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Author Topic: Using a VHF antenna for RB  (Read 6731 times)

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bailey_uk

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Using a VHF antenna for RB
« on: September 10, 2010, 08:27:52 PM »
The small BNC Connector on the end of the shipped Antenna is on its last legs and finally dropped off today, so  thought i'd try using a magmount VHF antenna that I bought for my scanner in the car. Very impressed with the results, still picking up aircraft a long way away, even with it just sat on my velux window of my bedroom, so will be using this instead of reparing the shipped one for the time being.

However, this got me thinking - I connected the RB to my SSJ VHF antenna setup, installed high on my chimney with no obstructions, using RG213u (about 13m) and thought id be onto a winner........very dissapointed! Hardly any hits and those aircraft I do receive have to be very close to be shown on the map :-(
I cant afford an external 1090mhz antenna at present but honestly thought that the VHF one would of performed better than this considering the VHF magmount works splendidly.

James


Possibly the youngest RadarBox Owner!

zina

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Re: Using a VHF antenna for RB
« Reply #1 on: December 09, 2010, 12:54:49 PM »
Any toughts about a loss on RG... same problem here with Discone, but 60 mtrs of cable... a tough one

Runway 31

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Re: Using a VHF antenna for RB
« Reply #2 on: December 09, 2010, 01:27:09 PM »
I am no expert but I think they work at different frequencies with the RB needing one designed for 1090Mhz as opposed to the VHF frequencies.

A replacement for your original isnt that expensive and is easily obtained.

Alan

zina

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Re: Using a VHF antenna for RB
« Reply #3 on: December 09, 2010, 01:44:35 PM »
Alan,
Exactly! 1.1 Ghz is a tricky one! You either have an designed antenna for this frequency, or... Hence a nice reply from any "scanner" antenna covering anything till 2,4 Ghz, but we still need a clear horizon to catch as much planes as possible. So, couch antenna or car roof antenna will work superbly as long as its horizon limitations allows. Therefore, for home use logical solution is to have an aerial on a top of house, tree etc, higher he point the better it is. If this is a case, we will need some "serious" length on this frequency and as a result we will have a different response from feeding line (cable) hence some premplifier is needed due to a loss on a line, or some really high quality cable - I had some mind puzzling different results from MIL SPEC and Commercial cables.

Bregards
Milan
« Last Edit: December 09, 2010, 01:46:51 PM by zina »

bratters

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Re: Using a VHF antenna for RB
« Reply #4 on: December 09, 2010, 04:44:54 PM »
Referring to the original question the only aerial that will work well with RB is a dedicated 1090 aerial. The supplied aerial itself is very good though not for outdoors.

The secret of a successful roof aerial is a short aerial cable and a long USB.
The best way to achieve this is to run the aerial cable into the box at the earliest opportunity which usually means siting the box in the loft. Then run an extended powered USB cable from the box down to where your PC/laptop is sited.

Golden rule - there is no signal loss with USB cable but there is with aerial cable. So short aerial/long USB.

Search through the forum - there's chapter and verse out there already. 

zina

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Re: Using a VHF antenna for RB
« Reply #5 on: December 09, 2010, 04:59:17 PM »
Mirabile dictu! Generalis!

As for previous... some 60 Mtrs. above my QTH is an wonderland location, covering at least 7 airports... This QTH is checked & rechecked with portable PC and  all antenna combo. I already have mine antenna farm above and can provide all live ATC/plane-plane feed, but... 1,1 Ghz just need an preamplifier, owise - signal is lost on a drain!
Having one (Pre Amp) on a table, will keep You posted when the simple box is up and running! Will not accept my lovely RB as an "underachiever!"

73

Milan

zina

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Re: Using a VHF antenna for RB
« Reply #6 on: December 09, 2010, 05:04:49 PM »
BTW...

Recollecting some prehistorical lessons... max USB cable 15ft??????

I am still impressed with a quality of signal by a provided antenna! This is an 5/5 product! Even a radial ground in a size of CD is a superb solution. Just happy to have one!

But sure to adjust it to mine needs/prospects!

Keeping You posted,

Milan


bratters

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Re: Using a VHF antenna for RB
« Reply #7 on: December 09, 2010, 05:38:54 PM »
BTW...

Recollecting some prehistorical lessons... max USB cable 15ft??????


No, you can do better than that. Have a search on ebay for 10mtr even 15mtr (I think) powered USB extenders.  Won't break the bank either.

