RogerStenning said:
The actual antenna for the AM/FM receiver in mine is apparently the boot door (not IN the boot door, but IS the boot door), would you believe?
Click to expand...

I'd be very surprised at that, unless somebody in the past has been chopping things about.
If you take a look at the rear side windows, there should be three metal lines etched down the middle of each. That being the case, the FM aerial is built into the nearside window and the AM aerial is built into the offside window. Each window has a small amplifier above it. The feeders to the head unit are the normal sized one is the FM and the thinner one is the AM aerial.
This assumes that the head unit is the Alpine R990 unit or better.
 
gstuart said:
sounds like a good idea ref the trunking

found out my am/fm radio aerial is incorporated in the side window

will have a look at that aerial to see if it's suitable for mine as well

the hole is near the back of my roof , so wonder if i could then simply fold it down when not needed

what length aerial are u going to use

wonder if the cb would work with the cb aerial pointing forwards and nearly laying down

so when off road it doesn't catch on any branches etc
Click to expand...

The antenna length in total, less mount, is approximately 1.257m. This based on the 49.25" in the specs (see http://www.diamondantenna.net/pdfdocs/CR8900.pdf) The foldover is at about 12cm, less mount height. You could fold it down when not in use, but you'd have to remember about the lower coil height. When mine will be folded down, none of the antenna will show above the line of the roof, which is why I mounted it on the rear door. I'l post photos when the job's completed tomorrow.

I couldn't say about a CB antenna, but if it's one of those open coil base-loaded ones that off-roaders seem to favour, unless the mounting is especially fragile, I shouldn't worry too much about tree strikes overly much.

Regarding operations when folded over, I wouldn't; while there is a form of transceiver antenna that is designed to transmit folded over by design (iirc, a blade antenna), a conventional antenna is not designed to so so; for a start, I would imagine the VSWR would be radically changed due to the radiating element being so close and parallel to the ground plane; the radiation pattern would be radically altered (I'd guess that the smith chart would be amazing, though!), and you could cause problems resulting from the foregoing to the P.A. of the transmitter, possibly irretrievably (think Blown P.A. stage).

re the AM/FM antrenna - yep, I was told wrong, it's in the side window (just looked at the RAVE manual for the Disco 2 td5) :D
 
gstuart said:
just found this

gives a 1-3 mile radius and wondering this could be an ideal solution

thoughts please

http://www.4x4cb.com/public/item.cfm?itemID=712
Click to expand...

neilly said:
What are you planning on connecting it you Gary?

If you are fitting a cb, then remember you will need to check the SWR. Fro yours I would have thought a mag mount would be better.

Cheers
Click to expand...

Neilly, you beat me to it :D

Gary, the VSWR adjustment will likely be something of a bitch. See if you can find a manual for it before purchase, to see how much trouble that might be for you. Other than that, yeah, it's a nice low-profile idea, but it does sacrifice range as opposed to a more conventional transceiver antenna.
 
Unless you're prepared to pop a 3/8" or 1/2 or sometimes even bigger hole in the roof, you're probably going to have to accept the aerial cable coming out of the vehicle through a door seal. The only alternative I've heard of is a capacitively coupled method where the signals can be made to couple through the glass of a window, but I've only ever seen that for mobile phones.
The use of a CB set is often, but not always limited to "green-laning days", so by its nature the installation could be considered as a temporary fit or even a handheld, and that philosophy sometimes applies to the aerial too; that then puts the user into the realms of gutter clips or magnetic mounts. The material from which the vehicle was built now becomes a major consideration, I've yet to see a magnet that will stick unaided to an aluminium or GRP body panel.
If the vehicle is steel, then a magnetic mount will work fairly well, but obviously not quite as well as a larger permanently mounted aerial in terms of range and coverage, but in terms of tuning, the capacitive coupling rather than a hard wired connection to the groundplane is taken into account during the initial design.
Magnetic mount aerials tend to be shorter than the permanent types and therefore more suited to temporary installations, largely because of the possibility of the aerial becoming detatched whilst the vehicle is in motion which is more of a hazard with a longer aerial.
Those who wish to permanently install communications kit will probably be more likely to consider a hole in a body panel as just "a price that has to be paid". Obviously if an existing hole can be adapted or otherwise pressed into service then so much the better.
Personally, I'll accept the limitations of "mag-mounts" over drilling another leak in the vehicle. I have two mag-mounts in my collection, one a short CB aerial and the other for PMR446 kit (which might be a little bit unlawful, but ...).

Dual band mag mount for the UV5-R: http://www.ebay.co.uk/itm/NAGOYA-UT102-Car-Mobile-Antenna-for-BAOFENG-UV5R-Plus-UV5RA-Plus-UV3R-Plus-UK-/221476158078?hash=item339101fa7e:g:R-IAAOSw-nZTqnB6

27 Mhz CB mag mount: http://www.ebay.co.uk/itm/CHEAP-Mini-Mag-Mount-CB-MOBILE-ANTENNA-Canva-874-TTi-President-Midlands-/172279875461?hash=item281cae4785:g:SEMAAOxyl5lSKeQB

I'm all for using as cheap as possible on the outside of a vehicle, because on the outside, things tend to be more vulnerable to damage and loss and if cheap does the job, why go expensive?
 
