Using same antenna for scanner and CB?

[redferrariowner]

Basically, I have a scanner attached to a 3 foot Firestik antenna on my car, now I want to get a CB, I believe this antenna works for CBs too. Is there a way to connect both scanner and CB to the one antenna? Would it cause too much interference? Should I buy a seperate antenna?

 

[Bucko]

The answer is no at the same time, your CB transmitter would a number on your scanner. Why not use the Firestick for the CB then get your self a nice scanner antenna.

 

[Raven95150]

While it would be possible to connect both radios to one antenna using adapters, it would not be a good idea, You would probably wreck the scanner if you transmit on the CB. My guess it the Firestik is a CB antenna so thats what you should use it for, it is designed for CB frequencies. (26-27mhz) You shoud get a different antenna for your scanner that is designed for the frequencies you want to listen to.

 

[redferrariowner]

I thought the description on the firestik said it was a scanner antenna, I get great reception on all the frequencies in my area. But if transmitting through the same antenna could damage my scanner then Ill get another one, thanks for the help!

 

[Don_Burke]

I thought the description on the firestik said it was a scanner antenna, I get great reception on all the frequencies in my area. But if transmitting through the same antenna could damage my scanner then Ill get another one, thanks for the help!

Perhaps it gets great reception on all of the frequencies you have tried.

Around here you could form a pretty high opinion of a coathanger if all you were after was Virginia Beach and Virginia State Police.

Can you find a model number on it? The Firestiks I am familiar with are CB antennas.


Edit:

Upon further review by the replay official:
http://www.rfwiz.com/FireStikScannerAntennas.htm

 

[W4KRR]

I've never seen a CB antenna that doubled as a scanner antenna, or a scanner antenna that you could use to transmit on CB with.

CB is around 27 MHz; most scanners cover from 30 to 900+ Mhz, so a CB antenna might provide good results on the VHF low band (from roughly 30 to 50 MHz), but the farther away from 27 MHz you get, the worse the CB antenna will perform for VHF/UHF scanning purposes.

In short, keep your CB antenna separate from your scanner antenna, and mount them as far apart on the vehicle as possible.

In case you ask, the Larsen 150/450/800 is a good mobile scanner antenna, only about 16 inches tall, works well on VHF through 900 MHz bands.

 

[Raven95150]

Around here you could form a pretty high opinion of a coathanger if all you were after was Virginia Beach and Virginia State Police.

A few years ago, I worked for Airborne Express, (Now DHL) the antenna broke off on my truck, so obviously the radio wouldnt work. It was an NMO mount and the whip broke out of the middle of the mount...I straightened out a paper clip and shoved in there with a little tape to hold it in place. It actually worked better than the original antenna. :lol:

 

[n5usr]

I too would suggest a separate scanner antenna. However...

You actually could connect the two radios to a single antenna, if you used a diplexer (some manufacturers call them 'duplexers', but an actual duplexer is something else) like - a quick example - the Comet CF-360A, which will split the antenna port into a 30MHz and down, and a 49Mhz and up port. Put the CB on the low port, the scanner on the high.

http://www.cometantenna.com/products.php?CatID=1&famID=6&childID=0

Some problems with doing this though.

First is simply that these things can be expensive - you could spend $70-75 on the diplexer, while a scanner antenna would be cheaper.

Second is the frequency range of the high port. The 360A only lists 49-470 MHz, so if you are listening to 800MHz trunking it may attenuate the 800MHz signals too much. There are all kinds of split ranges, so you could look through the manufacturers' catalogs and see if there is one that would work for you.

Third, if you happen to want to receive some low-band signals on the scanner but the diplexer's high port cuts off above them you will not hear them.

You also mentioned you thought this Firestik is a scanner antenna. Is it a combination scanner/CB antenna? You may damage the traps (as mentioned on the link Don_Burke posted) if you transmit on it and it isn't designed for that.

