Community Forums

park_ridge_dave · 09-28-2006, 02:25 AM

Hi I have slapped a CB in our 2003 Scottsdale (a $3.00 Yard sale special) to monitor CH 19 and as a backup to the cellphone. I checked the SWR on 19 and it was a little over 2.0 to 1. It works OK, but not fantastic

.

Well I have bought a really good CB to install (Galaxy 959) and I can't find any antenna info in the Newmar Data sheets supplied with the rig. Anybody know the model number/supplier of the antenna?

I would like to tune the antenna now that I am getting serious

. But I don't have the procedure(s).

Thanks,

park_ridge_dave · 09-28-2006, 02:25 AM

Hi I have slapped a CB in our 2003 Scottsdale (a $3.00 Yard sale special) to monitor CH 19 and as a backup to the cellphone. I checked the SWR on 19 and it was a little over 2.0 to 1. It works OK, but not fantastic

.

Well I have bought a really good CB to install (Galaxy 959) and I can't find any antenna info in the Newmar Data sheets supplied with the rig. Anybody know the model number/supplier of the antenna?

I would like to tune the antenna now that I am getting serious

. But I don't have the procedure(s).

Thanks,

Dave Killey · 09-29-2006, 06:09 AM

My 2004 scottsdale did not come with any CB antenna as far as I know. I had to install one myself.

Mahlon · 09-29-2006, 09:00 AM

That antenna is a part of the "CB Radio Prep" option & is a standard Newmar part; the local Newmar dealers have lots of them in stock. Whether or not they have any technical data for them is another matter.

In my professional opinion, 2:1 is a pretty good match given the extremely short physical length of the antenna & commensurately high inductive loading needed to get it to resonance. It likely doesn't have much of a ground plane either.

That said, I have exactly the same factory antenna configuration as you do & you've piqued my curiosity. I'll sweep mine with an analyzer this weekend & let you know the results. And, of course, I'll see if there's a way to adjust the whip length.

park_ridge_dave · 09-29-2006, 12:46 PM

I took a look at my antenna last night. I am wondering if it is what the Winnebago group calls the "rusting winnie antenna". It appears to have the adjustment/locking ring set up. I have been searching all over to get a Mfr/Part number but so far no luck. Also, you are probably right, maybe I should just leave well enough alone

at 2.0:1 SWR.

Anyone able to hazard a guess?

Mahlon · 09-30-2006, 06:32 AM

Well, it looks like I'll have to eat some of my words. Mine hit resonance at 26.640 MHz at 1.1:1 VSWR, meaning of course that the whip is too long. But at least it can be cut to present a reasonable match.

It appears that the whip is held in with the usual hex set screw. Loosen set screw, remove whip, cut off 1/4 inch, replace, re-test, repeat until happy.

Mine also has two knurled aluminum lock rings on the black platic loading coil. I have no idea what those are for, but if you wish you can play with those to find out.

Good luck, let us know how it turns out.

park_ridge_dave · 09-30-2006, 01:13 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Mahlon:
Mine also has two knurled aluminum lock rings on the black platic loading coil. I have no idea what those are for, but if you wish you can play with those to find out.

Good luck, let us know how it turns out. </div></BLOCKQUOTE>

Thanks Mahlon:

The knurled rings are the thing that I am curious about. The Winnie Guys say that they have some instructions to tune the VSWR using one of the rings and that the other ring is a "jam" nut to hold the adjustment.

I was trying to determine which is which (rings) and if, indeed, ours is the same antenna that they are using.

Thanks for your input, I am going to get out my SWR meter and have at it tomorrow. I also have a good dummy load and a power meter so I'll let you know if I find out anything more. I'll try to take some pics too.

BTW I'm K9FZJ (since 1958) so I like to fiddle around with this stuff. I may put my elecraft HF rig in the MH to play around with too.