There are a few schools of thought on antenna mounting on cars; one option used by several organisations, mostly, it has to be said, in the USA, is the NMO (New MOtorola) mounting system.

Yes, it tends to require a new hole be drilled into the car body.

But that's where it tends to stop, as the seal tends to be more waterproof than other mountings, and it uses a somewhat different thread than the SO239/PL259 (which itself is not exactly a waterproof itself) system to screw antennas into it.

The problem is that there are no dedicated Amateur or (as far as I know) CB antennas made for this mounting system, it being primarily a "professional" system (note the pompous quote marks there) so we're right back to mag mounts, gutter mounts, corner mounts, boot lip mounts, and similar.

Some get around the 'leaky exit' issue like I did, and drill a hole somewhere not immediately prone to leakage issues, and seal it as best they can.

Some try the capacitative 'through the glass' method which is lossy as ****, by the way, and results in lower received levels of signal to your receiver, and a higher chance of VSWR-related transmitter issues (it's a complex subject even without the maths, and I'm not going to inflict that crap on you all!).

Still fewer draw out the antenna cable through an existing hole (there aren't too many of those in modern cars, aside from the doors, boot, and bonnet), generally through the bulkhead between the cabin and the engine, and route the cable under the vehicle to a point where it can be brought 'up and over' to the antenna, which requires a LONG cable, it has to be said.

And finally, the majority of people trust to luck, the tooth fairy, et al, and take the cable through a door/boot/bonnet and hope the door seal doesn't get too messed up along the way.

At the end of the day, choosing your preferred way of getting the signal to the antenna is down to you, your faith in WD-40, a mop, sponge, bucket, and luck.

Normally, I'd go with an easy solution, as they tend to be easier to fix if (when) they go wrong. That said, I went with the drilled hole approach this time - your mileage might vary!

Have fun! ;)
 
Last edited:
if you want to use the CB for laning, you only need a mile at most range.
i know peeps that mount the aerial on the front or rear bumper and find it more than adequate. A mag mount gets knocked off all too frequently.The other option is to use a spare wheel carrier mounted aerial mount and run the cable through the rear door and out thru a grommet beneath the spare wheel mount,
 
Last edited:
The Mad Hat Man said:
if you want to use the CB for laning, you only need a mile at most range.
i know peeps that mount the aerial on the front or rear bumper and find it more than adequate. A mag mount gets knocked off all too frequently.The other option is to use a spare wheel carrier mounted aerial mount and run the cable through the rear door and out thru a gromet beneath the spare wheel mount,
Click to expand...

Similar to what I've done (last option you noted)
 
brian47 said:
Unless you're prepared to pop a 3/8" or 1/2 or sometimes even bigger hole in the roof, you're probably going to have to accept the aerial cable coming out of the vehicle through a door seal. The only alternative I've heard of is a capacitively coupled method where the signals can be made to couple through the glass of a window, but I've only ever seen that for mobile phones.
The use of a CB set is often, but not always limited to "green-laning days", so by its nature the installation could be considered as a temporary fit or even a handheld, and that philosophy sometimes applies to the aerial too; that then puts the user into the realms of gutter clips or magnetic mounts. The material from which the vehicle was built now becomes a major consideration, I've yet to see a magnet that will stick unaided to an aluminium or GRP body panel.
If the vehicle is steel, then a magnetic mount will work fairly well, but obviously not quite as well as a larger permanently mounted aerial in terms of range and coverage, but in terms of tuning, the capacitive coupling rather than a hard wired connection to the groundplane is taken into account during the initial design.
Magnetic mount aerials tend to be shorter than the permanent types and therefore more suited to temporary installations, largely because of the possibility of the aerial becoming detatched whilst the vehicle is in motion which is more of a hazard with a longer aerial.
Those who wish to permanently install communications kit will probably be more likely to consider a hole in a body panel as just "a price that has to be paid". Obviously if an existing hole can be adapted or otherwise pressed into service then so much the better.
Personally, I'll accept the limitations of "mag-mounts" over drilling another leak in the vehicle. I have two mag-mounts in my collection, one a short CB aerial and the other for PMR446 kit (which might be a little bit unlawful, but ...).

