Antenna Tuning

JeepinJarhead03 · **Posted:** Thu Apr 02, 2009 4:13 pm

hrmph

sounds like you've got something thats touching the body that shouldn't be and that 2.5 on 1 and 40 is where youre swr actually 'is'

I would try it without the spring but with the QD and see if it's still high, then maybe try it with the spring and not the QD

i had a cam type QD, the kind that has the 2 studs that stick out into a slot, and it made my SWR 0.8 higher than my WQD fat ham antenna type QD

it certainly sounds as if you've got a component problem and unfortunatley when you're working with like 4 watts , 20% is alot of loss and thats completely ignoring service live loss in your radio equiptment

does you or jayme have a multimeter? it makes diagnosis of component trouble easier

lionseye640 · **Posted:** Thu Apr 02, 2009 4:16 pm

No multimeter here

JeepinJarhead03 · **Posted:** Thu Apr 02, 2009 4:22 pm

they aren't required or anything, just sometimes makes it easier to figure out where to start, i'm sure yall can figure it out by swapping some things around and retesting, it's mostly a process of deduction

unless the antennas are truely toploaders they seem to show short when mounted on the back of the vehicle, the antenna coil needs to be able to 'see' over the top of the vehicle

which in that case, the spring being there should HELP it not hamper it unless the spring has alot of electrical resistance

make sure to let us know what the results end up being

JeepinJarhead03 · **Posted:** Thu Apr 02, 2009 4:53 pm

or if say, the spring is hitting the body of the vehicle or something it would cause the signal to ground and loop

she may also need a new coax stud it could have gotten damaged when the antenna was broken

lionseye640 · **Posted:** Thu Apr 02, 2009 5:13 pm

yellocoyote wrote:

Ann - here's another thought. Did Tim solder the coax to the connector that screws into the radio? I know I had to do that... and if he didn't, that might screw with your reading too.

He didn't solder it.... at least that I'm aware of.

The antenna didn't really break so much - the little rubber cap fell off, then the screw got busted off. The antenna itself was a little beat up, but still in one piece.

JeepinJarhead03 · **Posted:** Thu Apr 02, 2009 5:13 pm

ahh yeah you guys had to deal with the whole unterminated coax to get the coax to the antenna?

messy , i don't like terminating coax, had to do it for a school once, took a week to finish getting the copper splinters out of my fingers

corwyyn · **Posted:** Thu Apr 02, 2009 7:49 pm

lionseye640 wrote:

It's turned out so about 6-8 threads are showing (not 100% sure, KJ is outside, PC is inside). While trying to adjust I'd go 1 turn at a time, then tried less than 1 turn at a time.

lionseye640 wrote:

All I know is that it worked before, was tuned properly at one time, I smacked the antenna on a parking garage, replaced antenna & added spring/quick-disconnect combo, now - 2.5.

OK based on these facts it seems like the spring and disconnect are adding some length to the whole system and you need to shorten it (turn the screw into the fitting). Do you still have it at the point where you where getting 2:1 on ch. 19? If so then you might try going in another turn or two and see what you get; if it keeps going down you know you're heading in the right direction, if it goes back up then you overshot it. As stated a mark on the screw will help with counting the turns, and once you get it under 2:1 on 19 you can try turning it 1/4 turn at a time to see if you can finesse it in to a good reading.

Yes it can be tedious trying to tune it, and a second set of hands will definitely help.

lionseye640 · **Posted:** Fri Apr 03, 2009 1:54 pm

I was just on the Firestik website doing a bit of research and it says that the nylon (white) washer is supposed to have the "raised shoulder" facing the mounting surface. I'm going to go check that on my lunch break, but is the shoulder of the washer the outer edge or the inner edge where the bolt goes through?

lionseye640 · **Posted:** Fri Apr 03, 2009 2:24 pm

yellocoyote wrote:

I would guess that to be the inner edge. I'd have to go look at mine to know for sure.

