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Antenna questions

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Stevo02TJ
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Joined: 02 Jan 2005
Location: Waynesboro and Harrisonburg, Virginia

PostPosted: Sat Sep 17, 2005 9:57 am    Post subject: Antenna questions Reply with quote

Hey, I have a few questions about my antenna.

To start, 1fox2go and I were on the trail, and whenever he would speak, I'd get a mid-range "buzz" instead of his voice. He could hear me loud and clear, but all I would hear is this buzz. What causes that?

To try and fix it, we put another one of his antennas on my antenna mount, and it was working alright.

I also don't like the output of my FirestikII 3-footer, so I was thinking about a K40. I've got a Radioshack TRC-503 Mini Mobile CB Radio, 20 feet of RG-58 Cable, and a FirestikII 3ft. antenna.

My last question is which would work better, a K40 3' or a K40 4' antenna? Is it obvious that the 4' will work better?
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ThePhantum
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PostPosted: Sat Sep 17, 2005 12:01 pm    Post subject: Reply with quote

It sounds like that firestik might have a problem. Where is it mounted? How much of the antenna is above the ground plane of the Jeep? Was the antenna you swapped in longer, shorter or the same length? Was it bottom loaded (a whip ) or top loaded (like a firestik)?

I would put an SWR meter on it and make sure standing wave is within limits (preferably 1.5 or lower). It could be that the antenna you swapped in was tuned better with the ground plane of the Jeep. 20' of cable huh? How is that cable run? If it's coiled up someplace (RF choke) that can cause all kinds of wierd things to happen.

Generally speaking, top loaded antennas (like Firestiks) perform better than bottom loaded ones (like K40 whips). At the same time, the longer the antenna, the better. So switching from a 3' firestick to a 4' whip will most likely be a marginal (if any) gain.

As far as output, the 3' Firestik is rated at 300 watts (the 3' Firestick II is rated at 650). Assuming your radio is barefoot, it's only putting out a maximum of 4 watts. Even if you had it tuned, that radio is only going to put out a maximum of 30 or so watts. So going with an antenna with a higher power rating will do nothig for you. Again, check the SWR and get it as low as possible. You'd be surprised how much better an antenna system will perform with a small reduction in standing wave resistance.
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IBTJn
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Joined: 31 Dec 2004
Location: Just Outside of Portland, OR

PostPosted: Sat Sep 17, 2005 4:31 pm    Post subject: Re: Antenna questions Reply with quote

Stevo02TJ wrote:
To start, 1fox2go and I were on the trail, and whenever he would speak, I'd get a mid-range "buzz" instead of his voice. He could hear me loud and clear, but all I would hear is this buzz. What causes that?

To try and fix it, we put another one of his antennas on my antenna mount, and it was working alright.

Sounds like a mic problem on his end to me...not your set up. A simple bad connection or mic going bad can do that...and be sporadic as the connection(s) partially make contact. I had a friend on our last run (dustdriver) whos mic would periodically do the same thing. I asked him to stop, pulled out my back up mic, and hooked it up for him (we both run 4-pin Unidens). Problem solved. I can't ever remember a receive that was effected as you described by the antenna system ??? . Heck, if he's next to you, you should hear him plain as day even on a dead or no coax. That's how I/we used to track people down on the radio (along with a few other tricks). rofl

Stevo02TJ wrote:
I also don't like the output of my FirestikII 3-footer, so I was thinking about a K40. I've got a Radioshack TRC-503 Mini Mobile CB Radio, 20 feet of RG-58 Cable, and a FirestikII 3ft. antenna.

My last question is which would work better, a K40 3' or a K40 4' antenna? Is it obvious that the 4' will work better?

As ThePhantum mentioned, way too many questions I'd have here. Mostly mounting location, mount type/style, etc. Also, the coiling of the coax...absolutely true what ThePhantum said about "choking" the RF signal.

And yes, typically a 4' will indeed out perform a 3' antenna comparing apples to apples. And given the newer heavy top loaded K40's are supposedly 5/8 wave coiled now, they will probably work about the same as the Firestik...although I'd never buy one to try it out. I personally don't care for either of them as I think they are way over rated. But that's just me, and my experience.