Dual band mag mount for the UV5-R: http://www.ebay.co.uk/itm/NAGOYA-UT102-Car-Mobile-Antenna-for-BAOFENG-UV5R-Plus-UV5RA-Plus-UV3R-Plus-UK-/221476158078?hash=item339101fa7e:g:R-IAAOSw-nZTqnB6

27 Mhz CB mag mount: http://www.ebay.co.uk/itm/CHEAP-Mini-Mag-Mount-CB-MOBILE-ANTENNA-Canva-874-TTi-President-Midlands-/172279875461?hash=item281cae4785:g:SEMAAOxyl5lSKeQB

I'm all for using as cheap as possible on the outside of a vehicle, because on the outside, things tend to be more vulnerable to damage and loss and if cheap does the job, why go expensive?
Click to expand...

thks, will have a read through the links

there is already a hole in the roof at the back , where a gps should go, have a blanking grommet which i think is at least 1/2 inch

headlining has to come out so will then be an ideal time to measure it and then can decide on the options i then have

thks again
 
neilly said:
What are you planning on connecting it you Gary?

If you are fitting a cb, then remember you will need to check the SWR. Fro yours I would have thought a mag mount would be better.

Cheers
Click to expand...

thks, yes a cb, tti900 , got a small swr meter

only have to get an aerial and lead for it
 
RogerStenning said:
The antenna length in total, less mount, is approximately 1.257m. This based on the 49.25" in the specs (see http://www.diamondantenna.net/pdfdocs/CR8900.pdf) The foldover is at about 12cm, less mount height. You could fold it down when not in use, but you'd have to remember about the lower coil height. When mine will be folded down, none of the antenna will show above the line of the roof, which is why I mounted it on the rear door. I'l post photos when the job's completed tomorrow.

I couldn't say about a CB antenna, but if it's one of those open coil base-loaded ones that off-roaders seem to favour, unless the mounting is especially fragile, I shouldn't worry too much about tree strikes overly much.

Regarding operations when folded over, I wouldn't; while there is a form of transceiver antenna that is designed to transmit folded over by design (iirc, a blade antenna), a conventional antenna is not designed to so so; for a start, I would imagine the VSWR would be radically changed due to the radiating element being so close and parallel to the ground plane; the radiation pattern would be radically altered (I'd guess that the smith chart would be amazing, though!), and you could cause problems resulting from the foregoing to the P.A. of the transmitter, possibly irretrievably (think Blown P.A. stage).

re the AM/FM antrenna - yep, I was told wrong, it's in the side window (just looked at the RAVE manual for the Disco 2 td5) :D
Click to expand...

thks for the heads up and some great advise
 
thks so much guys

i've been offered some short roof rails , where i assume i can get a gutter mount for it

think once i get the headlining out i can then accurately measure the existing hole in the roof at the back

that will then determine in what i can do,

A / if the hole is big enough to accept a suitable mount

B/ if not to look at a magmount

C/ getting some second hand roof rails

cb is a TTi 900

so it will just be the case of buying an aerial according to its fixing position and lead

found a good place to fix the cb in the glove box, as i don't want it fixed on the dashboard or to see wires anywhere

thks so much once again and got some reading to do through the links you've kindly provided
 
found some pics of aerials fitted to a D3

the rails shown are the ones i'm getting second hand for £20

they just need a clean and a spray , thought it being ideal getting them second hand as new ones are silly money

what are ur opinions please on the mount and aerial, haven't got a clue what type it is

this is one option

IMG_0944.JPG
IMG_0945.JPG
IMG_0946.JPG
 
gstuart said:
this is another type
(snip)
Click to expand...

Oh, now those are rather neat :) I like the first mount; it's easy for you to nip out and fold it over without requiring tools (assuming the wingnut isn't done up too tight, of course!) - the second would require a couple of spanners on hand.
 
RogerStenning said:
Oh, now those are rather neat :) I like the first mount; it's easy for you to nip out and fold it over without requiring tools (assuming the wingnut isn't done up too tight, of course!) - the second would require a couple of spanners on hand.
Click to expand...

have found out the guy who makes them and emailed him

would be good with the wing nut system as they do indeed just fold flat to the roof

would just have to leave enough slack on the cable

also wondering if i could take a cable through the top of the rear light, as there's a vent hold behind it

of even feeding it through the hole in the roof, making up some form of decent clamp grommet system
 
gstuart said:
have found out the guy who makes them and emailed him

would be good with the wing nut system as they do indeed just fold flat to the roof

would just have to leave enough slack on the cable

also wondering if i could take a cable through the top of the rear light, as there's a vent hold behind it

of even feeding it through the hole in the roof, making up some form of decent clamp grommet system
Click to expand...

On the wingnut mount - there are a lot of those about; I was referring to the way it mounts into the roof rack track, sorry, I should have been a bit clearer :)

WRT the cable ingress, yeah. Not an easy choice. The clean way, not leaving any trace on the vehicle for later resale, would be to run it in the way the guy in the photo did, via the boot, over the seal rubber. There are many, many people who do it that way, and for the most part, it doesn't cause any real problems, you just need to check the cable every so often to ensure it hasn't become pinched, and the seal, to ensure it's still reasonably effective.

Granted, I drilled a hole in mine, but mine's darn near 17 years old, and yours is a lot younger and better looking ;)
 
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