Maximum Coax Length.

[JimK]

Ok so I just took delivery of a WIMO twig. When just left dangling out of the dorma window this thing sucks up just about every thing.

So I've decided it's going on the roof of the Dorma where it will have wonderful vistas of the world. However I'm probably wanting to run this down to my shed (come shack, come Studio come everything) which is some 20 Meters from the house. Then add lets say another 20m's skyward to get to the roof.

Question am I just expecting too much and will the losses be ludicrous.

[AirNav Support]

Yes we would definitely advise a mast amp. After 10 metres of coax the loss will start to get noticeable.

[JimK]

Mast amp is on it's way from WIMO they didnt have one at the time. But being the petulant child that I am I asked for them to ship the kit now and then send on the Mast amp. Should be with me by the end of May.

So that's that bit covered.

Well I'll conduct some trials with lengths of cable and see what happens. If anyone is interested I'll post screen shots of my Polar diagram through the various experiments.

Getting up on the top of the Dorma will be no mean feat so it will be the end of May by the time I put it up there. i.e. when the mast amp comes.

Wish me luck.

[RodBearden]

Good luck Jim!

:-)

Rod
(with 15m of coax working just fine without an amp, though I know 'd pick up some more if I had one)

[steveb25]

Thanks for that guys you beat me to the punch on cable losses, my length would also be about 20m.

Jim I take it that you bought the GP-1090 Antenna?

[rocket]

Hiya,

What type coax are you lot talking about when you quote these lengths please?

[JimK]

Steve,

Yes it's the GP-1090.

Rocket,

It's Ecoflex 10 50Ohm Low loss coax. It attenuates at 1Ghz by 14.2 dB per 100meters. So I'm hoping with amplification I'm going to be ok.

Here is piccy with current rig sat on Shed roof.

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[steveb25]

Am in two minds as to what aerial to go for but the Wimo g-10190 seems to be winning.

Having said that tried something last night. In the car, polar reset, on a small hill out the back of the house, and waited.

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[JimK]

Go back there with the Wimo 1090 and you will get most of the UK covered.

I notice it's picking up all the High level stuff.

I'm trying to get down to picking up the detail at low level which is why I need to get higher. Even with the standard Aerial out of the Dorma window I can see the ground traffic at EGLL. But only on the Easterly edge.

[EINN-07]

Go back there with the Wimo 1090 and you will get most of the UK covered.

I notice it's picking up all the High level stuff.

I'm trying to get down to picking up the detail at low level which is why I need to get higher. Even with the standard Aerial out of the Dorma window I can see the ground traffic at EGLL. But only on the Easterly edge.

Another excellent source is Jim Finch in Southapton ( ssejim.co.uk ) who is incredibly knowledgeable and who has his own ADS-B antenna. I called to him a few months ago to pick up one up. I have 12m of Westflex W103 with no amp and am getting almost a 320nm diameter polar plot. The antenna is high in the clear air which is better than any amp.

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[JimK]

Just by way of a small update while I await the second part of my delivery from WIMO of the Amplifier.

Having messed around for the last half week or so swapping the WIMO twig with the AirNAV twig. I'm getting both lowish (1500) and High altitude pickups about 85NM more in certain directions with the WIMO.

These are based on being in the same location (just on top of the shed roof) Only the WIMO has 20M of Coax. It's interesting and clearly means the WIMO just standalone wins hands down. But the it has to be said the AirNAV twig clearly is an ok bit of kit!!!

As soon as I get the Mast Amp from WIMO (end of May alas :-)) I'll post some more results. Cable length tests are going to be the real key here. What I can't do is make repeated trips to the Roof so I'll post some tests all in the space of say 48 hours, while I have the Long Reach ladders, as and when I get the Mast head Amp.

Jim

[JimK]

Ok the Amplifier arrived from WIMO exaclty on the date they said it would. Top service.

Anyway that aside I'm going for plan B. Getting the Twig on the Dorma roof and then running a a cable all the way back was just going to be too much of a challange. So I managed to buy from Radioworld a telescopic mast. It runs to 19m high and can be installed along side the shed. More to the point it's portable which means I can take it down etc.

It all arrived today. Although its not stopped raining down sarf so it may be a while before I get it all built. I'll keep you informed.

JimK