Couple of questions re: Radarbox Extender antenna

[gleff]

Hi all,

Can anyone advise the length and mounting options of the Airnav radarbox extender?  Can I mount it easily on a horizontal pole? Is it shorter than 1.3 metres?

Also, I noticed it needs a 12VDC / 1A power supply.  Can this be run using a small Gel Cell or something?  And if so, any idea how long it will last on a charge approx.

[g0seg]

Hi Gleff, the extender antenna is 1.3 metres long but from what i remember it doesn`t need a power supply. The gain of the antenna is in the design of the antenna itself - not a preamp. Preamps are normally an addition and are for the required frequency although there are some broadband devices that can be used. I did check on e-bay here for the extender and sure enough, you can shove it on a pole without problems and the hardware for mounting appears to come with it. As for premaps, i would recommend using a mains powered voltage supply primarily because even if the device has low consumption, you`d be suprised how often a battery change is required. Hope this has been of some help, Bi now, Roger

[gleff]

Thanks Roger.

The Airnav website says the following:

     
Complete antenna system in case you already have the RadarBox and only need an antenna with pre amplifier and cables. Includes antenna, pre-amp and all required cables. You just need a 12V /1A power supply. Everything is included in the shipment:

    * RADAR-EXTENDER Antenna
    * 1m low loss cable Westflex-103
    * Mast pre-amplifier AS-1090
    * 10 or 20m low loss cable Westflex-103
    * AS-1090BT Bias-T for DC-Feed
    * 1m Cable BNC/SMA
    * All connectors included

That indicates I need a power supply and that the pre-amp is included.  Having said that, I'd love to see some specs on the antenna to see if it does indeed have a Gain on it.

As for running the power to the pre-amp.. running it from mains may pose an issue but If I can find a good external antenna with a Gain on it then I'd be happy.  I've got a pretty good one now but it's got no Gain and I'm about to lose 1.8dB from a window gap jumper.  If I can replace the external antenna with one with at least a 1.8dB Gain then it would cancel out the loss i'm about to have. (In theory anyway LOL).

Thanks for the info.  It's also good to know the airnav extender is 1.3 metres long.  That's the maximum length I can handle on my veranda.  I'd be interested to know what the Gain is on the airnav extender (without the pre-amp).  It may do the trick.

[g0seg]

Hi Gleff, ah, didn`t realise there was a complete antenna system available. All i checked was one of the advertisers on e-bay here in UK for the Radar-extender antenna - sorry about that. As for the gap jumper, i`ve been in amateur radio longer than i care to remember and the only gap jumper i`ve heard of is to protect equipment from lightening strikes!! I`ve had my box for about six months now and i tend to use the simplistic approach. I`ve replaced the curly whirly supplied antenna with an all copper version. The feeder is best quality satellite  cable - yes, i know, it isn`t 50 ohm but i`ve taken the view for many years that for receive only equipment 72-75Ohm feeder of good quality works pretty well as it`s good right upto a couple of gigs. I don`t use preamps because i`m transmitting on the amateur bands - one being 23 cems which is pretty close to the Radarbox receive frequency so i don`t want a burned out front end. I`m enclosing a recent picture - before we all went off the air because of the Icelandic ash cloud - to give you an idea of what can be accomplished. 30 feet of feeder at 40 feet high on the mast at 150 feet asl. Rule number one - antenna as high as possible in the clear and the shortest length of coax!! Sounds daft but it`s true!! (Think about it!!) have fun, Roger

[gleff]

Hi Roger,  thanks for that.

I've actually been looking around and I'm now contemplating getting the ADS-B antenna from DPD Productions.  It's got a 9dB gain so I wouldn't need a pre-amp.  It's a little longer than 1.3 metres eg.  57 inches but I could probably rig some kind of mount to allow for the extra height.

All in all it may solve my issue and at 9dB gain, it will probably be better than what I currently get even with the 1.8dB loss i'm about to get.