Cheers,

Mahlon · 10-01-2006, 03:51 AM

Oddly enogh, there is a thread over at RV SYSTEMS AND TECHNOLOGIES / Technology, Internet, Cell Phones, Creative Solutions, etc. / CB Antenna tuning where they're talking about the same thing.

park_ridge_dave · 10-01-2006, 06:00 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Mahlon:
Oddly enogh, there is a thread over at RV SYSTEMS AND TECHNOLOGIES / Technology, Internet, Cell Phones, Creative Solutions, etc. / CB Antenna tuning where they're talking about the same thing. </div></BLOCKQUOTE>

Just waiting for the camera to charge up (for the pics) and then I'm off to do battle with the antenna gods

While I'm waiting I'll go look at that thread.

Thanks as always

park_ridge_dave · 10-01-2006, 03:14 PM

Well I made it over to the rig today. My antenna has the two rings and I took a good SWR meter plus I found a little help for tuning my antenna in a post on one of the threads I found.

"Saw this when I was searching for something else in my manuals....

Antenna SWR Adjustment-

To adjust- Check SWR on CH1 and CH40.
IF CH1 is HIGHER than CH40,turn tuning ring CLOCKWISE.
IF CH40 is higher than CH1,turn ring COUNTER-CLOCKWISE.
USUALLY 1/4 to 1/2 turn is enough
REPEAT until CH1 and CH40 are the same.
DO NOT TRIM WHIP!!"

I figured what did I have to lose?

My first readings:

Chan 1 1.2:1
Chan 20 2.0:1
Chan 40 3.0:1

I turned the ring 1/2 turn CCW

The readings

Chan 1 1.5:1
Chan 20 1.0:1
Chan 40 1.5:1

I was floored! I just couldn't believe it worked that well!

I "locked" the bottom ring with the top ring and rechecked the SWR. It stayed the same.

The search that actually found all the "good stuff" was "CB ANTENNA TUNING" (all forums)

There are several threads going on this. So be prepared for a lot of reading.... or just follow the procedure above.

Remember, you need an SWR meter to set up the antenna. Or take the procedure with you to the CB shop for the tech to reference if you have it done.

Thanks to Mahlon and everybody for the help.

Cheers and Gud DX

Mahlon · 10-02-2006, 04:31 AM

Hey, that's terrific! I guess that those rings act like a shorted turn over the loading coil in the base.

Ya know, that also means that that antenna could probably work pretty well on 10m too (albeit with a bit of whip trimming). Or at least somewhat better than a dummy load.

(KIDS! Don't try any of this at home unless you have Proper Antenna Measurement Equipment)

park_ridge_dave · 10-02-2006, 12:13 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Mahlon:
Hey, that's terrific! I guess that those rings act like a shorted turn over the loading coil in the base.

Ya know, that also means that that antenna could probably work pretty well on 10m too (albeit with a bit of whip trimming). Or at least somewhat better than a dummy load.

(KIDS! Don't try any of this at home unless you have Proper Antenna Measurement Equipment) </div></BLOCKQUOTE>

Hoooo boy are you a deviate.... errrr I mean Devious

That is an exceptionally good Idea, as the "screw in" portion is readily available (I am told) so you could experiment easily. Yes, I could see where it would be easy to band change just by swapping the screw-in portion.

Just had a thought, a lot of guys were complaining about the "rust" on their antennas. I plan on unscrewing mine (and the duck for FM, not for rust prevention but because of the cover when I cover the rig for storage this winter

. I wonder if the guys know how easy that is to do? I am also buying a little conductive grease to smear on the remaining screw holes to prevent rust on them as well. The antennas will be warm and dry down in the ham shack glistening in a light WD-40 sheen on the metal parts.

And say Mahlon, did anyone ever tell you that your picture bears a strange resemblence to "Opus from Bloom County"?(one of my fave comic strips)

Cheers,

"007" · 10-02-2006, 01:04 PM

Thanks for the post Dave now maybe I'll get mine from cutting out all the time.

Mahlon · 10-05-2006, 09:48 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by park_ridge_dave:
<snip> And say Mahlon, did anyone ever tell you that your picture bears a strange resemblence to "Opus from Bloom County"?(one of my fave comic strips)

</div></BLOCKQUOTE>
Ackphht! Grbl ngzzs phbltz phlegght!