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AFChap · 08-28-2006, 05:46 PM

I am trying to tune the OEM CB antenna on my coach. I borrowed an SWR meter, and have found that moving the shaft up or down (via loosening the set screw) does not allow me to get the SWR meter out of the red portion of the meter, (which I read to be 3.0 and higher. I have taken readings only on channel 19 Spouse is my inside assistant with me on the roof ...difficult process at best even with radio headsets as she is not at all technology inclined. According to her, my adjustments in moving the shaft up or down had little if any effect on the meter. What is my next step?

AFChap · 08-28-2006, 05:46 PM

I am trying to tune the OEM CB antenna on my coach. I borrowed an SWR meter, and have found that moving the shaft up or down (via loosening the set screw) does not allow me to get the SWR meter out of the red portion of the meter, (which I read to be 3.0 and higher. I have taken readings only on channel 19 Spouse is my inside assistant with me on the roof ...difficult process at best even with radio headsets as she is not at all technology inclined. According to her, my adjustments in moving the shaft up or down had little if any effect on the meter. What is my next step?

troth · 08-29-2006, 03:35 AM

Paul, doesn't your antenna have two little chrome rings that can be rotated so they go up or down on the black plastic core? The two chrome rings are what you adjust for lowering your SWR. They should be set in about the middle, then key the mike. You, on the roof, should be lying down or stay about 6 feet away from the antenna (yes your proximity to the antenna can affect SWR, just like overhead tree limbs and close buildings). Adjust the rings up higher on the threads about 1/16", then re-key the mike and compare to first SWR reading. Then readjust the rings, re-key the mike, compare again. Keep in mind you could be adjusting the rings the wrong way. That's why you need to compare readings after adjustments. And move the rings in small, about 1/16" to 1/18", height adjustments. You're trying to get the lowest reading. If you get around 1.5 to 1.75 with Winnie's stock antenna, I'd say that's pretty good.

If you don't have the chrome rings, and you've adjusted your stainless whip height as high as it can be and the SWR still isn't coming down, I'd say get a good pair of Klein wire cutters and trim 1/8" off the whip, then bottom it out in the mount, tighten the set screw. Then start checking SWR all over again, each time moving the antenna up in 1/16" increments.

AFChap · 08-29-2006, 06:13 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">doesn't your antenna have two little chrome rings that can be rotated so they go up or down on the black plastic core? </div></BLOCKQUOTE>
Bingo!! I wondered what function those two threaded rings played!! They are currently all the way to the bottom of the plastic core. Thanks for the education

When the sun comes up tomorrow and dries off the slippery roof, I'll be back up there to move them up a bit and get another reading!

I've never had an antenna like this one ...had two K-40's over the years and a cheap bottom load I got in the 70's and sold in our garage sale a year ago last April. I figured there had to be a simple answer as the reception on the antenna right now is very good ...but SWR ranges from 6.0 to 8.0 over the 40 channels!!!

Joe-K · 08-30-2006, 02:59 AM

Troth hit the nail on the head .... the chrome rings are the tuning adjustments.

I was just looking at the CB wiring diagram on the Winnebago site a couple days ago, and I recall that there is a note on the drawing that the installer is to put the rings at the highest point and lock them there at the factory. It might be that at the highest point, the SWR is usually acceptable as a starting point.

The reading you're getting does seem awfully high though. Usually a reading of 3 or above indicates a serious problem such as a short or missing ground. I hope tuning brings it down to an acceptable level and that there is not another problem also.

Let us know you fair

AFChap · 08-30-2006, 04:11 PM

I got the rings as high as they will go, and got better readings. With rings full up and antenna down as much as it will go in the mount, Ch 1 is 1.75, Ch 19 is 2.25, Ch 40 is 3.0. It occurs to me that the mount they created with the pivot then the spring on top of that may make the antenna too long. I could clip a bit off of the mast, but probably will just leave it for now as I normally monitor 19 pretty much all the time except for when I go to the weather radio.

John Harrelson · 08-30-2006, 07:12 PM

Hey Guys,

Whats the name of that antenna ?

I have been deeply involved with CB radio since the late 1960's and have never seen an antenna that had rings to adjust the SWR..

By golly that sounds like a neat and simple way to tune an antenna instead of cutting off the mast shaft a quarter inch at the time..

Who sells that brand and what is the price ?

Thanks,
John

AFChap · 08-31-2006, 04:07 PM

John

All I know is that Winnebago apparently uses them on all their factory installs ...I looked around the campground we are in and saw the same thing on all the Winnies there. You probably could find out the brand name/model by calling Winnebago Owner Relations at 800-537-1885.

John Harrelson · 08-31-2006, 06:22 PM

Thanks Paul, I'll check it out
John

NeilV · 08-31-2006, 06:40 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by John Harrelson:
Hey Guys,

Whats the name of that antenna ?

I have been deeply involved with CB radio since the late 1960's and have never seen an antenna that had rings to adjust the SWR..

By golly that sounds like a neat and simple way to tune an antenna instead of cutting off the mast shaft a quarter inch at the time..

Who sells that brand and what is the price ?

Thanks,
John </div></BLOCKQUOTE>

John,

According to the Winnebago parts manual it is an ADVANCE 8604 CB Antenna. I'll check the black bag when I get my coach back from service to see if there is any further info in there.

I am currently without CB and am looking for a replacement for my old Cobra21 which I lost when my Vectra burned this past Memorial Day. Been out of the loop so long that I am not up to speed on who are the top contenders nowadays.

Regards,

John Harrelson · 08-31-2006, 07:26 PM

Thanks Neil, I'll keep an eye out for your post.
John

future5ers · 09-01-2006, 07:27 PM

Forget tuning your stock antennae. Stop in to your nearest truck stop and get one or two Francis antenna, what ever your rig has on it. These antenna are eletronically tuned at the factory. Tried tuning stock anteenna on my big truck, the tech told me to go in and get two,perfect match, no tuning needed.

NeilV · 09-03-2006, 08:47 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by future5ers:
Forget tuning your stock antennae. Stop in to your nearest truck stop and get one or two Francis antenna, what ever your rig has on it. These antenna are eletronically tuned at the factory. Tried tuning stock anteenna on my big truck, the tech told me to go in and get two,perfect match, no tuning needed. </div></BLOCKQUOTE>

No good for a motorhome. The Wilson Francis antennas are ground plane units and not for use on vehicles with non-metalic roofs.

Jerry Wessel KA8MBK · 04-18-2007, 11:09 PM

I have found over the years that checking all connections makes a big difference. I use a MFJ antenna analyzer and you would be surprised how far out of band most antennas are.
a cb band is 27 mhz and mine was 31.
also if you have the all in the mike CB throw it away. they are the worst there is. I use a Cobra 29 and they are great. My stock antenna on my Mh works great. Just takes time to set it up and keep connections cleana and tight.