new antenna coily whip Ch-1= 3.0 swr ch-40=2.5 swr

[hammer0630]

I am replacing everything in my Tacoma but I am Having severe SWR problems as I noted channel 1 comes in at 3.0 swr and channel 40 at 2.5 swr This is a Browning BR-89 it has a stainless steel 16" base and about 2X4" of flat aluminum coil and the whip is stainless as well with 2 set screws. Would trimming the whip help?

 

[jazzsinger]

I am replacing everything in my Tacoma but I am Having severe SWR problems as I noted channel 1 comes in at 3.0 swr and channel 40 at 2.5 swr This is a Browning BR-89 it has a stainless steel 16" base and about 4" of flat aluminum coil and the whip is stainless as well with 2 set screws. Would trimming the whip help?

I'd be rechecking solder connections and groundplane is sufficient, before i start hacking at whip, whip should be adjustable if it has 2 set screws. cutting a whip is a last resort and your readings suggest poor ground/ bad solder connection and your positioning isn't the best, those coils are awful close to the cab metalwork.

 

[hammer0630]

I am running a thick gage wire from one of the four mount screws from the antenna mount to the frame. I believe the cab is grounded but would that help the swr?

 

[222DBFL]

That antenna needs a good ground plane under it, should be mounted on the roof IMO, and like said, check all connectors, coax and grounding of the antenna. Not a piece of wire, you need some grounding (bonding) straps. This is JMO.

 

[vkrules]

Don't trim the whip.Adjust it a little longer.Your reading shows it short. As jazzsinger said double check everything before cutting .

 

[Marconi]

I agree 0630, don't trim the stinger until you see the new antenna work with a near match first.

I think I notice the feed line running parallel up from the bottom of the antenna to the top of the side window, and it may be very close to the radiator and the cab as well.

It should be easy to check if this could be a problem. Remove the feed line and run it down to the ground. Then run it up thru the opening of the open door over to the radio. You want the feed line as far away from an RF source as possible.

This will check and see if direct radiating currents are radiating on the feed line back to the radio. It might not fully fix the problem, but if this improves the results...you can figure to have solved an issue. I use to run my feed lines under the truck up into the cab thru some convenient and safe opening I could find.

I don't like the location either and I've repeatedly heard guy's lament about their mobile antenna not working well attached to those type metal boxes too. I don't know why that is, but I know some mobile installs can be problematic.

Have you thought to test your new antenna on another mount that you know works right, just to see if you can get it to respond with a close match? Check around with some buddies who have a good mount that will accommodate your antenna. Your results so far suggest to me you have a poor groundplane connection. You could also borrow a magnet mount to check where your antenna works best.

 

[RatsoW8]

I agree with the others. Running a wire as a ground is not a good rf ground. Mount the antenna on the roof or in the center of the toolbox and bond the toolbox to the bed, bed to frame, etc. Then find someone with an antenna analyzer to do the final tuning if your going to run that amp. Otherwise all your power is going to warm the worms with ground losses and not much else.

Here's a good article that everyone mobile op should read before installing an antenna mount.

http://k0bg.com/antmount.html

 

[K4PIH]

New Antenna Coily Whip

The K0BG site is a great reference. He drives the same (or did) vehicle as mine which presents particularly difficult antenna mounting issues.

Looking at your pix I also see an amp? Don't know how you have done your testing but I would take the amp out of line and test the radio barefoot. If you are testing barefoot then I agree with the other posters that if possible, mount the antenna on top of the metal box center. Where you have it now presents an uneven ground plane which could be causing the SWR issues.

Does your radio have a built-in SWR meter? Those things are notorious for weird readings. Use a stand alone meter for best results.

73

 

[Beetle]

In the first picture, I see another antenna just a few feet from the one that's giving you the trouble. Entertainment radio? It represents another piece of vertically-polarized metal in the near field; that can play hob with any adjusting you try to make.

 

[gamegetter]

as well as all that has already been mentioned,

my thoughts are to bond the tool box to the bed with 4 bonding straps and then bond the bed to the frame with at least another 4 bonding straps. whether this will work for you remains to be seen, you will have to try it to find out.

 

[t77chevy]

If channel 1 is 3 swr and channel 40 is 2.5 swr. Then your antenna is showing short not long and cutting the whip would further complicate the problem.

First thing you need to do is relocate the antenna to atleast half way back the length of bed ..even on the end of the bed being better then on the cab of the truck.which is were your problem is coming from.

You wouldn't put a ground radial along side your base antenna would you ?...that's exactly what is happening when you mount an antenna right behind a cab or bumper mount behind a tailgate.

Also you don't want any metal around a coil atleast two times the length or width "whichever is greater" or its Q factor is drastically reduced via capacitance.

On center loaded antennas the section below the coil does the majority of your transmission. "Current maximum" and placing a ground along side it will introduce various reactance ."bad thing lol "

Move the antenna back and don't be afraid to scrape a little paint off for a good ground .Also wide short lengths of braid " less then ten inches long" should be used to ground strap your vehicle .

73

 

[dx31353]

If this antenna were to be mounted in a central position behind the cad how high above the cab should the coil be?

Sent from my SCH-I545 using Tapatalk

 

[t77chevy]

If this antenna were to be mounted in a central position behind the cad how high above the cab should the coil be?

Sent from my SCH-I545 using Tapatalk

Measure the length of coil and times by two ..say the coil is nine inches long ...you would want a minimum of 18 inch from the cab via a straight line .

 

[hotrod]

I am replacing everything in my Tacoma but I am Having severe SWR problems as I noted channel 1 comes in at 3.0 swr and channel 40 at 2.5 swr This is a Browning BR-89 it has a stainless steel 16" base and about 2X4" of flat aluminum coil and the whip is stainless as well with 2 set screws. Would trimming the whip help?

i agree with others . your location is poor at best. but being swr is close to 3.1.1 on
both ends id also include ground issues. id mount it the roof [best choice] or on the
bed rail in middle of cab but use a riser to get the mount at or just above roofline
for swr adjustment
high on ch.1 lenthen whip
high on ch. 40 shorten whip
there should be enough slide adjustment and shouldnt need to trim .however if you do
use a gringing wheel or large file be carefull not to take off much , i only trim about 1/16
of a inch at a time

 

[hammer0630]

Thanks also for clarifying swr long short 1-40 Sometimes I wish I was like others "Hey it works great!" I have replaced the nut bolt antenna mount. The coax the antenna and even the radio all for poor trancieve LOL