Standard SS 102-inch whip - spring or no?

[JamesPrine]

Hello all!

I just bought a brand-new Uniden PRO538W CB transceiver from a colleague; he threw in a still-in-the-shipping-tube 102-inch stainless steel whip antenna from Radio Shack. Not a bad deal for $30 total...seems he bought this stuff on an impulse and his wife freaked, hence the quicky sale and minimum doghouse downtime for my colleague <g>.

I was going to craigslist or eBay the gear but now I want to keep it. I'm restricted to using a magnetic mount antenna installation as opposed to any other mounting system, and I will be using the 102-incher atop a Minivan.

LOL, I know, the "radio control car" image, but this is for working at an airport so being cool, chic and trendy isn't part of the equation anyway.

My question is this: I know many people insist on equipping their 102s with heavy-duty 6-inch SS springs, mainly to lengthen the overall antenna length to a full quarter wave at 108 inches.

Others say that the spring is a worthless gimmick and that it wreaks havoc with SWR settings both when tuning and when actually operating the radio while in motion and the antenna whip is flexing around more than normal due to the spring's activity.

One more question: I intend to attach the 102 to one of those heavy-duty 3 x 5-inch magnet mounts such as the nice one put out by Tram. Do you guys think that will be reasonable for a 102-inch whip? Remember, this will be used atop a minivan, not an Aston-Martin performing odd deeds for Her Majesty's Secret Service.

Any comments, questions, or advice to seek a psyche consult?

Thanks for any input!

 

[CompuDoc]

I am wondering how many cable tv, telephone and power lines are you going to be hitting with the antenna on the roof of the mini van and if your hitting those wires will the antenna stay in place. Figuring that the mini van is about 5 foot high (guessing the height) with the 102" whip that would put that 13' 5" in the air and then add the 8" for the spring if you do go that route and you may need to for the swr's to be in a good area then your talking 14' 1" tall. Now recently I seen a trailer from a tractor trailer that was 14' high going down a road as I was following him and he was barely missing the wires. He got to one point in the road and actually took the telephone wire down leading to the house from the pole across the street and kept going.

Now I am not saying an antenna will take down the wires if it were to hit the wires but if it did hit the wires it might hit with enough force to loosen the base of the antenna and have it roll off the mini van and perhaps even hit the person who is driving behind you. It might be something that you want to consider. What I would do is get a fiberglass wire wound antenna that is a bit shorter. I had an old Cadillac Ambulance that had a ball mount on the fender for a 102" whip antenna and I had a wire wound fiberglass antenna on it that achieved a better SWR than the 102" whip did with or without the spring. The fiberglass wire wound whip was about 5' tall and I used it without the spring.

 

[freqs]

One thing to check is not all mini-vans are made of a all metal product so grounding could be a issue .
The city of Sterling Hgts had a issue bck in the 90"s with the PONTIAC and Chevy MPV Lumina's they had to put in supports and ground straps to mount their antenna's on the roof .
Another thing to think about is if you put the 102 in whip on the top of you mini-van it will hit alot of stuff
I had a wilson 1000 ontop of my 2500 hd and it hit all the tree branches over hangs at the drive-ins and at the bank .Now take this how you want what I would do is get a Wilson or a smaller mag mount antenna that whip will end up being a big pain up that high just my 2 cents plus what you spend on a good mag mount for the 102 you coud get a antenna that dont look as silly as a 102 on top of the mini-van iam not attacking your idea the 102 and how it looks but if you like that look go for it.

 

[JayMojave]

Hello James Prine: These are all good questions:

The 102 inch stainless steel whip antenna will work well on top of your mini van, but you will need a three or four of the magnet mounts tied together to keep it on the mini van. There out there at CB and Ham radio shops.

Also the 102 inch whip antenna being tall, you will hit every low lying cable, tree branch, and anything else that isn't kept out of the way. I believe I have hit things that I couldn't even see durning the night.

