Cb Aerial

[Guest docter fox]

its becoming clearer....how do actually physically change the frequency to match the antenna? do you actually lengthen/shorten the antenna?

 

if so i take it you can't you get telescopic antennas?

they seen quite big, how long are they?

 

Getting there

James

[Guest Andybarbet]

Hi Doctor Fox,

Yes, you do alter the length of the aerial to 'Tune it' with the aid of a SWR meter, the aerials have a grub screw at the bottom which allows you to raise / lower the aerial by an inch or so to get it spot on, my sirio 3000 is about 6ft long but is the best aerial i have had for CB, super modulator would be my second choice and they do a nice bayonet quick release for them which is very handy. Should be able to pick up a supermodulator second hand rather cheap now.

 

Hope this helps ?

 

P.S - Just checked out your website doctor fox....Very good, keep up the good work :-)

[Dave R]

a quarter of a wavelength for cb freqs is about 108 inches

you can get antennas this length though they tend to be loaded, (got a coil in them)

the more pysical length thats in the coil the less efficent the antenna is, though for what we need them for it dont matter

when you alter the length, generally you shouldnt have to shorten the whip its self, if its a good design that isnt operating too far from the manufacturers design freq then there should be enuff adjustment with t he grub srew and the hole in the top...

occasionally though and with extra bits of metal next to it, (roll bar) you may have to cut or lengthen the whip

 

 

hope that makes sense

 

dave

[Guest docter fox]

so the antenna/aerial ranges from 6ft to 9ft (108inches) do people keep them permanently on the car? what about putting it in the garage?

 

im like the sound of the unclippable supermodulator one but google just gives me random rubbish where do i get them from?

 

whip? is the the pole type bit of the aerial? what would you use to lengthen it and how would you join it back together?

 

is it best to buy SWR meter or just borrow someone who has one?

 

i thought i understood....not any more

James

 

P.S. - thanks there should be a few more pics to go on soon, iv made the dash, fitted the gauges and just need to put it in

[Dave R]

the whip is the flexible bit, the loading coil is the thick bit

dont bother buying an swr meter, there will be someone in the club nearby with one

[Dave R]

as far as super modulator goes

would look rather big on a hood

and is as far as i remember center loaded (coil in middle with whip either side)

much better with dv27 (all loading coil on a fiberglass former)

or something like a rebel minor or satalite minor

both of the last 2 are about 2 foot long and plenty good enuff for up the road stuff

[Guest docter fox]

plenty good enuff for up the road stuff

how longs the road?

 

how long is the dv27 antenna? if i put it on a mounting plate (like big jim) could i take the plate off and put it back on ok without having to do the SWR'ing?

 

sorry about all the questions but i am getting there

[Big Jim]

both of the last 2 are about 2 foot long and plenty good enuff for up the road stuff

Not on a hood, you get reflection from the roll-over bar, and can't get the SWR down.

could i take the plate off and put it back on ok without having to do the SWR'ing?

A DV27 comes with a wing nut fastening, so if you really want to, you can take it off. Providing that you don't alter the length of the aeriel once SWR'd in, it'll be fine to take off & put back (But why would you want to?)

If you feel that you must, you can even get quick release connections for them

[Guest docter fox]

i just thought that as its pretty big it would catch on the big board we have in the garage on pulleys with the model trains on.

would it be best to take it off rather than leave it bending against something on the roof?

[Jon Bradbury]

God this takes me back.

 

I used to have an ariel that mounted on any available flange with grub screws and the whip and coil assembly was easily removable via a bayonet fit to the bracket. Can't remember what make it was...

 

Can anyone tell me what it was? The coil was kind of fat (not like the dv27) and as I said was easily removable via a bayonet fit. Just turn it 90 degrees and it came off. No chance of it being nicked. I used it whilst on holiday in Torquay with my parents. I remember trying to wind some "breaker" up by telling him I was sitting in a Ferrari - what a prat!

 

<sigh> Happy days...

 

Ah, Jim, if you mount it on the back of the car you get an asymetric wave pattern don't you? You're trying to use the car as a ground plane so you'd get better performance if the other guy is in front of you. The ideal position given the car's shape would be on top of the roll bar, although that would bugger your roof a bit. A couple of those mounts would do it, one for the roll bar and one for the rear of the car as per your photo. Then, you could use the roll bar mount when the roof is down and switch the ariel to the rear when you need to put it up.

 

Um. Sorry, getting carried away. For convoy use what you already have would suffice.

[Big Jim]

I used to have an ariel that mounted on any available flange with grub screws and the whip and coil assembly was easily removable via a bayonet fit to the bracket. Can't remember what make it was...Can anyone tell me what it was?

Probably a K40, one of the best in their day (I had one too)

getting carried away. For convoy use what you already have would suffice.

you're right! as I've said, we aren't trying to contact the US of A, just Irish Bob etc.

[Jon Bradbury]

Thanks Jim, it *was* a K40.

 

Cost a small fortune second hand but I never looked back. Can't get 'em anymore can you?

[Jon Bradbury]

Here's a link:

 

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?Vie...item=5734762604

 

Mind there's no whip with it but you could acquire one from somewhere no doubt.

 

And another:

 

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?Vie...item=5734825799

 

This is one of those really small Maxcom walkie talkie style CB radios. Bit of a bargain for £35.

 

Nowt to do with me, mind, etc..

 

Cheers

 

JonB