Wink
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1fox2go
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Joined: 01 Dec 2004
Location: Fishersville, Virginia

PostPosted: Sun Sep 18, 2005 6:42 pm    Post subject: Reply with quote

If its my radio why did the antenna change work?

mines been working fine ever since i have hooked it up

stevo just keep that antenna it works good dont change the set up you got now
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ThePhantum
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PostPosted: Sun Sep 18, 2005 8:27 pm    Post subject: Reply with quote

IBTJn said it was possible that it was your radio...not that it was definatley the case. Part of the troubleshooting process is to determine any and all potential causes and proceed to eliminate the possibilities until you find the problem.

The fact that he could broadcast means that the original antenna works, so most likely the issue somewhere with his setup and the new antenna is only masking the problem. Continuing to use a system that has shown some faults can damage the radio. So the statement of:
Quote:
just keep that antenna it works good dont change the set up you got now

Is very bad advice IMHO....akin to "ignore the problem and it will go away". Guess what? It won't...it'll only get worse. Wink
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Stevo02TJ
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Joined: 02 Jan 2005
Location: Waynesboro and Harrisonburg, Virginia

PostPosted: Mon Sep 19, 2005 6:19 am    Post subject: Reply with quote

Well, my firestikII had an SWR of 1, 1.2 MAX!! I would calibrate it, key the mic, and the needle would barely move. I did a quick install with the coax, som most of it is laying in the floorboard until I can run it under the Jeep. I have an Arizona Rocky Road Mount as seen here I'm running the single antenna mount with standard connector.

Also, I am taking a wild guess Phantum, but do you know anything about Amateur Radio? I'm thinking about getting a license and mounting a HAM in the Jeep.

Well, for now, that's my setup, I don't know what's going on. Any more help would be appreciated.

(I was on Rt. 29N last night, and I was hearing a trucker loud and clear about 3 miles out Southbound.)
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IBTJn
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PostPosted: Mon Sep 19, 2005 7:30 am    Post subject: Reply with quote

Stevo02TJ wrote:
To start, 1fox2go and I were on the trail, and whenever he would speak, I'd get a mid-range "buzz" instead of his voice. He could hear me loud and clear, but all I would hear is this buzz. What causes that?

To try and fix it, we put another one of his antennas on my antenna mount, and it was working alright.

Phantum is correct...I merely threw out there what it sounded like to me.


Steve02TJ, you should be able to hear him even without your coax installed to the back of the radio if he's within 100' of you or so. Antenna replacement on your rig should have nothing to do with a "buzz" on your receive when 1fox2go talks (or keys up) as your antenna cannot distort HIS modulation...only the signal strength. Or maybe I'm misunderstanding the description/quote listed above???

Based on the description/symptom (listed above) I'd be first focussing on 1fox2go's mic. Simply put, you move the mic around to either talk, set it down, or hang it up while you guys were replacing the antenna. When you return, it worked...thus my conclusion/deduction. It's possible after moving it around, sufficient connection was again achieved, appearing as though making an antenna switch on Stevo's rig solved the problem. When in reality, it had nothing to do with it. Setting 1fox20go's mic down fixed it...temporarily anyway.

If I've understood it as listed, I'd ask the question of 1fox2go's radio/mic model(s) and how long they've been in service? I merely suggested to check that possibility (as ThePhantum said). Move the mic around on 1fox2go's rig. Tug some on the cord while keyed up...as might be done on the trail. As the description I gave with Dustdriver's radio, his SWR's were 1.7:1 (+/-) at the time...not the best, but clearly (to me) not causing the squeel/buzz. It was a mic problem based on the equipment he runs and the sound of the squeel. It progressively got worse over time, too (period of months). Probably a bad connection, but we never bothered to check it as we were on the trail. I just loaned him my back up stock mic. It's worked ever since...which has been since the end of July.

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1fox2go
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Joined: 01 Dec 2004
Location: Fishersville, Virginia

PostPosted: Mon Sep 19, 2005 8:49 am    Post subject: Reply with quote

I have the same setup as stevo and mines actually newer
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ThePhantum
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PostPosted: Mon Sep 19, 2005 9:48 am    Post subject: Reply with quote

IBTJn, that's a good point....I remember a few months back when majikxms and I were scouting a trail, He couldn't hear me at all but I could hear him just fine...so all the symptoms made us think that it was a problem my setup. We checked the antenna (ground, etc.), then put a meter on it and it was working fine. I then flipped on my handheld, and my rig was working...it was his that wasn't getting reception. He uses a handheld with a mag mount antenna, so we just hooked my handheld up to his setup and it worked for the rest of the ride. What's the point? Even though the symptoms seem to point to one rig, it can easily be the other.

