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Kb2rgz
New member
Username: Kb2rgz

Post Number: 6
Registered: 11-2009
Posted on Saturday, September 04, 2010 - 8:42 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Hi I have A Ranger 2950 that I use on 10 meters on sideband, I run a Texas Star DX 350 HDV I am running to an IMAX 2000 60amp supply. Everything works perfect. Base setup.
When I conect the Cobra 29 LTD up Switch the amp to am And test the red light on the radio lights for antenna warning. I have a perfect match on all chanels on Radio swr and Dosy meter, The radio swr is high with the amp on. I adjusted the output to 4 watts and have foward swing, The radio came set at 3.5w but the swing was backwards with the amp. I dont plan on useing this radio above 4 watts talking local but I am still wondering the cause.The radio swr is high but the dosy swr after the amp is ok.
Thanks for your input.
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Big_mac
Junior Member
Username: Big_mac

Post Number: 17
Registered: 11-2011
Posted on Thursday, November 24, 2011 - 10:25 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Maybe Antenna wet, could had moisture in it
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Moonraker
Intermediate Member
Username: Moonraker

Post Number: 299
Registered: 3-2005


Posted on Friday, November 25, 2011 - 10:40 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Check the swr between the radio and amp. I would use the swr meter on the radio because if there is an impedance mismatch you will get a different reading when you switch jumpers around to install the meter. If you have a low swr (2 or less) the antenna warning light just needs to be adjusted (the adjustment pot is vr6). You can double chack with an external meter but don't be surprised if the reading is different.

Your tuning problem is in the amp and not the antenna. The variable power on the amp will change the input tuning when you adjust it. Lowering the dead key on the radio to 2 watts and turning up the variable might make a difference.

How much is the amp dead keying? I would say 60-75 watt dead key is about right. Set the dead key to 1/4 of your max pep swing. As you increase the dead key you start to loose your forward swing and it will swing backward if you push it really hard. The amp just runs out of head room.

Did you use a different jumper length between the amp and radio when you switch ed to the 29? If you have an impedance mismatch between the radio and amp different coax lengths can either hide the problem or make it worse.
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Gator44
Member
Username: Gator44

Post Number: 67
Registered: 1-2007
Posted on Tuesday, March 13, 2012 - 5:36 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

maybe a bad jumper???

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