CoastGuardJon

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Re: Using a VHF antenna for RB
« Reply #8 on: December 09, 2010, 06:43:33 PM »
I agre with Bratters' comment re powered USB extender - I've got 12m Lindy with its own PSU after trying high quality but non-active extenders, which killed everything - totally useless!    I thoroughly recommend this one

http://www.lindy.co.uk/12m-usb-2-active-extension-pro-4-port-hub/42783.html

Not the cheapest, but you get what you pay for.
ANRB :  AOR AR8000 : Icom R-7000 : Icom IC-R9000 : JRC NRD-545 : OptoElectronics Digital Scout and OptoLinx Interface; Realistic Pro-2005 : UBC 800XLT - listed in alphabetical order, not cost, preference, performance or entertainment value!

glennradio

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Re: Using a VHF antenna for RB
« Reply #9 on: December 10, 2010, 10:38:01 AM »
I have been spending some time experimenting with various runs of cable for the RB I use in my basement.  I have placed the supplied antenna outside and up about 20 feet and connected the SMA connector to an F adaptor and use 75 ohm satellite cable rated for up to 2500 MHZ to deliver the signal.  I am happy with the result and getting much better reception now, than when using UltraFlex 400, RG8, RG213 or other 50 ohm transceive cable as the losses at 1090 MHZ are too high.  I also use a 24 db amplifier as the cable run is around 50 to 60 feet.  I have a Discone and believe it or not, an HD 4 Bay TV antenna for directional purposes.  These are fed into a 2500 MHZ combiner for the Satellite cable and considering my location is surrounded by high hills (which limit the signal reception) my use of the satellite cable has been a success and inexpensive. Experiment, however because of the frequency, it is a major factor to keep in mind.  Hope this post helps.
Cheers!

AirNav Support

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Re: Using a VHF antenna for RB
« Reply #10 on: December 10, 2010, 11:07:03 AM »
Please do not use the supplied antenna which comes with RadarBox outside for long periods of time. It is not designed to survive the weather and you may find damage to your RadarBox if you use it externaly mounted.

Please read

http://www.airnavsystems.com/forum/index.php?topic=2759.0

Contact Customer/Technical support via:
http://www.airnavsystems.com/contact.html
[email protected]

glennradio

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Re: Using a VHF antenna for RB
« Reply #11 on: December 12, 2010, 02:41:48 AM »
Thanks for the information.  Was using the stock antenna to provide a "footprint" for comparison purposes with my experimenting.  I was pleasantly surprised with the result.

glennradio

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Re: Using a VHF antenna for RB
« Reply #12 on: December 12, 2010, 03:30:36 AM »
Update:  I have modified a Midland 18-4003 antenna and use 3.5 gigahertz rated satellite cable to feed my RB about 15 to 20 meters distant.  There is a connect point in the feed line with a coupler that I use for grounding at a ground rod.  The "footprint" from this antenna is very similar if not just slightly better than the supplied antenna for the RB.  I would be interested to trial this antenna at a location that is more open to reception however am very pleased with my project.  I too had difficulty with the signal feed due to the losses of my cable but was determined to be in a position where I could monitor the RB and computer at the same time.  That has been accomplished.  Must have been the sub zero temperatures that spurred me on to completion.

bratters

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Re: Using a VHF antenna for RB
« Reply #13 on: December 12, 2010, 07:53:28 AM »

I too had difficulty with the signal feed due to the losses of my cable but was determined to be in a position where I could monitor the RB and computer at the same time. 

It took me a long time to get to grips with the fact that the RB does not need monitoring. It's something psychological I suppose but the box either works or it doesn't and looking at flashing lights will neither help nor hinder.

I haven't seen my RB for over 8 months now. It is loosely wrapped up in a dust protecting bag happily blinking away in a dark corner of my loft - denying me the temptation to tinker with things that are best left alone!

Good luck with your experiments - when you get it right and the range and numbers shoot up, it is a very satisfying moment. It is also the moment to stop playing about :)

glennradio

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Re: Using a VHF antenna for RB
« Reply #14 on: December 13, 2010, 04:57:14 AM »
Bratters, I don't think your situation with RB is the same as mine.  I like to have my RB handy and not parked in my attic so if necessary, when lightening storms approach, it can be disconnected quickly.  I prefer outside antennas so my equipment can provide maximum performance where possible.  My challenge was to get outside and high to provide the best reception for a location that resides at the bottom a 270 degree bowl shaped area.  I have high ground all around including the Niagara Escarpment only 5 minutes away which tends to block out reception to the north, west and southwest. :(
My suggestions are for the consumption of those who may want something better, than locating the RB in a dust protecting bag, and knowing there are other solutions available to them.  I appreciate the suggestion of a powered usb extender, however it does not work for me in my situation.  Playing about is what makes the hobby fun and being able to duplicate or better the performance of the stock antenna with a 15 to 20 mtr run of cable is a good start, just keep things safe. 
I think the discussion in this forum is presenting some good thoughts and all should be considered and used as individuals see fit.  I am glad, for sure, that you were able to locate the RB in place where you wouldn't be able to bend to your temptation and tinker with it, that unit is best left as is. :)
Can you provide any info about your station setup?  Are you near an airport, is the area around your place hilly or flat?  Is your antenna stock and do you also keep it located in the loft? :)  My improvement so far is an average of 40 nm better in 3 directions over the stock setup at 6 1/2 mtrs height. :)