Thread: What happened to your Discovery 2 today?

Originally Posted by RRT

Sure is funny how much time you can spend looking for parts.. Have the 2db and 6db aerials mounted on the bullbar and they come to a spiltter / switching box and then, this required a cable from this to the uhf aerial input. After much searching and today going around 4wd and auto stores trying to find such a thing. Didn't care if it was 200 metres or 0.5 just want to connect the splitter to the uhf.


Finally thanks to Jaycar staff, rather than making up a cable they finally came around to making this and problem solved. Was planning on putting the spiltter in the glove box and the uhf box where I have removed the cup holders in the dash, but nah, they can go together now in the glove box.

Attachment 176160

$15 and done, love it when a plan comes together - and got to get a brand new jaycar catalogue!

That “connection” combined with the splitter will be costing a heap of db gain. (Actually giving losses)

You’d be better off with just one of the antennas.

Originally Posted by Tombie

That “connection” combined with the splitter will be costing a heap of db gain. (Actually giving losses)

You’d be better off with just one of the antennas.

Hmmm, did not know that and still don't know it now after having a quick search on such things lol.

As far as practical without taking out a summer diploma on it, what sort of % of performance do you think it would suffer.

Went the two aerial system after being 'lost' in the VHC, in the dark and at the time inexperienced in driving 4wd, long story short at best intermittent staccato communication due to only having a 6db aerial to others with 6db aerials. 3.5 hours till got out to made roads and even then was really only about 400-500 metres from their camp that we could communicate properly.

That said can ditch it and just swap the aerials which isn't as 'neat' but performance is important.

Yeah, I wouldn't have done the splitter either.
If you think about it, you're either in 2db country, or 6db country .. not usually both at the same time.

That is, it takes a few hours to go from one terrain type to another .. so not a hard task to just have the two interchangeable aerials, pull up, have a smoko, kick tyres, change aerial types for the terrain ... pack aerial away ... continue on.

Originally Posted by RRT

Hmmm, did not know that and still don't know it now after having a quick search on such things lol.

As far as practical without taking out a summer diploma on it, what sort of % of performance do you think it would suffer.

Went the two aerial system after being 'lost' in the VHC, in the dark and at the time inexperienced in driving 4wd, long story short at best intermittent staccato communication due to only having a 6db aerial to others with 6db aerials. 3.5 hours till got out to made roads and even then was really only about 400-500 metres from their camp that we could communicate properly.

That said can ditch it and just swap the aerials which isn't as 'neat' but performance is important.

It’s called “insertion loss” so the less number of connectors the better. Also rather than stacking the connectors as you have, making a patch cable would be preferable, both RF wise and mechanically, and $ wise too. Gaining access to a SWR Bridge or Meter (SWR = Standing Wave Ratio) will show you the efficiency of your installation relating to antenna tune and transmitted watts. A de-tuned installation for whatever reason will result in RF (watts) being “reflected” back down the coax to the transmitter which means less transmit power at the antenna. A commercial radio installer can help you with this.
PS: a tuned installation with a high mount 1/4 wave antenna punching out a full 5W would be the most suitable antenna for the High County.

Originally Posted by onebob

It’s called “insertion loss” so the less number of connectors the better. Also rather than stacking the connectors as you have, making a patch cable would be preferable, both RF wise and mechanically, and $ wise too. Gaining access to a SWR Bridge or Meter (SWR = Standing Wave Ratio) will show you the efficiency of your installation relating to antenna tune and transmitted watts. A de-tuned installation for whatever reason will result in RF (watts) being “reflected” back down the coax to the transmitter which means less transmit power at the antenna. A commercial radio installer can help you with this.
PS: a tuned installation with a high mount 1/4 wave antenna punching out a full 5W would be the most suitable antenna for the High County.

Looked up the 1/4wave and that is one of the ones that I have, glad! Location, hmmm, sitting atop the bull bar...

Thinking it may just be better to leave the two aerial cables loose and hook up when needed, i.e. hit the VHC and the 2db goes in and only a single connection. Without taking the splitter apart I am probably pretty certain it is not beautiful in there.

How would this be tuned per se if the cable simply ran from the antenna to the receiver, other than positioning of the aerial of course. The aerials as per the pic are off the body / bonnet by about 10cm or so, well grounded with the bullbar etc. The roof is already covered with the RTT and this would afford some protection as to damage, but at what price to reception???


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It would be folly to discount a huge percentage by placement of the aerial, but as always there are degrees that one can deem acceptable I suppose.

BTW on the bullbar most of your signal is going backwards as the ground plane of the bonnet and turret is the main ground plane.

If I were to put Antennas on my bullbar I would fit ground plane independent antennas , so that the signal would radiate more equally.

My setup is a small 4DB ground plane independent fibreglass whip above my drivers door B pillar and that will give a more even radiation pattern and is higher up. It is fitted to a pivoting mount so that it doesn't get hit by the garage door

I have a BIG 8 db helical whip just lying in the back of the car if I am ever out in the desert wanting to communicate . Both whips will just screw into the ground plane and are interchangeable.

I hardly ever have it on now I am not in convoys anymore as I cannot stand the inane and obscene chatter.

Regards PhilipA

Hi RRT,
Re: “How would this be tuned per se if the cable simply ran from the antenna to the receiver, other than positioning of the aerial of course”
A common 1/4wave antenna for UHFCB is actually “broad band” and covers from 380 to 520Mhz. They are OKAY in a straight forward installation like a simple cable run between transceiver and antenna. However the 80 UHFCB band is comparatively narrow with the channels ranging from 476.4250 to 477.4125 but the 1/4 wave broad band antenna is able to be tuned to the centre of the band ie ch40 to squeeze the max efficiency out of the meagre 5W we are allowed to transmit. The antenna is tuned by adjusting the length of the radiator, usually by shortening it whilst observing the SWR. Many owners don’t bother with it - some of us do though .
PS: is it an Antenna OR an Aerial? ……. Accepted usage is that an Antenna is used for Transmitting and Receiving and an Aerial is for reception only.

Interesting seeing a SWR meter used for the UHF.
I've often wondered if it should be done but I've never seen or heard of anyone testing and trimming.
And I've never asked anyone that would know.
Thanks for filling in the knowledge gap.

Back in the old days of 27MHz it was considered mandatory on a new installation (god I feel old saying that )