CB Radio with external ariel in a fibreglass car/TVR

[HiAsAKite]

Folks,

Going on a charity road rally shortly.

Useful to have CB radio's to communicate between cars, looks like we're going with the externally mounted aerial type. Radios are 4W power, with 1000w aerials.

Challenge is, the aerials are magnetically mounted, and the Chimaera is a fibreglass car...

Any tips on how to fit/anyone done this before?

Considered mounting it in the central tunnel (ie coming up between the driver and passenger for roof off driving), but concerned about our proximity to the aerial itself as it will be 3-4" from us.. ....will we be at risk of RF burns?

any thoughts on mounting with marking the paintwork or car?

Edited by HiAsAKite on Wednesday 24th August 15:49

[stuttgartmetal]

Duct tap a baked bean can under the rear scuttle

[rampageturke]

Car badge adhesive? Then just heat it up with a hairdryer to remove it when done

[speedtwelve]

4W at V/UHF is nothing. You probably wouldn't want to hold on to the aerial while transmitting, but it won't fry you at 3-4".

[edc]

Not quite the same but I used a big bulldog style clip to attach to the roll bar of my Boxster. The base station was wedged between seat and sill.

[corozin]

Even if you get the ariel to stay on your signal will be rubbish as CB ariels use the metalwork of the car to create a ground plane effect and pull the signal downwards. Without that your range will be noticeably reduced.

[Havoc856]

Buy some coaxial cable from maplins. Pare back and solder the connection onto one end for the CB antenna, run the cable to the chassis, clean a part off (quick flash with the grinder) and solder it to it. Wont be getting RF burns through coated coax in the cab and you still get an ok range.

[dxg]

corozin said:

Even if you get the ariel to stay on your signal will be rubbish as CB ariels use the metalwork of the car to create a ground plane effect and pull the signal downwards. Without that your range will be noticeably reduced.

Attach a sheet of metal to the base of the aerial mag mount to act as the ground plane. Or, alternatively, some steel rods. Problem is, these "radials" should be the same length as the "aerial" which is really only half the aerial - the other half is the ground. Anyway, make sure their length is a multiple of half lengths of the CB aerial itself (i.e. a half, a quarter, an eighth...)

It can be made to work. I have seen an aerial working on the back of a bike using around a 1.5 x 1.5 square foot sheet of metal rather than radials.

[speedtwelve]

We used to stick mag-mount CB aerials onto upturned biscuit tins to make a ground-plane in the old days. Time for my medication & a nap.

[HiAsAKite]

dxg said:

Attach a sheet of metal to the base of the aerial mag mount to act as the ground plane. Or, alternatively, some steel rods. Problem is, these "radials" should be the same length as the "aerial" which is really only half the aerial - the other half is the ground. Anyway, make sure their length is a multiple of half lengths of the CB aerial itself (i.e. a half, a quarter, an eighth...)

It can be made to work. I have seen an aerial working on the back of a bike using around a 1.5 x 1.5 square foot sheet of metal rather than radials.

Thanks for the replies folks.

This where my heads at the moment, sheet of thin mild steel (or steel gauze even), cut and shaped to the parcel shelf to act as ground plane / reflector, aerial mounted magnetically to point up wards, and possibly some plastic duct pipe up overy the aerial to prevent contact RF burns in the event it flaps in the wind against something...

[HiAsAKite]

speedtwelve said:

We used to stick mag-mount CB aerials onto upturned biscuit tins to make a ground-plane in the old days. Time for my medication & a nap.

Also not so silly at all.. now how do fix the biscuit tin to the parcel shelf without drilling, sticking or glueing..

[HiAsAKite]

corozin said:

Even if you get the ariel to stay on your signal will be rubbish as CB ariels use the metalwork of the car to create a ground plane effect and pull the signal downwards. Without that your range will be noticeably reduced.

Aye.. that is the other challenge....


...on separate note, good to see you're still around and still with the rado... :-) 6 years since I sold my VR, do miss it a little.. :-(

[dxg]

HiAsAKite said:

dxg said:

Attach a sheet of metal to the base of the aerial mag mount to act as the ground plane. Or, alternatively, some steel rods. Problem is, these "radials" should be the same length as the "aerial" which is really only half the aerial - the other half is the ground. Anyway, make sure their length is a multiple of half lengths of the CB aerial itself (i.e. a half, a quarter, an eighth...)

It can be made to work. I have seen an aerial working on the back of a bike using around a 1.5 x 1.5 square foot sheet of metal rather than radials.

Thanks for the replies folks.

This where my heads at the moment, sheet of thin mild steel (or steel gauze even), cut and shaped to the parcel shelf to act as ground plane / reflector, aerial mounted magnetically to point up wards, and possibly some plastic duct pipe up overy the aerial to prevent contact RF burns in the event it flaps in the wind against something...

Sounds serious. Have you thought about the structural loads you'll be passing into the fibreglass? If you're thinking of it bending that much, think of the bending moment passing through its base. There's a reason those mag mounts are so strong...

[lostkiwi]

Fit an external speaker and Roberts your mother's brother.

http://www.ebay.co.uk/itm/Midland-Alan-42-AM-FM-Mu...