Finding that good ground

turn the mic gain back to 12:00 and go from there
You sure its a 43/400? if so how?

If that radio is only doing 200 pep it isnt a 43/400
What you have is a 43/300, huge difference tween the two
regarding pep wattage.

 

First, do not continue to use the radio until the standing wave ratio [SWR]reading is down below 3.0 using an external SWR meter.
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A reading of 3.0 or higher indicates a connection problem. Continued use of the radio can damage the power transistors. That can leave you with a radio that has a quarter mile of range or less. And that is quite expensive to repair or replace.
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With a multimeter [volt/ohm meter] on the lowest scale, check the resistance between the antenna mount and the door where the door is connected to the upper door hinge. It should read zero. If not, run a 10 gauge wire from the antenna mount to the upper bolt that mounts the door to the upper door hinge.
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Next check the resistance from the antenna mount to the door frame using the lowest scale on the multimeter. It should be zero. If not, again run a 10 gauge wire, this time from the upper bolt that mounts the door to the upper door hinge. Connect the other end to the upper bolt that connects the hinge to the door frame.
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It may look like you are shorting the door to the frame by bypassing the hinge. What you are actually doing is "bonding" the large metal parts of the truck (door and cab frame) into one very large antenna ground plane for RF [radio frequency] purposes. In simplest terms, a large enough antenna ground plane allows the antenna to be all that it is capable of being. Without enough ground plane, an excessive amount of your signal is not being transmitted out the antenna. Instead, it is reflected back to the radio and that can raise havoc with the radio power transistors.
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Recheck your SWR with an external meter.
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Hopefully, that fixes the SWR problem and you will not need to bond the door frame to the truck chassis.

 

If it showing a 250 watt dead key you might have a problem with the radio. You said new to you so I am assuming you brought it used If it was a shop I would take it back. Hopefully another driver haven't sold you a shot radio

 

Something wrong with the radio. They do not do that kind of deadkey.

Also were do you have the mic gain set at???? Anything more then 12:00 is too much with a connex 4300 series.

Also with the RF gain turned all the way down it should not show more then 10-15 watts total. With it turned all the way up it may show possibly around 60 ish and swing to 300+ watts.

Also make sure you have it on AM and not on FM. the talk back is super sensitive on the connex radios. It will pickup any feedback and squeal like a pig. It is best to just leave it off. Make sur ethe 10K switch is off also.

Oh and I have had two Radio shack meters go bad. Both of them started showing higher then normal SWR when checked against another meter.

 

I know. As I said, the 4300-400 does not deadkey that high. If it is showing that high of a deadkey that something is not right. Especially with the RF power turned all the way down.
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