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Author Topic: Not receiving many flights  (Read 23566 times)

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bernesemad

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Re: Not receiving many flights
« Reply #15 on: October 08, 2008, 08:07:35 PM »
mine too !!!

Terry

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Re: Not receiving many flights
« Reply #16 on: October 08, 2008, 08:41:38 PM »
Don`t be nervous about using the Elad pre-amp Oceans777,i`m running one with a BS-1100 with the high gain whip,I had problems with the pre-amp to start with as i put it about 18" below the antenna and it started to intermittently tick quite loud and the number of local aircraft dropped off.After talking to a radio ham friend he told me to put the pre amp as it states at the mast head,or as close as possible,for some reason if its too low it cannot deliver enough D.C current.I then put the pre-amp up to the ground planes of the antenna and ding, ding away it went.Ive had no problems YET, but i am in a superb position at this location and my highest number on "My Flights" has been 600+ to date,and my polar diagram is good,my furthest spike reaching 270nm. 


           Hope this eases your concerns,
                                                         Regards Terry.
 

   P.S A good friend of mine,Glyn is about to get the Kuhn pre-amp,He also has a location like mine,so no doubt we will compare pre-amps etc,when he gets his up and running.
« Last Edit: October 08, 2008, 08:48:20 PM by Terry »

AirNav Support

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Re: Not receiving many flights
« Reply #17 on: October 08, 2008, 09:26:47 PM »
You have no issue to worry if you are using a preamp. As Terry says any ESD won't make it back to the RadarBox.

In most cases we have found boxes are either severely damaged due to a lightning strike nearby or customers have used antennas kits with no ESD protection and in high ESD areas.
Contact Customer/Technical support via:
http://www.airnavsystems.com/contact.html
[email protected]

oceans777

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Re: Not receiving many flights
« Reply #18 on: October 08, 2008, 09:45:43 PM »
thanks Terry and support - mine arrives tomorrow so that's very useful info.
I did not know about the positioning of the amp being so important. Thanks!

Terry

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Re: Not receiving many flights
« Reply #19 on: October 08, 2008, 09:56:13 PM »
No problem Oceans777,
                                   This is what sets this forum apart from others i will not mention,HELP and SUPPORT from all RB users and of course the AirNav team.What is a hobby if we cannot help each other,"A WASTE OF TIME AND MONEY",plus we all promote the hobby by using the Forum as a market place of knowledge and experience,better shut up or no doubt my mate Glyn will be giving me an ear bashing on how to stop waffeling on he!he!.

                                       Regards Terry.

flightchecker

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Re: Not receiving many flights
« Reply #20 on: October 09, 2008, 10:02:14 AM »
Good morning Terry,
what do you mean by this:

Quote
for some reason if its too low it cannot deliver enough D.C current

could you explain a bit more in detail?
 
A preamp does not "deliver" current", it "draws" current if connected to a power supply
(via Bias Tee [and the inner coax conductor] or individual supply leads)

Kind regards


Karl

Terry

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Re: Not receiving many flights
« Reply #21 on: October 09, 2008, 10:48:32 AM »
Certainly,
                When i originally set up the pre-amp i put it about 18" below the antenna,when i got it all up and running i noticed a drop in local traffic,my wife called and told me there was a noise coming from my antenna.I got the ladders out and up i went,to be greeted at the top by an intermittent loud clicking noise,so down came the whole thing and after testing the D.C current(11.9v) and making sure that  nothing was or had been damaged,i rang a radio ham friend and told him about it,he told me that some pre-amps don`t deliver(or draw as you rightly say) full power if they are not at mast head(it seems a bit strange i know,but this guy wouldn`t fob you off),so on a trip to a well known amateur radio shop i took it with me and had it tested,all was fine and the engineer who tested it said exactly the same as my friend,get it as close to the antenna as possible,this i have done and i`ve had no problems since?Maybe you have knowledge on this matter and may shed light on this phenomena if thats what it is.

                                      Regards Terry.
« Last Edit: October 09, 2008, 10:59:35 AM by Terry »

oceans777

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Re: Not receiving many flights
« Reply #22 on: October 09, 2008, 12:27:42 PM »
Did this also mean you shortened the coax cable from the pre-amp to the antenna Terry? I have about a two foot (.6 meters) length of LMR-400 (about the same as EcoFlex but solid core instead of stranded) that I plan to use. The coax from the power side of the amp back inside to the bias t is about 60'.

I can't figure out what electrical 'rule' is preventing the pre-amp from having enough current unless mounted right at masthead. I know they are best mounted as close to the antenna as possible for optimum signal amplification.

