Unusual problem (I think). Any advice appreciated.

[fastSVT]

I've had dual RadioShack mirror mount antennas on my truck for awhile now. Everything was great. SWR was about 1.5, and I could transmit and receive great distances. But during a bad storm recently, a piece of debris hit my truck and snapped one of the antennas at the very bottom, right above the bracket. So I go to RadioShack to get a replacement antenna and put it on. Now I'm not picking anything up except noise. And here's the weird part, when a vehicle passes me on the road...I can hear their engine through my radio?!?!

Here's the antenna setup I have:

[LINK POSTED BY MEMBER] Only Members Can View This Truck Forum Link.

Here's what I replaced the broken one with:

[LINK POSTED BY MEMBER] Only Members Can View This Truck Forum Link.

All I did was go into the store and grab that antenna because it looked like the ones on my truck, but the description on the website says it for single use. Is that maybe what my problem is? Without the new antenna on, I can pickup other radios, but not as well as with both. But like I said, when I put the new antenna on, I'm picking up all kinds of strange noise!

My SWR on ch1 is around 1.7, channel 19 is around 1.3, and channel 40 is like 3.5??

Can somebody lend me some advice? Thanks

[thetez]

theirs either an easy fix or a "what the heck is going on?!?!" you can check the SWR so you might just need to tune the antenna... the one since the original antenna cant be tuned.... maybe if you think they will let you return it (if you dont need it) buy a 2nd tunable one like the original you have, i wouldn't spend more than 20 bucks on an antenna though when you can get a $20 wilson silverload. but try tuning the antenna that can be, the antennas right now arnt matched, if you cna find the right "length" maybe it will fix your problem

[2xR]

Have you checked the nylon insulator that rest in the bracket? If it was damaged when the antenna snapped it could be your problem. It has happened to me several times. I thought it worth mentioning.

[kd5drx]

Originally Posted by fastSVT

I've had dual RadioShack mirror mount antennas on my truck for awhile now. Everything was great. SWR was about 1.5, and I could transmit and receive great distances. But during a bad storm recently, a piece of debris hit my truck and snapped one of the antennas at the very bottom, right above the bracket. So I go to RadioShack to get a replacement antenna and put it on. Now I'm not picking anything up except noise. And here's the weird part, when a vehicle passes me on the road...I can hear their engine through my radio?!?!

Here's the antenna setup I have:

[LINK POSTED BY MEMBER] Only Members Can View This Truck Forum Link.

Here's what I replaced the broken one with:

[LINK POSTED BY MEMBER] Only Members Can View This Truck Forum Link.

All I did was go into the store and grab that antenna because it looked like the ones on my truck, but the description on the website says it for single use. Is that maybe what my problem is? Without the new antenna on, I can pickup other radios, but not as well as with both. But like I said, when I put the new antenna on, I'm picking up all kinds of strange noise!

My SWR on ch1 is around 1.7, channel 19 is around 1.3, and channel 40 is like 3.5??

Can somebody lend me some advice? Thanks

You have 2 options here. tune the one you put on as a replacement since it is tunable and the others weren't. or go back and take the one you bought as a replacement and exchange it for one just like the other one non tunable. The problem is you have mis matched antennas in the same system which will work but not as well as a matched set. hope this helps.

[fastSVT]

Hey thanks guys. I kinda though it was something to do with them being mismatched. And thanks for the nylon insulator comment. I'll check that 1st thing. So how do I tune the antenna? I know you're supposed to cut the steel ones, but what about the fiberglass?

[kd5drx]

Originally Posted by fastSVT

Hey thanks guys. I kinda though it was something to do with them being mismatched. And thanks for the nylon insulator comment. I'll check that 1st thing. So how do I tune the antenna? I know you're supposed to cut the steel ones, but what about the fiberglass?

One of two ways with out seeing it i would say on the top it will have a cap made of rubber usually. You take the cap off and look at the tip it should have wire wrapped around the fiberglass and a coating over it. You can do the next step several ways but the way i suggest since the one is not tunable is to start with your base line like you said its higher on 40 then on 1 you need to trim it a little bit at a time no more than 1/4 inch at a time and then check your swr again. And keep going till you get it to some where close to equal all the way around the dial it may not be 1.1:1 but as close to that as you can on all channels. Once you get it where you want it replace the rubber tip and i always tape them back on so they are for sure watter tight. Hope this helps. If it has a sliding collar on it some place that would be the other way. Or it may have a screw in the top with a lock nut on it like some of the Wilson's do so just look it over good. to start with and you should be fine.

[fastSVT]

Ok I don't see how I'm supposed to tune this thing. I took the cap off, and there's no wire exposed.

One of the reviews on RadioShack says "it can be adjusted at base"??

[fastSVT]

PS: The nylon insulator is fully in tact.

[thetez]

ah... my buddy has one of those..
and its really not much of an adjustment, their was a bolt or something .. allen key? that needs to be loosened then the whole antenna can slide up or down, i didnt get it to make much of a diffrence when i tried tuning for him, we tried my wilson silver load, it was much better, so he just ended up buying one of those. but thats how, the entire thing slides up and down...

[fastSVT]

OK I found it. It's a flat-head screw inside the rubber cap. After a little tinkering, I got ch40 to abou 1.4, ch 20 at around .9, and ch1 around .3. That confuses me though because I thought channels 1 and 40 were supposed to be higher than 19???

Anyway, it seems like unless I keep my RF gain below halfway, my meter is picking up too much noise. Doesn't seem like it did that before?