Floating SWR readings

[sideways]

Hey guys new newbie, Ive had three antennas hooked to three different radioson my 95 chev astro van. All combinations start out wit a great swr match the go away,sometimes to return sometimes not. Current I'm running a Ranger6300F25 w/wilson trucker 2000,black cat 300 and a roadking. Started out with 1.3:1 on the ends and 1.2:1 on 19,two days later 2.7:1 on the ends and 2.6:1 on 19 , today 1.2:1 on the ends and 1.1:1 on 19.This is driving me nuts and all set ups are with and without the amp on or in line. I don't know if it matters but there is a metal fan cover on the back of the roof. My antenna is about 3 feet in front of it and with the 10" stalk on the antenna it is above the 5' tall fan cover. Help pleeeeeeease.

[fxstsirider]

Have you taken the readings parked in the same location? I know if I am in the driveway close to the house my readings can change from different electronics being used in the house. Pull out in the street and the swr`s go back to normal. I try to out in the middle of nowhere. Where there is the least amount of interference to set mine.

[sideways]

Yes I have gone to the same place away from anything for the initial setting. It seems to take a day or two for the readings to get wacky.

[BigBopper]

I would check my Coax connectors, check any jumpers you have, even if they are new,,

[Daddyroccop]

Yea what big bopper said.....I had a similar problem turned out to be a bad jumper on the meter..wiggled it one way good swr's.... other way very high...new jumper and problem solved!

[sideways]

Thanks guys I guess its time for a little more info. The first antenna was a radio shack fiberglass whip on a galixy 959. Local tech said probably the compression adjustment of the cheap whip. Bought a k-40 roof mount ,still with the 959. same prob.(no amp at the time). Was loaned a cx3300 used the k-40,still the same prob. Bought the Ranger 6300F25 used the k-40 still the same prob. Son-in law gave me an old black cat 300 still same prob.. Bought the Wilson 2000 trucker still the same prob .. Used the heavier of the two coax radio shack sells (as a test okkkkkk) and super 8 mini coax, (the k-40 has its own coax). Also the radio swr meter gives me pretty damn near the same swrs as the seperate meter i use to set all the combinations of radios to antennas,and I've used three different jumpers, one used and two different new ones which I bought at ameture electronics (a ham radio shop around me).I've taken a reading with one jumper then switched jumpers and taken a second reading to use the radio /antenna /coax set up and the difference is minamal. The mini 8 does give me the lowest swr. I'm currently getting power from the fuse box on the horn/turn signal fuse. The only combination that the swr went over 1.5:1 was with the wilson the ranger and the radio shack r58 (the thicker coax) a flat 2.7:1 swithhed to the mini 8 took it down to about a 2.3:1 flatish drove it home let it sit for a day and its now a fairly flat 1.2:1 . Am I destined to be a mudduck all my life or is there hope/help somewhere?

[outlawmobile]

Well this may be a dumb question but are you closing all doors on the vehicle each and every time you check swrs?An open door can really throw off your meter readings believe it or not.Someone else could probably explain it better and more technically than me but I believe an open door messes with your ground plane which in turn messes with your swr readings.Shawn

[231]

Where in line is your meter and what brand is it? You cannot rely on the radio meter for this...which it appears you are doing from what I've read. The meter should be the last thing on the way to the antenna. Are these magnetic mount antennas you are using? Sounds like it to me...as a floating ground problem.

Maybe I missed something but the power source is a totally different animal. It will not affect your standing wave. However, I would highly recommend you consider running direct power to the battery for both the radio and amp. Pulling power from the fuse box (especially for the amp) isn't a good idea.

Just a couple of thoughts.

[MR. 450]

IF YOU HAVE A OHMS METER YOU CAN TEST THE METER TO SEE IF THE METER HAS A SHORT IN IT BY PLACING THE POSITIVE INSIDE THE CENTER OF THE PORT AND THE NEGATIVE TO THE SCREW PART AND SEE IF YOU GET A READING OTHER THAN 1. SAY ALL 0'S THEN THE METER IS SHORTING OUT ALSO YOU MAY GET FALSE READINGS IF YOU DO NOT HAVE AN ADEQUATE POWER SUPPLY SO MOVE THE POWER TO THE BATTERY AS STATED BEFORE THE SAME TEST CAN BE DONE TO THE JUMPERS TO SEE IF THEY ARE GOOD OR BAD

[sideways]

Shawn,ditto on tech speak but I've been all over this forum so I had all the doors closed and even took readings with the van running and with it shut off thanx