Steve, did you check SWR on just one channel or did you check for center frequency dip? Basically you are checking SWR across the entire range of the antenna. To do this you take readings at channels 1, 20 and 40. Channels 1 and 40 should be about the same and channel 20 should be lower (hence, center frequency dip). If there is a difference between 1 and 40, then the antenna is either electrically long or electrically short and needs to be tuned.

As far as Ham radio, it operates on different frequencies than CB does. So a straight CB antenna won't work with it since they are not designed to handle those frequencies (meaning you'll burn out the radio). Still there are some nice mobile ham radios I've seen. I also know that Cobra has recently put some mobile Hams out there that look pretty nice. Expensive though, you are looking at $400+ for one.
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Stevo02TJ
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Joined: 02 Jan 2005
Location: Waynesboro and Harrisonburg, Virginia

PostPosted: Mon Sep 19, 2005 9:56 am    Post subject: Reply with quote

Well, I just checked ch. 19

Thanks for the input, and I am aware that I can't use a CB antenna for a HAM, thanks for the other advice too...now if I could just find a place to take the test (so I'm legal...). Thanks for all the help.
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1fox2go
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Joined: 01 Dec 2004
Location: Fishersville, Virginia

PostPosted: Mon Sep 19, 2005 11:19 am    Post subject: Reply with quote

ThePhantum wrote:
IBTJn, that's a good point....I remember a few months back when majikxms and I were scouting a trail, He couldn't hear me at all but I could hear him just fine...so all the symptoms made us think that it was a problem my setup. We checked the antenna (ground, etc.), then put a meter on it and it was working fine. I then flipped on my handheld, and my rig was working...it was his that wasn't getting reception.
.


thats what stevo had wrong with his, i could hear fine he couldnt hear me, so whos cb is it mine or his?

theres a contradiction here first it was mine now it sounds like his....just need to know so if it is mine we can fix it
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IBTJn
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PostPosted: Mon Sep 19, 2005 1:52 pm    Post subject: Reply with quote

Well being you guys have the same radios, can't you just swap microphones and see if it makes any difference? Shouldn't take but a couple minutes. Try and make it squeel again if you can. (besides, it gets Kizer excited to hear squeels rofl )

BTW, you can indeed use a 11 meter (CB) antenna for 10 meter (Ham). But that takes the General Tech (?) Ham license which requires a minimum of 5 wpm of CW (morse code) plus the larger written exam from the normal "No Code" Tech license...if I recall correctly? But 10 meters is used primarily for DX (skip)...which I'm not sure you are interested in doing (or so it sounds). No code tech uses line of sight and repeaters only...which is considered 2 meter band.

Many of the Ham friends I have/had that used run 10 meters used the SOTT-5 60" Tiger in their mobiles...which is broad banded enough to be tuned from about 27.385 MHz up to 28.5xx MHz or so, with a nominal average SWR of 1.5 or less @ 100 watts PEP. Probably TMI...sorry if that's the case. Embarassed

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Stevo02TJ
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Joined: 02 Jan 2005
Location: Waynesboro and Harrisonburg, Virginia

PostPosted: Mon Sep 19, 2005 2:26 pm    Post subject: Reply with quote

LOL, actually, no it's not TMI. I enjoy learning about the Amateur Radio hobby. I'm hoping to get my technical license for starters, then maybe move up to the next level by taking a 5 wpm morse code test.

Yea, we could swap mics, I also have an extra, I could give him mine and use the extra. (If it's his that is screwing up)
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Stevo02TJ
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Location: Waynesboro and Harrisonburg, Virginia

PostPosted: Fri Sep 23, 2005 12:00 pm    Post subject: Reply with quote

Ok, I went out and fooled around with my SWR last night. I was able to pick up truckers on I-64 about 7 miles away.

This morning, I was at milemarker 96 on I-64, picking up truckers talking about a state trooper at milemarker 221 on I-81. I-81 was over ten miles away...Exit 87 on I-64 is the I-81 exit.

Today, I was seeing if I could improve my SWR, and I got it to where it just barely moves above 1:1. I put the cap on and it jumps to 1.5:1. I have the same setup (other than a 4' FirestikII -- instead of a 3'...same antenna model, etc.)

-Why does my SWR jump to 1.5:1 when I just put the cap on?
-Is there any way around this?
-Does it need the cap?
-Are there substitutes that give better SWR readings?


Thanks,
-Stevo
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Stevo02TJ
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PostPosted: Fri Sep 23, 2005 12:12 pm    Post subject: Reply with quote

Also, I found this pretty neat. A VSWR Loss Calculator
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