Antenna Splitter

Anyone using an antenna splitter, using the cb aerial for the radio?

Any good? Signal degraded at all?

hooo... didnt know that even existed!
would be interested to know as I dont have a radio aerial.....just CB

CB radios operate around 25 - 30 MHz

FM Radio is around 88 - 108 MHz

A CB antenna is tuned for receiving 25 to 30 MHz

A FM antenna is tuned for receiving 88 - 108 MHz

Fundamentally it would work, but, it wouldn't be very good reception and could (though very unlikely due to filters) cause interference to the CB.

Just buy a flexi FM antenna and mount it on the opposite side of the vehicle to the CB antenna

found this?

Zetagi DX27 CB Radio/Car Stereo Splitter Box

Hmm... i think i might bring my CB antenna into work and do a bit of measuring to see what the frequency range of it is then. Theory dictates what i said. But then if aerials aren't highly tuned it would work.

You'd still get signal degregation though. Bit like using one TV aerial at home for multiple TV's

I got one from the LR show,from Thunderpole I think. It's an italian thing,but seems to work ok.

I thought tuned length was more relevant to transmitting rather than recieving though?

isnt the receiving frequency range done by filters in the CB?

[JP];1337733 said:

found this?

Zetagi DX27 CB Radio/Car Stereo Splitter Box

Click to expand...

Hey JP, yep that's just like one I looked at. Made for the job it would seem. But I also wonder about signal degredation, which is why I asked if anyone has experience with one. Sems to work for Harleyman, and from a CB specialist too.

i'm looking to run two ariels for my CB

are there any splitters out there for linking 2 ariels to one cb


or is it a bad thing to do that???

discoboy84 said:

i'm looking to run two ariels for my CB

are there any splitters out there for linking 2 ariels to one cb


or is it a bad thing to do that???

Click to expand...

Why?
Just SWR it - if its OK - then its OK.

incase i loose an ariel off road etc

mine are on my roof bars

just carry a spare magmount.

Or mount it properly?

discoboy84 said:

i'm looking to run two ariels for my CB

are there any splitters out there for linking 2 ariels to one cb


or is it a bad thing to do that???

Click to expand...

Yes, it's called a combiner. Would work, as said, no major benefit really, but if you want to do it, do it

bear in mind that if yu are picking up the signal in two positions, there is going to be an out of phase element to the signal that the CB receives causing distortion and bad signal reflections.

The emergency services spend millions to eradicate this problem.

i'll leave it as it is


cheers

Bump said:

CB radios operate around 25 - 30 MHz

FM Radio is around 88 - 108 MHz

A CB antenna is tuned for receiving 25 to 30 MHz

A FM antenna is tuned for receiving 88 - 108 MHz

Fundamentally it would work, but, it wouldn't be very good reception and could (though very unlikely due to filters) cause interference to the CB.

Just buy a flexi FM antenna and mount it on the opposite side of the vehicle to the CB antenna

Click to expand...

CB aerial works very well for FM reception, the antennae tuning is only important for cb transmissions, as a receiver aerial, just about anything other than a length of wet string will be sufficient.

If you do use a splitter to serve both, make sure you get an auto-switching version (or you will be pumping almost 4 watts of cb power up the rsend of your domestic radio, it won't like it,) or, make your own. Any splitter will effect your SWSR (standing wave to signal ratio) though not usually too badly.

Bump said:

Hmm... i think i might bring my CB antenna into work and do a bit of measuring to see what the frequency range of it is then. Theory dictates what i said. But then if aerials aren't highly tuned it would work.

You'd still get signal degregation??? though. Bit like using one TV aerial at home for multiple TV's

Click to expand...

Signal degradation depends on a number of factors. As for the freq range of your antennae simply measure them and Google for the equation to calculate it's frequency. For a full wave antenna (approx 108" inches,) half wave (54",) quarter wave (27" hence the name DB27,) one eight wave (13½",) rubber duck (6¼") etc. etc.

Also depending upon which band you are using, the old 27/81 (27 megahertz which was legalised in February 1981) or the newer band CEPT - the european frequencies legalised in 1997 (I think it was) the CEPT freqs are lower than the 27/81, and therefore (ideally) should use a very slightly longer whip.

discoboy84 said:

i'm looking to run two ariels for my CB

are there any splitters out there for linking 2 ariels to one cb


or is it a bad thing to do that???

Click to expand...

Disco boy, what you are looking for is called a twin trucker, they usually come with firestick type whips (the thick rigid ones.)

A twin trucker set-up will not increase the output of your set, but what they
will do (if correctly set up) is effect the shape of the transmitted signal.

A pair of twin truckers, set 8' (yes minimum of eight feet) apart, will throw the signal forward and backwards more than side to side. Imagine an egg timer with the two twigs at the narrow bit, the glass of the egg timer is roughly how your signal would be transmitted. What you might gain on frontward (or rearward) tx range you lose drastically on your side ward direction. This happens to be why they are referred to as Twin Truckers, truckers often use this technique for transmitions on highways which are generally in a (reasonably) straight line.

P.S. You can mount as many aerials as you wish, simply use an inlibe antenna switch, you can get one to switch as many aerials as you would ever need (within a sensible limit,) certainly I have seen some that switch up to 5 aerials, they come in rotary or push button types.

Bump said:

Yes, it's called a combiner. Would work, as said, no major benefit really, but if you want to do it, do it

Click to expand...

I have to disagree, there is a major benefit in the directional signal. But for the reason Discoboy wants it, I would advise against it.

The twin-trucker set-up is basically two matched & tuned antennae on a tuned coax which is in the shape of a Y (it is dead easy to make your own, but both branches of the Y have to be exactly the same length.) Then using two exactly matching bases attach your twigs. Set up your SWSR by tuning the twigs etc.

See the problem?

Lose a twig and your SWSR goes out the window big style, you would risk damage to the output stages of your transmitter if you lost one. One of the rare occasions where a wet bit of string would probably be more efficient.

As for distortion etc. that is a fallacy with cb. The output power of the emergency services is much higher than the 4 watts allowed to cb frequencies, your rigs will say 4 watt Tx power, but in reality they seldom put out more than 3.2 watts............. Yes they can be fine tuned to kick out nearer the full 4 watts, but the rig that goes much over 4.5 watts (as most people claim they had theirs tweaked to give out 6 or more) is a very rare item these days. Many unscrupulous "rig doctors" would simply turn the output meter up to make the needle whack of the end of scale and say - there you are mate, I got it up to almost 6 watts - that'll be a tenner.

The old Amstrad 901 cb was the best rig for this. Sadly they are very rare now, but, they can, in fact be altered to go as high as 8w and in some cases 10w, but if you get it up this high, your antenna has to be absolutely perfect or the rig will burn out. One of the ones I had in my possession I had rebuilt when someone burned a hole in the PCB about the size of a 2p coin. I think it might be the one I still have actually.

If you want a bloody good rig, get a Uniden based rig. They are superb sets, but, the sound quality of them is often a bit dull or bassy and are better suited to women with their higher pitched voices. My own personal preference is for either the Amstrad (for sheer flexibility in things you're not supposed to do with them) or any good Cybernet based rig.

But for God's sake, steer clear of Maxcoms - I know of a great many which cannot be repaired (including two I recently threw in the bin.) They did update the set a few years ago and changed the colour of the screen. I think it's the green screened ones you want to avoid, the orange screened ones are ok.