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Bearcat 980 w/ AD-203
- Thread starter Spidermonkey
- Start date
OK......not a good idea to mount it on a flat fiberglass truck box cap? (Tonneau cover) I plan to ground the ball mount to the frame. Is that not a good idea? Only other option would be to weld an extension to my hitch out towards the end of the bumper and mount it to that. I don't want to mount it to my bumper.
The issue with trying to ground an isolated long whip would be the ground wire becoming part of the antenna rather than establishing a ground plane it would most likely try to form a dipole "untuned at best". That could cause ground looping, interference issues with windshield wipers etc. Now It may not, but at this point mounting as low to the ground at the rear of the truck is most likely the best idea.
The pros and cons of mounting a 1/4wl whip on a bumper are:
1) have to drill the bumper
2) don't have to be concerned about overall height/clearance
3) have to know that your transmit radiation pattern will be skewed but will work.
The pros and cons of mounting a 1/4wl whip on the roof are:
1) having to drill a hole in the roof (pulling and replacing roof liner and routing coax)
2) have to be concerned about overall height above ground (low branches, pulling into the garage, etc)
3) greater height above ground with a more uniform transmit radiation pattern
1) have to drill the bumper
2) don't have to be concerned about overall height/clearance
3) have to know that your transmit radiation pattern will be skewed but will work.
The pros and cons of mounting a 1/4wl whip on the roof are:
1) having to drill a hole in the roof (pulling and replacing roof liner and routing coax)
2) have to be concerned about overall height above ground (low branches, pulling into the garage, etc)
3) greater height above ground with a more uniform transmit radiation pattern
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Shadetree Mechanic
Delaware Base Station 808
You could make a ground plane under the fiberglass with a sheet of aluminum. Glue it to the fiberglass with liquid nails and then ground it to the frame of the truck and bed.
Forgive my my lack of knowledge. So when you run a ground wire its not the same as it being mounted to the ground? Good to know. I swear I have seen guys run whips on fiberglass caps that's sort of why I figured it would work. Boy..this RF stuff is strange. And here I was asking about amplifiers and I can't even hook up an antenna. Lol. Can we say walk...no crawl before run? Haha. I'm handy with a soldering iron and a multimeter on old audio equipment...this is much different.
Even mounting it to the bed rail behind the cab may not work..mine didn't on a 2017 ram. Swr wouldn't drop below 3 and I found the bed is mounted on rubber! I have since went with a Tram triple magnet mount on the roof with a Tram TBC-9 antenna, I have a 980 SSB into a KL203p and besides the swr issue you need to fix you also need to drop the radio deadkey to 1 1/2 - 2 watts or the amp won't last long. You will need a external SWR meter as the internal will be off after dropping the deadkey and the radio test mode will show a fail on TX due to low deadkey. But this is a great radio setup. The one piece of advice I will say is buy the biggest amp you can or your going to want the bigger one soon.
Shadetree Mechanic
Delaware Base Station 808
RF does some strange things and is not always easily explained. From what I understand, RF ground is like the zero reference for the RF signal. The RF power uses this reference to work against. In the plastic tool box situation, sure it will work but the coax shield becomes the ground and because it is so small it will radiate power too. Some people improve their vehicle ground plane by bonding the hood, doors and fenders to the main body shell. Then bond the main body and even the exhaust to the frame. If anyone knows of any good links that might explain this a little better please post them. I am not coming up with anything at the moment.
OK...so decided to make a mount by taking a piece of 1" square tubing and welding it to my hitch frame. You may have seen the towing "skirt kits" that people have when pulling trailers. Same idea. The tubing runs parallel to the bumper close up underneath and extends just enough past the bumper to have room for the antenna mount. I got everything clamped in place to test before I welded it up. SWR was at 1.0 on the radio and and about a needle width past 1.0 on the analogue swr meter. Welded it in place, ran the cable properly and of course the cable was about 18" too short to reach where I needed to in the cab. I have some PL259 ends and RG-8u I can use but just need the female-female adapter so orderer them. I did retest the radio after running the line and same readings. I'm a happy camper now. I never did order the barrel spring..so this is the 102whip straight to the stud through the mount. Same readings on 1 and 40 or at least I couldn't see a difference.
OK...now back to Amplifiers...
I noticed RM Italy makes a 503 model and you can set the amplification. Any reviews on this one? Looks to be about double the amperage of the 203 and double the cost....but also understand that you don't get double the "range" as the power/distance curve is exponential from what I read.
OK...now back to Amplifiers...
I noticed RM Italy makes a 503 model and you can set the amplification. Any reviews on this one? Looks to be about double the amperage of the 203 and double the cost....but also understand that you don't get double the "range" as the power/distance curve is exponential from what I read.
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Did you look at the 503 at all? What was your main reasons for the 203 vs the 503? price? size?
Well....503 is on order. Cant wait. Like a boy waiting for the ice cream truck.
Any recomendations for Dead Key on this amp? I have been reading everything from guys running stock output to down to 1watt on the 503. I was going to set at around 2 to 2-1/2 watts. Most likely will have it set at position 4 and leave it as it seems after that the gain in actual effective output is limited (based on my youtube demo observations). Specs say input amperage between 12-30A. Thats a big range....Trying to determine what gauge wire im going to run from the battery. Leaning towards 10 as it will handle the 30A. Still debating on where to mount this. I assume that I dont want the In and Out coax running parallel up next to each other as might get some interference?
Any recomendations for Dead Key on this amp? I have been reading everything from guys running stock output to down to 1watt on the 503. I was going to set at around 2 to 2-1/2 watts. Most likely will have it set at position 4 and leave it as it seems after that the gain in actual effective output is limited (based on my youtube demo observations). Specs say input amperage between 12-30A. Thats a big range....Trying to determine what gauge wire im going to run from the battery. Leaning towards 10 as it will handle the 30A. Still debating on where to mount this. I assume that I dont want the In and Out coax running parallel up next to each other as might get some interference?
Shadetree Mechanic
Delaware Base Station 808
Sounds like a good plan to me. The only thing I know about that amp is what I have seen on you tube. A variable dead key on the radio would be ideal so the amp dead key could be easily set. Or set it at 2 and see what you get. Generally you would want to set the amp dead key at 1/4 of its output at 100% modulation. I think that's why position 4 on the power knob is recommended. It lets the amp have enough headroom so it doesn't flat top the peaks. As far as the parallel coax, I don't think it would be a problem as long as its not coiled up together.
I would run 8 awg positive and negative straight to the battery with a fuse on the positive at the battery. Ten awg would probably be ok but the amperage rating of a wire is always with a certain amount of voltage drop. How much voltage drop is acceptable is up to you. Some people ground the amp to the body of the vehicle but then the factory wire that goes from the body to the battery has to be big enough too, this is why I just go straight to the battery with the negative. Set us know how the install goes and maybe even snap a few pictures for us.
I would run 8 awg positive and negative straight to the battery with a fuse on the positive at the battery. Ten awg would probably be ok but the amperage rating of a wire is always with a certain amount of voltage drop. How much voltage drop is acceptable is up to you. Some people ground the amp to the body of the vehicle but then the factory wire that goes from the body to the battery has to be big enough too, this is why I just go straight to the battery with the negative. Set us know how the install goes and maybe even snap a few pictures for us.
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