AirNav Systems Forum
AirNav RadarBox and RadarBox24.com => AirNav RadarBox and RadarBox24.com Discussion => Topic started by: marcdeklerk on October 22, 2009, 06:25:49 AM
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Good day all,
I was wondering how the A12-1090 Elad mast head pre-amplifier compare to the Kuhne KU LNA 1090 A TM Amplifier ?
Do I also need a Bias T to supply the power the KU LNA 1090 A TM Amplifier ?
-BT-12 Elad Bias Tee allows you to feed 12V to the A12-1090
wil this one work? - Bias-T MKU 271 N
these products can be found at : http://www.wsplc.com/acatalog/RadarBox-2009.html#a8960
and
http://www.kuhne-electronic.de/en
KU LNA 1090 A TM Amplifier mounted into a water resistant case, NF typ. 0.5 dB, Gain > 30 dB 163,00 €
which above unit has the greater gain? DBi or DB?
thanks and looking forward to advise
Marc
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Hello Marc,
I cannot answer your technical query and I'm sure some of the knowledgable guys will. I just want to say that I run the ELAD mast head pre-amp powered by the ELAD Bias-T (BT-12) and it works great for me.
If I disconnect the power supply I notice a decrease in my flights and the information being picked up.
I would recommend the set up.
Thanks,
Mark
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I had a problem with the ELAD, and it was replaced. In the meantime I bought the Kuhne, and that has been running perfectly for nearly a year - I think it is of better construction generally.
DC
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When you disconnect the power supply you have an attenuator ;)
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When you disconnect the power supply you have an attenuator ;)
Apparently there is a relay which bypasses the amp when the power is removed.
I received a faulty pre-amp with my antenna and when I apply power the pre-amp becomes an attenuator. Removing power and the Antenna alone works perfectly.
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Hi Marc, I'm far from expert, but the higher the DB figure, the higher the gain - DBI is a gain figure over an Isotropic antenna, as far as I know that is an omni-directional ("theoretically" perfect) antenna, with no nulls.
Pre-amps require a power source, which is usually 12v DC, directly connected by a psu in the case of the JIM M-75, or with external devices, such as the Elad or Kuhne which are mast-head amps, which get their power supplied through a Bias-T unit. A Bias-T box has a connector from antenna, output to the scanner, RB, SBS or whatever, and a socket for the 12v supply to be input, the 12v does not go to the output side at all, but is "pushed" up the feed from the antenna where it is received by the pre-amp. All extra connections incl. pre-amps and bias-Ts create some losses, and will also create some "noise of their own. Pre-amps come into their own, if used at the antenna, to overcome the losses incurred by longer lengths of co-ax. Also, bear in mind, if you've got a crap signal in the first place, a pre-amp isn't the cure-all some think, get the antenna and downlead sorted, would be my advice in the first instance, otherwise the pre-amp may just make the "noise" louder.
I hope this is of some assistance!
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which above unit has the greater gain? DBi or DB?
thanks and looking forward to advise
Marc the decibel (dB) is a measurement of ratio. It has no units and is a logarithmic scale. But there has to be a 'zero' to measure against.
This is called an isotropic antenna. It is a theoretical point antenna. If is was possible to exist it would look like a very small pea.
If an antenna has gain it could be compared to this theoretical antenna. If it's output voltage on receive was twice that of the pea, then it could be said to show a gain of 3 decibels.
But a practical term is required, so a dipole antenna is used as 'zero'. So an antenna with twice the voltage of a dipole would have a gain of 3 decibels. This is written as 3dB.
If the comparison was made against the pea it would be written as 3dBi.
As the the theoretical difference between a pea and a dipole is 2.1 dB this makes for confusion.
So an antenna advertised as 30dB would have the same gain as an antenna advertised as 32.1 dBi.
Does this help Marc?
Reg
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Thanks very much!
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Hello All,
My comments on the Elad 1090mhz Lna with the bias tree as follows.
1.Poor electronic and mechanicial construction.
2.Major U.K equipment supplier admits,this product is not very reliable
I returned my unit and a a full refund.
The KU LNA 1090 A TM Amplifier mounted into a water resistant case,no relays less (signal loss) and better construction and good technicial support.
Would be even better if there was a supplier in the U.K.
Paul
MW0CVW
near EGNR/EGGP
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Hi Paul, thank you for that, I'd heard the same re. Elad from another source, so would assume your assertions about the Kuhne (Rolls Royce) are spot on.
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John,
The Kuhne LNA is the Rolls Royce and would be my choice.
Not much cost difference (Elad) but a better product by far.
My profession for 25 years was in RF communications,so no quality and performace when i see it.
Hope this helps.
Regards
Paul MW0CVW.
