Checking SWR...SWP'd General Lee

[Red Drum]

I'm awaiting my SWP'd General Lee & RA250 from Radiocative. When I install the radio and check the SWR, is it correct that I check it with the power setting on low? Alos, is 8 ga. the correct wire size to run for the positive and negative?

[BigBopper]

yep,,yep,,,you got it,,,you'll love that radio!! Run the power wire to the battery, and your ground to the seat post,,,or anywhere close to that,,not to the battery,,,you will bring some noise in if you ground to the battery

[BigBubbaBD]

yep,,yep,,,you got it,,,you'll love that radio!!

Correct me if im wrong please.

But shoulnt you set it at low but then still check it at full to make sure your setup can handle the watts?
the Antenna/location and height in relation to coax would still be the same so your SWR's "should" still be the same if your system can handle the watts.
But
as I cound out it can be PERFECT on low watts but as soon as you put some power to the antenna you find that it cant handle it and SWRS go threw the roof.

[atfgy]

I thought you never wanted to check SWRs with any kind of power.. so setting it to low would be ideal

[BigBopper]

This is a quote from RadioActiveMan

I wrote this in another section but will retype it alittle. My my example was if your tuning a antenna like a pred 10K out of the box the SWR are is going to be HORRIBLE! If you can avoid having a 200 watt radio as the load that would be a great thing.
SWR is a ratio of how many watts are coming back. Kinda like when you flush a toilet you want 100% of the stuff going down. However on a bad toilet some comes back up. This is like a mismatched antenna. If you can make the radio watts low tuning a very poorly matched antenna your better off. High SWR can damage radios, so if your mismatched and doing 200 watts, its alot faster to blow up your radio then a 4 watt cobra.
You guys just fine tuning a antenna, or something like it YOUR FINE! Just tune your antenna as needed!

Hope Mike you don't care I quoted you,,,BB

Ive said it a zillion times, a antenna can be 100% tuned for a low watt radio. However sometimes SWRs go up, when your load is alot bigger. Under full load the antenna/mount/coax is having a issue.
I had a customer in AZ, perfect antenna 1.1 However with a 2x8 davemade swrs went crazy. His shields on his coax were not PROPERLY soldered!
In a perfect world SWR wont change no matter what radio you use. The key is however when they do, your system has a issue, someplace.

[Mr RadioActive]

Never mind your help Bopper you A#1!!!

On a Lee its a little different. Your not tuning a antenna with a 200 radio, your tuning it with a dual final radio. Your low power being matched for an amp is going to be alittle above 1 watt for a RA 250. SOOOOOOOooooooo that being said you'll need to tune on high since low prob wont even calibrate the meter...

[Red Drum]

OK guys...the SWP'd General Lee, RA250, & Wilson Mag1000 are up and running. I'll send some pics of the installation in when I get a chance. No problems and all of the feedback I am getting is positive..."Loud & Clear". I do have a concern about the SWR's and was hoping someone would crunch the numbers and tell me what they thought. Per the antenna instructions anything between 1.0 & 1.5 is "excellent" & anything between 1.5 & 2.0 is "very good". Here they are...

Between Radio & Amp (W/Mic Gain & RF Gain off, amp off, radio switched to high per Mr. RA)...

CH 1 - 1.1
CH 20 - 1.3
CH 40 - 1.7

Between Amp & Antenna (W/Mic Gain & RF Gain off, amp off, & radio switched to high per Mr. RA)...

CH 1 - 2.0
CH 20 - 1.3
CH 40 - 1.1

As you can see, the readings are flip-flopping/reversing when comparing the two sets of meter readings. Is this normal? I tried changing the 6' coax between the radio and amp to a 3' section but that made CH 1 go even higher to 2.5 so I went back to the 6' section. Also, when I lower the antenna 1/4", CH 40 lowers but Ch 1 rises. I really don't want that since I do talk on the channels below 20 mostly.

Any feedback would be appreciated. Thanks, Red Drum

[Phaze91460]

Ugg, sounds like some of the unusual SWR problems I have had. Never did figure out just what my problem was.

[Red Drum]

That's my luck. When I first installed the antenna, I was using the meter on a fairly new Cobra 29 for what it's worth. It was showing 1.1 across the channels. I'm presently checking with a new Radio Shack meter and I do have the addition of an amp. I'm really not too worried about my transmissions. I'm getting out great & receiving great. Just want to make sure these readings are not hurting the equipment.

