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KL-203 question

jr26

New Member
May 5, 2022
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I am looking to hook up KL-203 in 2 of my cars, I may mount them under the dash but the switches would be hard to access. Does the amp need to be turned off when not in use?
 

kc8mob

Active Member
Sep 26, 2017
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If you drive the cars regularly, then no. They don't draw any idle current worth mentioning.

You can effectively power the little 203's from a quality banana jack style Cig/Accessory jack as well. It'd be silly to run dedicated power to the battery through the fire wall for an amp of that class.
 
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ForestRunner98

917 SoCal
Feb 9, 2020
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If you drive the cars regularly, then no. They don't draw any idle current worth mentioning.

You can effectively power the little 203's from a quality banana jack style Cig/Accessory jack as well. It'd be silly to run dedicated power to the battery through the fire wall for an amp of that class.
I guess I am silly. LOL

I run a line to my 203. I don’t trust the cig lighter. I think it’s a 8ga power and ground. Good thing it’s good for a bigger amp.

But ya OP you can leave it on.
 

kc8mob

Active Member
Sep 26, 2017
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I guess I am silly. LOL

I run a line to my 203. I don’t trust the cig lighter. I think it’s a 8ga power and ground. Good thing it’s good for a bigger amp.

But ya OP you can leave it on.
Well we'll just call that planning for the next purchase you hide from the War Department!

But if someone never intends to go bigger then a 203, a quality cig lighter setup is plenty. Most new-ish cars are 15 amps.

I run dual/parallel 4 awg hot & ground in my Tundra. But most of the time I'm just running my IC-706MKIIG so in other words.. 100 watts hehe but legal limit is but a switch flip away :)

1500+ real watts on tailgate mounted HF quarter waves puts the guy in the drivers seat in a high radiation environment though.
 
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jr26

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May 5, 2022
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I think I am going to mount it where I can flip the switch from the under the dash probably use 12 gauge wire amp draws 10amps my next question is what antenna cable should I use with this one setup is in a jeep and only a few inches will be exposed the other in a truck and most of the cable will be under the cab
 
Oct 27, 2020
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I run a 203 and my radio in the car with the cigarette lighter and the 203 is always on. I have an ex police fleet vehicle and that may help with running everything through the cigarette plug.
 

kc8mob

Active Member
Sep 26, 2017
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I think I am going to mount it where I can flip the switch from the under the dash probably use 12 gauge wire amp draws 10amps my next question is what antenna cable should I use with this one setup is in a jeep and only a few inches will be exposed the other in a truck and most of the cable will be under the cab
Well 12awg wire is plenty for that amp. It certainly won't hurt. If you're not up to speed on making your own coax cables. Just use any standard length you can get pre-made between the radio and the Linear! And the same for the antenna. Use whatever is the closest in length to what you need.

Assuming you're not running a quarter wave whip and instead a shortened and 'Loaded' antenna.

A loaded antenna in this case will be much friendlier with any length of coax feeding it as far as matching it for lowest swr. 1.5:1 match is nothing as far as antenna efficiency is concerned. But you want to stay at or below that with those little MOSFETs making up the output section in that amp. If your duty cycle is nice and low (Swing) then I wouldn't even be too worried about 2:1

But if your radio is stomping on the little guy then give extra attention to your antenna match.

Loosely coiled excess coax in the vehicle is ok as well. You just don't want an extra 10-30 feet in the trunk
 
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jr26

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May 5, 2022
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Feeding the amps with president Bills I am going to turn them down the truck will have 102" stainless whip the Jeep will have a double barrel skip shooter. Not sure idf I should get rg8x, rg58? Also red some of the Chinese cables on amazon are not very good any recommendations on brands. Truck has a Belden mini 8 cable from 2006 still in it so I may reuse it.
 

kc8mob

Active Member
Sep 26, 2017
79
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Feeding the amps with president Bills I am going to turn them down the truck will have 102" stainless whip the Jeep will have a double barrel skip shooter. Not sure idf I should get rg8x, rg58? Also red some of the Chinese cables on amazon are not very good any recommendations on brands. Truck has a Belden mini 8 cable from 2006 still in it so I may reuse it.
Well not withstanding general aging due to weather and the elements. Beldin is legit. I use Beldin rg8x mobile. Scored a big roll a ways way back.

We just did some tests on Jetstream rg8x and Christ a Light. It's total crap. Even for HF.

So go to DX Engineering and get some of their rg58 or rg8x 'Jumpers" At your power class rg58 is just fine, but in the real world either one pinch or smoosh the same going out a car door for example.

The 102" whip is the best mobile you can run. If you put the time in to match it to the install.

Even in the center of your roof they aren't a 50 ohm impedance.

So it's completely possible you'll need to trim it shorter. However it's more common that it needs to be longer and a big ass 6 inch spring will help you there.

I run a 102" whip mobile for 10m. I had to use a spring (You should anyways) and then trim about 2.5 inches off. On top of that. I had to calculate an "Electrical" wavelength compensated for the velocity factor of the coax. Once I had that completed I have a damn near flat match from 29.000 down to high CB band.

Every antenna install in unique. I also have my Tundra RF grounded though. Every panel is tied into something else twice with 1 inch RF braid. As well as the mounts on both sides of the tailgate being tied in down under the bumper with RF braiding.

My ridiculous setup isn't the point. Just be prepared to tune the 102" whip. You'll most likely start out at a 2:1 match possibly more.

I'd keep the carrier drive power to your 203's at a watt. Or maybe less.
 

jr26

New Member
May 5, 2022
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I was considering this procomm wire RG8X or should I look for belden? the 102" whip is mounted on a truck tool box on the driver side no spring seemed to work very well with the Connex 4400hp. The local shop set the swr for me, I rember him saying it was very good he did not trim anything. I recently bought a MFJ-872 to set it myself.
 

kc8mob

Active Member
Sep 26, 2017
79
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I was considering this procomm wire RG8X or should I look for belden? the 102" whip is mounted on a truck tool box on the driver side no spring seemed to work very well with the Connex 4400hp. The local shop set the swr for me, I rember him saying it was very good he did not trim anything. I recently bought a MFJ-872 to set it myself.
You'd be fine with that cable really. Short runs and low power so no need to split hairs really.

Do check your swr at high power output. Carrier.

It's possible the guy was playing straight about the swr but, there's no adjustment on a whip besides adding spring length and or trimming.

They are 102" long because the assume a 6 inch spring will be used which gets you closer to resonance on the CB band.

I'd order a spring and use it.

Also I need to clarify my comment about my coax length. I ended up at a velocity factor adjusted 3/4 electrical wavelength run. Not a full wavelength.

Unloaded quarter waves are the best mobile antenna you can operate. But you have to work to get the system into resonance.

Once you do, you get the advantages of bandwidth.

Coils (inductors) full the system into thinking the system is the right length.

Antenna surface area is where it's at.

Longer and thicker the better.. Enter jokes here!
 
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