I had a 102 inch whip antenna on my 1977 Ford F250 4X4 Truck that sets up pretty tall from the factory and has a set new modern tires and rims. I got tirid of hitting evey low lying thing, and installed a Wilson 5000 Antenna and then a custom made 72 inch whip antenna with a base matching coil. The 72inch antenna usually miss's most all the low lying things so I not hearing a big Coo-Gong in the cab every time I hit some low lying TC Cable. And works just as well as the 102 inch whip antenna.

The advantages of the tall boy truck is helping lady friends in and out of the truck!

The Wilson 1000 or the 5000 mobile antennas aren't cheap but they work well.

Please let us know how you make out. Good luck.

Jay in the Mojave

 

[GROCKSHD]

Use a spring, your gonna need it to release some tension and help keep the whip from being ripped off the vehicle, especially since you are going to be hitting everything

 

[CompuDoc]

I do not know if they are made not anymore or not but another good antenna was the K40 and they had a magnetic version. I had an Antenna specialist antenna on my 1985 Pontiac Fiero GT and the SWR's were to high. I then put on a K40 antenna and the SWR's were very good. The difference was the K40 antenna was machine wound by a computer controlled machine as opposed to being hand wired in the coil.

The Pontaic Fiero was a fiberglass outer body but a full frame underneath. You could actually take all the body panels off and drive the car down the street and still be wrapped in a steel frame. Similar to a roll cage in a race car but with more metal. It was mounted on one of the two metal grill vents behind the rear window and was held in place by a hose clamp. Then I ran a ground strap from the thumb screw that held the grill in place to the frame and it worked fine. I had the antenna specialist CB antenna mounted the same way including the ground strap and the SWR's were still to high.

 

[mrweather]

1/4 wavelength for 11 meters is about 108". You'll still need that spring to make the antenna the proper electrical length.

 

[JamesPrine]

Hello all, and thanks sincerely for all the helpful comments!

This minivan will spent 95 percent of its life sitting adjacent to the administration building and general aviation ramp at an airport. In that location, it will not be a matter of the antenna hitting something, but something hitting *it*...a bird or an aircraft, and if an aircraft hits it, I don't want to be inside the minivan anyway <wink>.

We wanted absolute maximum range for the installation and no hassles with coils, etc. Using a K30 at present but it's not entirely satisfactory.

I was opting for the spring but did not want SWR problems.

My colleagues and I are thinking of the Tram 3-magnet mount and possibly some sort of quick release for the 102" whip itself, something that will not alter the SWR or compromise the structural integrity of the mounting system; "the boss" thinks we can unscrew and stow the 102 whip at the end of the day and for occasional trips to the service station, fuel, errands, etc.

 

[N_Jay]

I good spring will have a piece of braid inside to "short out" the spring coil and prevent issues with noise and SWR.

Metal whips need are usually 102" and need the spring.
Fiberglass whips may or may not depending on how they are made.

 

[prcguy]

Stick a spring on it as a little insurance and you can easily grab the entire 3 or 4 magnet mount with whip off the roof and stow it. I occasionally run a 4 magnet mount with a 7-8ft hamstick and its not difficult to grab the antenna at the spring and yank it off the vehicle.
prcguy

 

[XTS3000]

1/4 wavelength for 11 meters is about 108". You'll still need that spring to make the antenna the proper electrical length.

Yep, exactly. In order to get the lowest SWR and highest performance the 102" SS whip was designed to be used with a spring.

 

[talkpair]

Another thing to consider is garage clearance.

My 12" Maxrad gmrs antenna will make you think the whole house is falling in on you if you forget to remove it from the roof before pulling into the garage.

It's mounted on the cab of a Ranger pickup.

 

[JamesPrine]

The 102-inch whip is installed and atop the airport minivan. It is attached to a *very* heavy duty stainless steel spring which happens to be 4 inches in height; I never could find a stainless steel pot belly spring 6 inches long.

C'est la vie.

This contraption is attached to a Tram Tri Magnet roof mount (wow, this thing is really nice and excellent quality!); overall, it looks pretty impressive.

Got the transceiver powered up and WOW! What a difference between the K30 and this monstrosity! With the K30 I couldn't receive any of the NOAA weather channels even with RF gain at max and squelch turned to minimum, with the SS whip attached, the reception is full quieting on 2 out of the 3 channels we have in range round here.

