swr change with amp change

Doubt thats going to make a difference, but wont hurt...SWR going up when amp is turned on is a command problem, if it go's up just a point or 2 and SWR stays under 2.0, I wouldn't worry about it.

You can try doing some bonding of the vehicle, which usually takes care of SWR going up when amp is turned on...This would be running ground straps off things like the doors, hood, tail pipes, trunk lids...Adding RF grounding gives you more metal for the antenna to see, and usually will help lower SWR.

 

In general I agree with Jesse. First off always do your swr reading and adjustments with the amp out of line.

Second make sure the amp is well grounded including the case.
Wire gauge 25 foot of 10 gauge is good up to 20 amps, 12 gauge is ok for 15 to 18 amps, so you should always increase the wire gauge for a safety cushion.

Next make sure you add fuse's to both the positive at the battery and negative at the amp. These are to protect the wiring and the vehicle not the amp. The fuse always goes at the source.No greater than a 20 amp fuse.

Grounding, goes from the battery to the frame, from the frame to the engine, main body member (cab), from the cab to the doors to the mirrors. The ground point at the battery for the radio equipment to the strap to the frame should be the same location. Grounding correctly prevents ground loops which you do not want to have.

Take swr reading first with amp out of line, then inline but turned off. If you have a low swr of say 1.4 or less here this is as far as I would chase it. There are lots of dirty amps on the market without the correct equipment your not going to see if its spurious which I suspect.

Happy Hunting God Bless.

 

If it is a palomar or any other 225/250 two transistor amp of the same design - it is a pos amp.

From what I remember working on these amps, there are two problems - one is the issue with the input of the transistors not having the needed impedance for the radios through the attenuation (padding) and the other is the padding (hi/lo/med) switch isn't using the right values to actually attenuate the power down to the needed level.

I know a few of you would understand this - any grounding or other issues seems to just mask a POS amp. The best is to replace it with a good design.

 

I know I am, I have parted out maybe twenty of these POS amps in the past couple years, using the parts to build good amps for 20 and 40 meter use. All of them when tested failed one or another test. Impedance is important and it isn't hard to design it right.

It is amazing the junk that is out there, how someone can make something that screams loud and proud but throws out so much garbage RF ... and make a lot of money building junk.

 

Texas Star 667V $250.00. And I'm not that far from you. Plenty of power when you run it on low so it never gets hot and lasts forever. A big burst of power when you need it. I'd run 8 gauge wire.......or even six for it.