 443.55 MHz for installation on a new GE M-II 100W UHF repeater.   At the site, I connected the xmtr's coax cable to the the isolator's input (yes, it was the  Input port).    I connected the isolator's output to the duplexer's xmtr-side  port.  I used only RG-214 coax cable.  I put a 10-watt load resistor. on the LOAD port nearest the transmitter and a 100W load on the LOAD position next/nearest to the isolator's output.   Then I inserted a BIRD wattmeter between the Xmtr output coax and the isolator's INPUT port and keyed the transmitter, I read 110W fwd and 2W rev.  OK!   But after 45 seconds of continuous transmission, the reflected power had risen to 7.5 watts and was rising.   I unkeyed the xmtr.    I am puzzled.  I expected the isolator to behave constantly:  X watts fwd; and Y watts refl.  This variability I'm seeing makes me think that I have a changing impedance inside the isolator .  The 100 watt load was beginning to warm up in the 45 seconds duration of my test.  I swept the duplexer with my IFR to see if the rcv/xmt ports were labeled wrong.  Nothing unusual here .   I put the GE's transmitter direct to the antenna through the wattmeter and got 110W fwd and 1.5 watts reflected    What is going on with this isolator?   Should I be concerned?  and what do I do about it?.    I would like to have some suggestions  Yahoo! Groups Links To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/   To unsubscribe from this group, send an email to: [EMAIL PROTECTED]   Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.