Roaming the various channels, it is apparent that reception is several orders of magnitude greater than the K30 at its best. A radio check assured me that the signal is easily making it to Interstates 12 and 55 a few miles away.

This is definitely a keeper of an antenna setup and I and my troops are very happy with it.

P.S. - The "redneck factor" isn't as apparent as we had dreaded; I actually like the new antenna and most people round here just assume it's a new aeronautical gizmo and mostly ignore it.

Thanks guys!

P.P.S. - No, this is NOT an April Fool's Day joke.

 

[hockeyshrink]

The 102-inch whip is installed and atop the airport minivan. It is attached to a *very* heavy duty stainless steel spring which happens to be 4 inches in height; I never could find a stainless steel pot belly spring 6 inches long.

C'est la vie.

This contraption is attached to a Tram Tri Magnet roof mount (wow, this thing is really nice and excellent quality!); overall, it looks pretty impressive.

Got the transceiver powered up and WOW! What a difference between the K30 and this monstrosity! With the K30 I couldn't receive any of the NOAA weather channels even with RF gain at max and squelch turned to minimum, with the SS whip attached, the reception is full quieting on 2 out of the 3 channels we have in range round here.

Roaming the various channels, it is apparent that reception is several orders of magnitude greater than the K30 at its best. A radio check assured me that the signal is easily making it to Interstates 12 and 55 a few miles away.

This is definitely a keeper of an antenna setup and I and my troops are very happy with it.

P.S. - The "redneck factor" isn't as apparent as we had dreaded; I actually like the new antenna and most people round here just assume it's a new aeronautical gizmo and mostly ignore it.

Thanks guys!

P.P.S. - No, this is NOT an April Fool's Day joke.

Sounds very cool James... I'm glad you are happy with it!

A lot of folks now seem to be running the Wilson 1000 antenna on a mag mount, rather than the K30 or K40. (I have a K40 in the garage, it was a good antenna back in the day)

Found a spring on ebay, should you still be looking for the 6". I use this heavy duty Procomm spring when I run a whip.

Procomm Heavy Duty Barrell CB Whip Spring - eBay (item 320474393572 end time Apr-13-10 10:49:10 PDT)

 

[k9rzz]

Excellent! Go BIG or go HOME! LOL

 

[kc2rgw]

Spring for CB, no spring for 10m. The spring drops the resonance down into the CB band a bit more. Without it, it's centered a bit higher up into the 10m band.

You don't really need the spring for protecting the antenna, but beware how sturdy a mount you have, particularly on the top of a van. I'd consider a shoulder plate of some sort inside the sheet metal, particularly if you don't put the spring on it.

 

[JamesPrine]

The 4-inch SS heavy duty spring is doing the job nicely; I think the other two inches is pretty well accounted for in the beefy Tram Tri-Magnet mount. The other night I did a little radio check on CB Channel 10 with a base station approx. 16 miles away and he said I was 'lima charlie', so I'm satisfied with the CB performance.

As for 10 meters, I have yet to get another transceiver for that but will keep the 'remove the spring' tip in mind.

I'm still astonished at how my scanner picks up new frequencies I didn't even imagine were out there, thanks to the monster whip.

Scanning is FUN again!

 

[kc2rgw]

If you put an analyzer on it, you'll see it's very broad banded re: the 102" whip.

It isn't totally necessary to move the spring in and out, but a basic tuner would make the radio happier.

I run it just for 10m mobile so I wanted it as centered on the band as I could get it and it makes a fair diff, particularly since 10m FM repeaters are nearly at 30MHz and SSB is down in the middle of 28MHz, it's quite a big band.

 

[KF4ZTO]

RS makes a 102 inch whip for use with the spring, MFJ makes a 108 inch whip for use without the spring (resonant at 26MHz, which works nicely for 6 meters....since its a half wave at 52MHz).

I put my MFJ 108 inch whip on a spring and use it to scan VHF lowband...works amazing.

Perfect SWR on 11 meters as well.

 

[mrweather]

If it's a 1/2 wave on 6 you'll need some sort of matching network because the feedpoint impedance will be extremely high.

Otherwise yeah, good for 11, 10 and low-band listening.