 

[52to12]

Back in the late '70s Antenna Specialists made 4 different couplers for CB antennas:
27MHz CB/AM-FM.. VHF HI-BAND/AM-FM, VHF-LO-BAND/AM-FM and UHF/AM.
I still have the CB/AM-FM. I used it for my CB and Bearcat III. It was ok for monitoring. As soon as I keyed the mike it backfed through the scanner.Looking at the instructions today only an UNGROUNDED antenna may be used. I know now that I was using a trunk mount.Maybe that was part of the problem.

 

[Seminoles]

I thought the description on the firestik said it was a scanner antenna, I get great reception on all the frequencies in my area. But if transmitting through the same antenna could damage my scanner then Ill get another one, thanks for the help!

Firestik dose make a fiberglass scanner antenna that is what you might have they are also getting into 2 meter. Forget about keying up a CB with the scanner even on a separate antenna you would overload the receiver in the scanner and with any power added to the CB you would blow the diodes you could use a keying relay like the old tube amps used and wire it to turn the scanner off just before keying the cb a lot of work just use one at a time just think about the cops they have vhf or uhf a computer cell phone/nextel and now homeland what ever there area is using. Talk about getting busted for talking on a cell phone wait until they see two or more radios. ;o) I use a CB antenna dipole on my scanner and pick up 800 and 900 mhz from across the state had to make it into a beam because of adjacent channel interference the good thing about a receiver only is you can use a long wire antenna with out having to tune it.

 

[n5usr]

Forget about keying up a CB with the scanner even on a separate antenna you would overload the receiver in the scanner and with any power added to the CB you would blow the diodes you could use a keying relay like the old tube amps used and wire it to turn the scanner off just before keying the cb a lot of work just use one at a time just think about the cops they have vhf or uhf a computer cell phone/nextel and now homeland what ever there area is using. Talk about getting busted for talking on a cell phone wait until they see two or more radios.

Eh? Where do you get this idea? Yes, if he hooked the two together without proper isolation keying the CB could/would damage the scanner. But with separate antennas or proper isolation (diplexer or such) he'll be just fine. Four watts from a stock CB isn't going to damage much of anything that's on a separate antenna. It might desense the other receiver while transmitting so it doesn't hear as well, but once you stop transmitting the receiver will be fine.

Heck, I run multiple antennas / radios on my vehicles all the time, transmitting 50W VHF and 100W HF and my other radios survive just fine. All on at the same time. Space the antennas sensibly and no problem - just don't mount them two inches apart. (This would affect their radiation pattern as well, so there's more than one reason to space the antennas out.)

Same thing for a single antenna - I know of many installations that use a multiband antenna and a diplexer to combine multiple transceivers on a single antenna run. They all work just fine - even better, since the other ports' RF is blocked on a given port one radio is still able to receive just fine while another is transmitting.

 

[KevinTheMule]

I have a short mag-mount Hustler CB antenna I bought back in the 1990's that works fine as a mobile scanner antenna. The whip is about 2' tall (if that) and has an inch or so coiled load about 4" from the base. Despite contrary advice, I wanted to try it because anything had to be better than a stock duckie inside the car. I just put a BNC on the RG-58 to see what would happen.

It does fine with 800 MHz agencies within a 20-30 mile radius...it really pulls in conventional systems surprisingly well. I haven't done any tuning calculations, but it really sings with the TRACON freq's in my area.

FWIW, it was only a so-so CB antenna...the only reason I initially bought it was because at the time I drove a "fleet" company car (and rentals) a bunch, so I put together a simple CB rig I could take in and out of multiple cars quickly.

I have it on a commute care I drive 30 miles each way to work...it pulls in everything I need to listen to scanner wise...I could also plug it into my handheld CB I keep in the emergency box in the trunk...just in case neither of my two cell phones work .

 

[redferrariowner]

Yeah, the firestik I have is a 24-1200mhz scanner antenna. It sounds like everyone has a specific frequency range they listen to. I live in southeastern Connecticut. Many dispatch centers operate on the 30-40 range, then some in the 140-150 range, one uses a frequency in the 400 range, and really only cops use the 800 range, so you really cant use an antenna specifically tuned to a certain range.

It sounds like the easiest and cheapest way to do this is mount an antenna on each side of my vehicle, thanks again for the help!