231 The floating ground was just thew easiest way for me to say what is happening. All my antennas are roof mount, And I'm busted on the meter its a radio ------ but at least its new.I've ohms tested all jumpers since last post and they are all good and the meter is the only thing between radio and antenna, I put the amp aside until I can get a good swr reading to stick around, I was only using the radios swr setting to kinda double check the ahem real meter. Between you and Mr 450 both aiming at my power I think that is my next step. My only concern about going to the battery was engine noise so I picked up a bandit noise filter which I will use after I get the swr to stay constant, thanx

Mr 450 I think between you and 231 I need to look at power in, the only thing I hadn't done any thing with in this ordeal, I would like to talk more on the meter check later, thanx


sideways wavin a hand

[231]

231 The floating ground was just thew easiest way for me to say what is happening. All my antennas are roof mount, And I'm busted on the meter its a radio ------ but at least its new.

I see...and that info' helps us understand what you might (or might not) be seeing. Been there and done that...so no worries. I would say though that if you can swing a pic for us of you mounting arrangement it sure would help. If it were me I'd be focussing on that...and making sure I run at least one additional ground strap/wire from the mount to a new and shiney metal gound point. It smells like that is the problem to me...but I'd be guessing.

On the power supply, get to it when you can. Without a reliable antenna system you are sunk anyway.

[sideways]

231, I miswrote in my last post its an ever changing swr reading (not ground ) however I'm willing to try anything at this point. Its an old work van so I drilled two different holes and sanded the inside of the roof clean where the mount(s) are Only running a single antenna just tried two spots. I'm assuming an antenna can not be over grounded then if the suggestion is an additional ground strap to the lug?And yes I have the nylon washer on top and the metal lock washer is not touching the center of the lug made positive of that, I had been wondering if the body was a good enough ground.

thanx And ouch on the Mudduck jr., was it my question ,equipment or what thats just plain meannnnnn

sideways wavin a hand

[sideways]

231, since it may be the body ground and I'm centered on the roof any suggestions. All over this forum I've heard the keep it short and its a long way roof to floor. Also looked on the Wilson web site and was wondering about their no ground kit and If you or anyone knows if it is worth a shot?

[sideways]

Thanx guys, the extra strap from the antenna base to a roof rib,roof rib to side rib ,side rib to the floor, and a 4AWG battery to the firewall have my swrs down to 1.2 on the ends and 1.1 on 19, now the test is will it stay. Now that that is done(not questioning just want to learn why) what is the benefit of the power from the battery instead of the fuse box,amps or cleaner volts ?


Sideways wavin a hand

[MR. 450]

power from the battery will allow for future additions and cleaner connections you don't know how many times the wire is split or cut down to a smaller size wire than would be needed if you were to add power like an amp also you don't take the risk of shorting out you other equipment that is ran to the fuse panel but you should have a in line fuse 1 foot from the battery and 1 foot in front of the radio i know it sounds like overkill but think of all the money tied up in your equipment and be safe not $orry if catch my drift

[sideways]

Had not thought about wire Gage and splices etc..Thanx.

[231]

231, since it may be the body ground and I'm centered on the roof any suggestions. All over this forum I've heard the keep it short and its a long way roof to floor. Also looked on the Wilson web site and was wondering about their no ground kit and If you or anyone knows if it is worth a shot?

Thanx guys, the extra strap from the antenna base to a roof rib,roof rib to side rib ,side rib to the floor, and a 4AWG battery to the firewall have my swrs down to 1.2 on the ends and 1.1 on 19, now the test is will it stay. Now that that is done(not questioning just want to learn why) what is the benefit of the power from the battery instead of the fuse box,amps or cleaner volts ?

Woh, sideways I'm sorry I missed your posts!!!
Dang...I hate that when that happens.

Keep what short, the coax? Use whatever amount you need to effectively reach the antenna. Period. Same with additional ground straps. And indeed you are correct, no such thing as too much grounding. Your description of the "floating grounds" was very good by the way. STBR on the forum here ran additional ground straps darn near everywhere on his truck. Made a difference on his performance...and I've done the same thing too over the years with the same results as he had. My old Jeep Cherokee was a coastal rig with lots of corrosion and rust. It required a ton of new ground connections...but once that was done, I never had SWR issues (assuming everything else was okay).

And as far as the power goes, the battery acts as an insulator. It helps protect some from unwanted electrical noise(s) from other systems in the rig. It's the cleanest power source vehicles have to offer.

Looks like you are on the right road for a fix though. Nice job!