[Rex_foxhound]

I assume you Calibrated the meter before switching it to SWR.

The meter is supossed to be the last thing in line before the antenna... radio-amp-meter-antenna.

So, looking at your readings between amp and antenna, ch 1 is higher than 40 which means your whip is too short. Stick it all the way in and pull out about 1/4 inch each time and check it. Try to get it below 1.3 on 1- 40.

Have you checked your swr with the Rad Shack meter with just the radio and antenna? I would try that 1st and see what the readings are. My readings don't move when I use just the radio and antenna and then when I put the amp in line and turn everything wide open. They stay below 1.2 on all channels.

Hopefully you won't have too much trouble figuring it out.

[BigBopper]

sounds like you might have a ground or a coax jumper problem

[Mr RadioActive]

Did you ever cut the whip? Is that with the amp off or on?
the real way to test it is take the amp out of line, put your meters in its place, whats it reading then?

[Red Drum]

Thanks for the help Mr. Radioactive, BigBopper, & Rex_foxhound!

Removed amp and replaced with meter. Did a little adjusting to the antenna @ the base and here's what the readings are now...

General Lee switched to "Lo" (RF Gain Down, Mic Gain Down)

Ch 1 - 2.5
Ch 20 - 1.0 (no needle movement)
Ch 40 - 2.5

General Lee switched to "Hi" (RF Gain Down, Mic Gain Down)

Ch 1 - 3.0
Ch 20 - 1.1/1.2
Ch 40 - 3.0

Should I tweak anymore? Keep in mind I have a Wilson Mag1000... 39"/short load whip that has adjusting screws @ the top & bottom of the load.

Thanks again!
p.s. I'm planning on making donation to the forum for all the help I've received. Don't have any cb shops near me and everyone here has been a great help.

[Rex_foxhound]

Hmmm... All I can say is maybe get a different jumper, other than the 2 you have now, and check it again. Maybe somebody else will know more.

[Gadfly]

Here's a little suggestion if you are nervous about trimming the whip. I sometimes straigten out a coathanger and trim it to length. When I get the SWR right with the hanger, I substitute the whip and trim it. Then I am not as likely to make a boo boo and have to seek out a new whip!

73

Gadfly

[Mr RadioActive]

Dumb question but where are you locating your magnet mount? 2.5 chn1 2.5 chn 40, 1.1 on 20, is NOT normal for a wilson mag, its getting weird reflect for some reason. Is that on a roof?

[stickman]

IS YOUR COAX FROM THE ANTENNA RUNNING RIGHT NEXT TO YOUR POSITIVE OR NEGATIVE WIRES BY CHANCE? THIS MAY SOMETIMES CAUSE THE SWR'S TO BE HIGH! IF THEY RUNNING NEXT TO EACH OTHER TRY RUNNING EITHER THE COAX OR YOUR POST. & NEG. WIRES A DIFFERENT ROUTE! JUST A SUGGESTION! GOOD LUCK WITH THE SWR PROBLEM HOPEFULLY YOU WILL GET THEM DOWN TO WHERE YOU DON'T HAVE TO WORRY!
STICKMAN

[Red Drum]

I gave you some bad numbers with the radio switched to "Hi'"...here is what it should be...

Ch 1 - 3.0
Ch 20 - 1.0 (just barely moving the needle)
Ch 40 - 3.0

The antenna is on the cab roof about 3/4 way toward the rear (centered). What is obtainable and what should I be shooting for with the Mag1000.

[Rex_foxhound]

Well, you should be looking for 1.3 or less across all 40 channels.

Try moving the magnet to a different location on the roof and see what happens.

[Red Drum]

Dang It! Gave you wrong numbers again! I think I'm losing it and you probably think I am too. I've been giving you wrong values all along. I was tired and rushed yesterday evening and when adjusting I was referencing how many marks on the meter above 1.0 that I was seeing when going back & forth comparing ch 1 to 40. Later in the evening, I was even more tired, and typed it that way. Thanks for bearing with me. Did a little more adjusting of the antenna today in a field beside my house w/nothing around. I just locked her down and here are the readings.


Ch 1 - 1.2
Ch 20 - 1.0 (no needle movement)
Ch 40 - 1.2

Does that sound more like it?

[Rex_foxhound]

Thats more like it!