Eh, I'll just give it a try & see what happens with the SWR. It'll have to wait until I get home though (left the wrench in the kitchen :roll:

)

JeepinJarhead03 · **Posted:** Fri Apr 03, 2009 4:12 pm

the 'shoulder' of the washer is the part seats into the hole in the mount where your antenna stud comes up through, keeps the center stud from touching the mount and keeps the base of the antenna hard ware from touching the mount

in otherwords, theres a 'ring' shoulder on the washer that faces down towards the mount and it snugs into the hole in the mount

corwyyn · **Posted:** Fri Apr 03, 2009 9:55 pm

JeepinJarhead03 · **Posted:** Fri Apr 03, 2009 10:00 pm

just make it upside down from that diagram hehe

JeepinJarhead03 · **Posted:** Sun Apr 05, 2009 8:03 pm

is there any more length left in the tuning screw?

i know with most of the firesticks you can replace the original tuning screw with a regular bolt from lowes or something to get more length, it sounds like your coax fix fixed the swr issue it's just still a little short

JeepinJarhead03 · **Posted:** Sun Apr 05, 2009 10:16 pm

ahh, o well, that tends to happen once one side or the other hits just about dead on 1

sounds like it's good to go now anyway

glad yall got it fixed up!

I know who to come bug now when I have solderin work to be done, cause i solder like a monkey playin with poo

tommudd · **Posted:** Sun Apr 05, 2009 10:18 pm

take the spring out and try it, that will change the SWR and mess you up as well. Springs are great on the trail but not great for trying to tune in your radio

JeepinJarhead03 · **Posted:** Sun Apr 05, 2009 10:23 pm

thats kinda why i went with the flex4 wilson and a FAT quick disconnect

:lol:

not too worried about snappin mine, i guess if i do i'll stick a spring on it along with another flexer

tommudd · **Posted:** Sun Apr 05, 2009 11:27 pm

yellocoyote wrote:

so, if we can bring the swr down more without the spring on... wouldn't that then be bad to put the spring back on and run like she wants to all the time?

cdiekhans was having some problems with his, took it to a CB shop and "part " of the problem was the spring according the the CB guy , after he got the plastic spacer part in the right way, got a Wilson Flex4 and removed the spring everything was good.

DryBones · **Posted:** Sun Apr 12, 2009 10:44 pm

I finished my Cobra 75 install today. using the same Radio Shack SWR meter I had the screw all the way in on my 4' firestick with a HD spring and the bracket mounted along side the flipper glass and was pulling just below a 1.2 on both 1 and 40 and almost perfect 1 on 19! Look out truckers, here I come! How much distance should I expect with this set up? I talked to a trucker about a mile out after I was done but it was almost a clean line of sight between us.

JeepinJarhead03 · **Posted:** Mon Apr 13, 2009 2:25 am

it varies a lot on who you're talkin to, where they are and where you are but with clear line of sight you can get about 10-20 miles at 4 watts with no skip

due to the nature of the AM beast, they work the best during the day when the atmospheres radiated but we're still at minimum sunspots so I've not managed to talk much skip except right before thunderstorms

LibertyFever · **Posted:** Mon Apr 13, 2009 9:14 am

WoW, I'm surprised something as simple as tuning a CB antenna could turn into a three page posting. But then again, it is one of those things that's difficult to explain via text.

I must confess that I didn't read each reply so forgive me if I'm repeating somebody else's reply.

My understanding of the principle of a magnetic mount antenna is that it's a base loaded antenna that must be mounted in the center of the roof panel for best performance. All too often I see it stuck anywhere there's a metal surface, on top of a fender, on a hood or a bumper.

I have a K30 mounted on my roof and get pretty fair SWR numbers from it on the lower part of the CB band. Seriously when you go off road the most common channels you will use are channel 4 and 16 (4 x 4 = 16).

Antenna Tuning

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