I've  been using a Dressler ARA2000HDX with a self-contained amp, the PSU shows an output of 12.5 volts which turns into 11.8 volts at the N-connector to the antenna. Then again it has 1000mA where as I think the Elad only outputs 100? Maybe thats the difference. The Dressler only uses what it 'needs' of the 1000mA according to the tech sheet and normally operates within 100 - 200 mA.

Although that has always baffled me too. How can the amp decide it suddenly needs 1000 mA?
I am definitely going to do some reading on diplexers etc today just to answer my own questions.

Sorry for the long ramble, but it's all very interesting to me.
« Last Edit: October 09, 2008, 12:31:06 PM by oceans777 »

Terry

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Re: Not receiving many flights
« Reply #23 on: October 09, 2008, 12:44:53 PM »
Hi there Oceans777,
                              No,i didn`t shorten the feed from the pre-amp to the antenna,but i did secure it half way with a cable tie and taped it.I`m just as baffled as you or maybe my mate meant DC supply,but even then the engineer that checked it out said the same thing,maybe Karl knows the answer?,all i know is that when i did as my mate sugested it works fine and no problems.Don`t  worry about the ramble,obviously there are conflicting views and they need to be answered,but as stated with my own experience i have no problems with the pre-amp now.

                            Regards Terry.

oceans777

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Re: Not receiving many flights
« Reply #24 on: October 09, 2008, 12:49:51 PM »
Hi Terry,

Thanks for that info. I'll place mine the same at the very top under the ground radials. I guess if it's working that's what we care about. Thanks again!

Terry

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Re: Not receiving many flights
« Reply #25 on: October 09, 2008, 01:38:08 PM »
I hope you get the same results from your Elad as i have,i know they are a little expensive,but like they say,you only get what you pay for and i`m pretty sure you won`t be dissapointed.

                                Regards Terry,
.
  P.S. I have 1Metre of feed from the pre-amp to the antenna and 10 meters of thin coax down to the bias tee!
« Last Edit: October 09, 2008, 01:52:45 PM by Terry »

oceans777

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Re: Not receiving many flights
« Reply #26 on: October 09, 2008, 01:49:03 PM »
Has to be better than just attaching the RB antenna to 60' of coax on the roof. My biggest problem are mountains to my north and east. Hoping the amp will let me see aircraft at lower altitudes. Even nearby (3.2 miles) KBUR with no major obstructions between I can only see flights when they hit above 5000.
I ordered an antenna from ScannerMaster too until I can get an SSE 1090SJ mk2
shipped over. I'll post results later today (Pacific Time, US) or tomorrow hopefully :-)

Getting the following polar with just the RB antenna on the roof about 25' up.
« Last Edit: October 09, 2008, 01:52:56 PM by oceans777 »

Terry

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Re: Not receiving many flights
« Reply #27 on: October 09, 2008, 01:56:22 PM »
Ok,
     Just put a P.S. on the last post for you,good luck and hope you get good results.

                           Regards Terry.

flightchecker

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Re: Not receiving many flights
« Reply #28 on: October 09, 2008, 05:26:30 PM »
Hi Terry and oceans 777
"mysterious" the "clicking", no idea, really don't know, never heard before !!!???

All of your "consultants" correct of course telling you to place the amplifier "as close to the antenna as possible". Otherwise (worst case at the end of the antenna coax [= the receivers input] ) noise, as generated by the coax itself as well will be amplified, thus degrading the "signal to noise ratio" of the signals as "seen" by the receiver. With other words, smaller signals will be masked by noise overlapping them.
This is the ONLY reason for the preamp to be mounted near to the antenna. Concerning its power requirements, it does not matter, whether it is situated at the antenna or at the receiver.
Positive supply voltage will be delivered via the coax's inner conducter, and negative via the outer (shielding) or even vice versa, depending on the preamps needs. Never mind about the amplifiers location in such a setup. The antenna itself of course won't see any supply voltage at all, as it is routed to the preamps INPUT. Its OUTPUT beeing "confronted" with the supply's voltage as delivered by the coax connected to it, simultanously of course beeing the signal path
to the receiver as well.
Finally again: no idea regarding the "clicking". If it was halloween I had, but still a bit too far away, isn't?

Anyway: have fun both of you. We've got a beautiful hobby, with or without "clicking" antennas (or preamps or coaxial cables or whatsoever)

Regards

Karl
« Last Edit: October 09, 2008, 06:00:03 PM by flightchecker »

Cumulus

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Re: Not receiving many flights
« Reply #29 on: October 09, 2008, 06:29:02 PM »
The clicking will be the bypass relay in the Elad preamp. Appears you may have insufficient voltage to activate it. Another thing to check is the DC plug to the Bias T, the size of the centre pin contact may be incorrect causing an intermittent supply.

Cheers,

Peter
« Last Edit: October 09, 2008, 06:32:31 PM by Cumulus »