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The KU LNA 1090 A TM Amplifier mounted into a water resistant case,no relays less (signal loss) and better construction and good technicial support.
Would be even better if there was a supplier in the U.K.
Looking on his ham pages
http://www.kuhne-electronic.de/db6nt/english/db6nt.htm (http://www.kuhne-electronic.de/db6nt/english/db6nt.htm)
one can see the quality of Michael's work.
But the 1090 is not in the price list.
As for the lack of a UK supplier, that should be no problem. I remember buying a German ATV transmitter kit in about 1971, when a pound sterling got over DM 9,0 and it arrived quickly.
These days with a credit card purchase (preferably Nationwide as their charges are much less) items arrive from Germany often faster that a UK supplier, in my experience.
Ironically, earlier today I was considering the opposite of a head amp. I monitor military aircraft and have alerts setup, so that I can be outside with my camera.
I can receive aircraft in/out of BZN which is over 200km from here, but no chance of seeing them. So I'm thinking of making a 3 element beam, pointing the other way or shielding the standard antenna that's on the window ledge.
Possibly a small 2 or 3 element beam pointing in the area of interest could provide a cheaper solution than a head amp.
Reg
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Hi Reg, there is a price list on his web-site KU LNA 1090 A TM (the exterior mast-head version in waterproof case) is €163.00 and the Bias-T KU BT 271N is €47.00.
It sounds as though you'd be better off with a colinear or dipole on a rotator, but that ain't going to fit on the window ledge! Have you thought about trying sticking a lemonade bottle over the standard antenna with length of self-adhesive aluminium tape down the side as a screen - if you haven't got any tape, PM me and I'll stick 30cm in the post. I used some many years ago on a Shakespeare homebase antenna - can't remember which model, but the whip was about 8' long and the lower section about 9½' long, the copper screen in the lower section for ground was pathetic, about 8 strands, which I removed and replaced with the aluminium tape wound spirally down the inner former - you can actually solder to the aluminium tape. I also built a replacement inductor trap, and turned a reasonably good antenna into a superb one.
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Thanks for your reply. I must be going blind !! I searched up and down umpteen times and never saw it, embedded in the ham amps. But in correct frequency order.
I like the suggestion of the bottle and aluminium tape. I just put the antenna on the window sill as I got it out of the box, intending to put it higher outside after weatherproofing it. But it works very well in that position.
Thanks for the offer on the tape, but I have some.
Reg
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so would a digital tv masthead amp work? 32db gain unit with f type connectors, i know the freq only goes to 860mhz but should still boost the signal?
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so would a digital tv masthead amp work? 32db gain unit with f type connectors, i know the freq only goes to 860mhz but should still boost the signal?
You gave the answer by yourself: The amp is designed frequencies up to 860MHz. Above this frequencies amps usually going relatively quick from amplification to attenuation. Further these amps usually allowing a higher Signal noise than the amps specially designed for our needs (high gain, narrow bandwidth, low noise, Installation in the "wild weather"). Further the CA-TV or SAT-TV amps are designed for Signal-Modulation-Types, which may cause additional negative effects too.
EDIT: I just forgot: TV has an Cable-Wave-Resistance of 75Ohm, RB and the 1090MHz Antennas using 50Ohm. Connecting 50Ohm to 75Ohm will produce reflections and interferences, which both are very bad for the Signal you want to receive.
Short:Better you keep your hands off from such experiments. ;-)
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ROGER THAT THANKS FOR THE INFO, I CANT SEEM TO FIND A AMP UNDER 150 AUD damn caps lock..sorry.
Anyone know where to get one at a decent price?
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Hi Jaskel, as stated on your other post a pre-amp will only boost signals , so are best used to overcome losses on a long co-ax run.
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Hello,
I must comment on the general electrical and mechanicial construction of the ELAD mast head amplifier and bias tree was poor.
The first unit received from W&S was faulty which was returned and replaced.
The second unit worked for about two weeks then failed.
I returned this back to W@S for a full refund.
The system has now been replaced with the Kuhne LNA 1090MHZ mast head amplifier and bias tree.
This system has a better noise figure then the Elad and additional band pass filtering on the pre-amplifier antenna input, so out of band signals (1090mhz) will not be amplified and reduce amplifier performance.
Kuhne also added some additional static protection on the amplifier RF stages and advised an antenna with DC ground would be the preferred option.
far better mechanical construction for outside applications.
I have posted polar diagram showing my coverage using the SSJ 1090MHZ antenna system.
Hope you find these comments helpful.
Kind Regards
Paul
MW0CVW
EGGP/EGNR
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Hi everybody,
After trying the JIM M75 amp without success I ordered a KU LNA 1090 A TM amplifier.