BTW.  The Window Gap Jumper is the CTC-50M at http://www.universal-radio.com/catalog/antsup/2750.html.  I'm going to try and use it to allow me to connect the external antenna to my indoors via a window (without drilling holes etc.).  I'm renting and leaving a window open or the veranda door open isn't an option either.

Hopefully it will work okay.

[pjm]

   * RADAR-EXTENDER Antenna
    * 1m low loss cable Westflex-103
    * Mast pre-amplifier AS-1090
    * 10 or 20m low loss cable Westflex-103
    * AS-1090BT Bias-T for DC-Feed
    * 1m Cable BNC/SMA
    * All connectors included

As for running the power to the pre-amp.. running it from mains may pose an issue but If I can find a good external antenna with a Gain on it then I'd be happy.  I've got a pretty good one now but it's got no Gain and I'm about to lose 1.8dB from a window gap jumper.

Hi Geoff

I have the RADAR-EXTENDER Antenna above with 10m of coax. Its a brilliant antenna, but the pre-amp is not required (here in Sydney anyway). With the pre-amp powered I actually receive less aircraft than with it off.  The theory is that it is overloading the RB.

Also, can you advise the mounting options.  My veranda is where I'd be putting it.  I have a horizontal railing so I'm just wondering if I'd even be able to mount it.

I'm not sure how much benefit you would receive mounting it on a verandah. Sounds like you'd have at least 180° of the view blocked, and the antenna needs clear line of sight.

fwiw here is my antenna and polar diagram, as you can see my view over most of the ACT is blocked. I'm thinking of one day putting the antenna up higher to help with the blocked spots.

[Jeremy]

What ever is blocking you to the east must be very high ground. Raising your antenna a few or 100 ft I doubt will have much affect. Such is life. Either rely on the network or move house!
Jeremy

[gleff]

I'm reasonably happy with my coverage now with the external antenna mounted on my veranda.. My issue will be when I lose 1.8dB.  My thoughts was if I can boost it by at least 1.8dB then I won't be worse off.

[pjm]

What ever is blocking you to the east must be very high ground. Raising your antenna a few or 100 ft I doubt will have much affect. Such is life. Either rely on the network or move house!
Jeremy

I'm "just" below the crest of a hill to the east, and the top of my antenna is pretty much about the same height as the houses "above" me, so I think 20 feet or so of height will give me significant gains. Likewise I'm pretty sure its just the neighbours 2 story house blocking out Canberra.

Its just a matter of me putting up a mast and a few guy wires (and getting some more low-loss coax), but not a high priority at the moment (considering I have pretty good coverage anyway and in the scheme of things the "overall" gains won't be all that much).

fwiw - my coverage of Sydney is pretty good, there is only one other RB user who gets similar coverage, so the network isn't going to help here.

[Jeremy]

At the end of the day it is good fun to try. True amateur radio spirit. Give it a go and see.  What ever you are going to receive will be line of sight so logic will dictate. If no good then hope that the network will fill in the gaps. Thats the great thing about AB and the network.
Don't forget the grey layer between network traffic and real time traffic. Some a/c might disappear.
Good luck.
73 de J.

[gleff]

Yeh.. I'll first see what the loss will be like with the Window Gap Jumper.. if it's hopeless then everything else is a moot point. 

If on the other hand it's not too bad, then i'll contemplate getting the DPD Productions antenna to see if I can compensate for the loss even if It's no better than what I currently get with the external antenna.  Basically, even if the final outcome is no better than my current external antenna coverage it will be great because at least I can use the external antenna all the time.  At the moment I can barely use it.

[gleff]

Well.. I got the Window Gap Jumper today.. I've been experimenting with it for the last few hours.  I haven't noticed any significant loss of signal.  I'm sure there is some but it's certainly not as bad as I anticipated. 

I haven't mounted it permanently yet as I'll now think seriously about getting the DPD productions ADSB antenna first.  But at least I know I've had success with the Gap Jumper.