I have a question regarding the length of coaxial cable between antenna and amplifier….which is the optimal length ? I read that the usually length is 1m , is a problem if the length is shorter or a bit longer ? Also I would like to know if the type of coaxial cable used between the antenna and amplifier have to be the same type with the coaxial used between amplifier and power supply or I can use also other type of 50 Ohm low loss coax ? I am afraid that the length of cable that I bought is not longer enough to use it also between amplifier and antenna.
Thank you very much
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From antenna to pre-amp the cable needs to be as short as possible without putting any strain on to the connectors. About one metre ought to be sufficient. A high quality low loss cable should be used.
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Dana,
I am not surprised the performance to the Jim 75 amplifier was poor as this is a broadband amplifier with high noise figure.
The KU LNA 1090 which is be signed for mast antenna mounting, and with the bias tree located at the bottom of the coax you can power the LNA via the coax cable NO ADDITIONAL WIRES FOR POWER (12V) REQUIRED.
Buy the best coax possible LMR 400 (15m) or Echo Flex cable run from the LNA to the Airnav receiver is 15 meters.
LMR 400 from the antenna (SSJ) to the KU 1090 LNA amplifier.
This cable length is about 1.5 meters which includes a drip loop and N-type connectors rubber covers to stop any moisture ingress via the coax into the RF Connectors.
Don't have to be to critical on cable length above within a couple of meters will be fine.
The LNA small bandwidth good gain and low noise figure will improve your reception and take coax cable losses of signal into account.
Hope this information helps you out.
Regards
Paul
mw0cvw
EGGP/EGNR
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thanks guys :)
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Hi,
I just installed a KU LNA 1090 pre-amp and unfortunately I noticed a important loss of signal then before without pre-amp, shorter distance and less contacts with about 10-15%. I am using 10 m of Ecoflex 10 and GP1090 antenna outside about 17m high no obstacles around . Can anyone give me an explanation for that less contacts , please ?
Thank you.
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I had this initially with a second hand pre-amp and in my case it turned out to be the power supply.
The bias-tee needed centre + supply but the one supplied was centre -
So just check that you have the correct type of power supply for it.
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I don't use any bias-tee, I feed the amplifier with direct power supply 12V as KU LNA 1020 allow it as an alternative instead to use a bias-tee.
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sounds like the supply u feed your amp is dead!
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sounds like the supply u feed your amp is dead!
... or wrong polarity ?
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Did you buy KU LNA BB 1020 A or the KU LNA 1090 A TM. The last one is a specially designed for narrow-bandwidth ultra low noise Amp for ADS-B signals, as the other Amplifier is a wide-bandwidth Amp with a higher noise figure and no out of band suppression.
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I am using a KU LNA 1090 A TM . The polarity is right one.....All connectors are O.K. So, I have no explanation for loss signal using pre-amp:(.
Maybe the short lenght of coaxial cable ( 10m Ecoflex 10) to be the reason?
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If you turn the pre-amp power off, do you see a difference in reception?
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If I turn the pre-amp power off, I have no more contacts on My Flights list and my RadarBox doesn't receives any signal....
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Hi guys
I use the Kuhne 1090Mhz LNA and the bias tree and get great results.
You have probably checked the following already.
1.All N TYPE connects are fitted correctly to coax with no Short or open circuit connections.
2.Rf input on amplifier (from antenna) and output to the (Airnav box/bias tree) are connected right way around.
3.If you have a multimeter (Avo) check the current drawn by the bias tree and amplifier via coax,should be less than 200ma.
4.There are no coax relay in the amplifier, so turning off the 12vD.C to the bias tree will cause the amplifier to act as an attenuator and vastly reduce signal range.
Note:This has been done as coax relays depending on the type can cause signal loss at 1090mhz.
When I first tested my Kuhne LNA the local contacts (my flights number increased) but it took a good 24 hours for the polar antenna plot to update and show the increase in range.
Hope my thoughts and comments may help you in sorting your problem.
Kind Regards
Paul
MW0CVW
EGGP/EGNR
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Hi Paul,
Thank you for your help, problem solved...Seems that the reason was the power supply with more than 200mA. I am using a power supply wih less than 200mA now and the number of contacts icreased with about 20%, also better and constant signal.
All the best wishes and many thanks for your advices :)
Regards,
Dana
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Dana,
Very pleased you have located the problem to the Bias tree 12volt supply.
I use a convention 13.8V supply (12v d.c) which has a current capacity of 4000ma (4-AMPS).
Bit of an over kill, but the supply never gets warm as its running 24/7.
I never use switch mode power supplies as the are very RF Noisy, and effect other equipment located in the same room.
any questions please drop me a message anytime.
Kind Reagrds
Paul
MW0CVW
EGGP/EGNR