AirNav Systems Forum
AirNav RadarBox and RadarBox24.com => AirNav RadarBox and RadarBox24.com Discussion => Topic started by: AllanK on July 26, 2009, 07:57:17 PM
-
I have just had my radarbox returned after suffering, what I assume was, static damage. Although the repair was lightening (no pun intended) quick - 3 days - I am not keen to suffer the damage again. The relevent FAQ says, to prevent this damage,:
- Purchase an antenna with an anti-static design
- Either attach a Mast amp which should bleed any excess static away and improve your reception.
- Either add a dc block (to bleed away excess static)
So, my questions are......
1. What antennas are of an anti-static design? What sort of designs are these? ( ie colinear, j-pole)
2. What is a good (and economical) mast amp - for protection, where the received signal is alread good? (my current 1/4 wave dipole receives good signals at the hieght it is at, but clearly (I presume) is not of a good anti-static design.
3. Where can I get a dc-block in the UK? - googling seems to return nothong of local asistance!
4. Can a high value resisitor be placed across the co-ax socket to bleed static to earth?
5. Should the radar box be earthed?
your replies will be read with interest. Thank you
--
Allan
-
Hi Allan,
I can recommend the SSE antenna and Kuhne preamp.
http://www.ssejim.co.uk/26-sseads1090sj.htm (http://www.ssejim.co.uk/26-sseads1090sj.htm)
http://www.kuhne-electronic.de/en/shop/143_Vorverstaerker/article:342_KU_LNA_1090_A_TM (http://www.kuhne-electronic.de/en/shop/143_Vorverstaerker/article:342_KU_LNA_1090_A_TM)
Regards,
Peter
-
Hi Allank
I live in a country (Brazil) thath is from far the mosr hitted with thunderstorms.
I have one RB with a homebriew antenna at the top of a 16 floor building and never disconnect anything even when a thunderstorm is overhead.
A second RadarBox (remote ...5 NM away) with homebriew antenna at the top of a 15 floor biulding...
As I do not have phisical access to it ....Also never is disconnecter from atenna no matther the wheather is..
I deal with RBs since lauched on market... have 4 at this time.... Never got one dameged, even when I did with RBs a lor of testings and also wrongly feeded one of them with 8 VDC... It is still working well here.
Detail : Both antennae are not grouded !!!!!!!!!!!!!!!!!
I do not beliene in goog or bad luck.... Maybe there are some other factors "destroying" your RB.
But if You suspect that some static is damagin your rb (I do not think it is the case), why not to try to use a lighting arrestot like those used in Wireless systems ?
Like this one :http://www.snappernet.co.nz/Packages/FernShopUni/FernShopUni/Pub.Shop.Product/PID/10BEE54F/LINK/Pub.Shop.Product_BTN_DETAILS10BEE54F/TYPE/details/ROOT/SNAPPER
Cheers from Brazil
-
Hi AllanK - if you search through forum you will find chapter and verse on this subject.
A great deal of the discussion centres round the "static" theory however there is considerable contrary evidence such as juangelb's brazilian account (above) and my own and other's experiences where aerials have been not been exposed to outside use together with other cases where the supplied aerial was in use in fact and indoors at that.
There is I suppose the possibilty of "human" produced static from nylon carpets etc. but in the absence of a clearly defined pattern one wonders whether we are seeing the occasional and totally random failure of a part fitted within the box? ie nothing to do with static?
Whatever the cause, I think I'm right in saying that Airnav have re-assured us that repaired boxes are subsequently failure-proof.
-
bratters the thought of 'human static' is interesting, but like yourself i am sceptic on the cause of this problem.
it is good to see Airnav response and their support for all users over the deaf boxes
-
Could I ask Airnav to confirm the S/N at which the enhanced protection is fitted in production?
The post I found in the original thread about this states 101500. That seems to have one digit extra. I couldn't decide whether it means 10150 or 11500.
-
Hi Fenris,
Sorry reason for the confusion as the login codes and RB serial codes are similar but the login codes are slightly longer.
It might make it easier if we said the login codes as they are linked to the serial.
If you enter anything above PGANRB101500 then it will be the new boxes.
-
Thanks for the replies so far. I am confused/concerned that even though my box is PGANRB1104xx, ie higher than the 101500, that it has still suffered damage. The fix was 'replaced SAW' so I assume it was static damage as there was no lightening around.
So do I need extra protection (dc block) or not - I am still not sure. Is the current 'fix' more robust than even the 110000+ units and therefore not needing any further protection?
--
Allan
-
Glad you're back in business Allan. Only Airnav themselves can answer your questions - the rest of us, like you, are guessing.
-
Allank,
Please read:
http://www.airnavsystems.com/forum/index.php?topic=2759.0
-
Please read:
http://www.airnavsystems.com/forum/index.php?topic=2759.0
Thanks for the link. I think that I need to provide some extra protection to my investment if it is to remain on 24/7 with an outdoor antenna.
Therefore I welcome any information on UK sources of dc-block, masthead amp that will be good for 1090Mhz. Better safe than sorry
--
Allan
-
Please read:
http://www.airnavsystems.com/forum/index.php?topic=2759.0
Thanks for the link. I think that I need to provide some extra protection to my investment if it is to remain on 24/7 with an outdoor antenna.
Therefore I welcome any information on UK sources of dc-block, masthead amp that will be good for 1090Mhz. Better safe than sorry
--
Allan
Me too, I would prefer the block though as I am not pulling my mast down again.
-
But if You suspect that some static is damagin your rb (I do not think it is the case)
What then do YOU think it is, juangelb, any idea? There is no known “voodoo” in electronics.
why not to try to use a lighting arrestot like those used in Wireless systems ?
Like this one :http://www.snappernet.co.nz/Packages/FernShopUni/FernShopUni/Pub.Shop.Product/PI
D/10BEE54F/LINK/Pub.Shop.Product_BTN_DETAILS10BEE54F/TYPE/details/ROOT/SNAPPER
"Lightning Protection" may not be mistaken with "Static Protection" juangelb. The “lightning arrestor” your link is pointing at, has (what is called ) a "breakdown voltage" of 90 ! Volts DC, (there are others available with other “breakdown- / threshhold- levels”) and only in case this "threshold” is overriden. it "fires", thus shortening (for instance) a receivers input to ground / earth (assuming of course “ground” has been provided to the "arrestors” terminal respectively) to prevent “ligtning energy” from destroying the (receivers) input circuitry.
ESD (Electro Static discharges) well below this "threshold" might even be harmful, though
not always “instantaniously”, but due to known “long term effects”, that degrade a receivers performance (sensitivity) "over time". (*)
DC Blocks, as well not a measure against the subject to talk about, and (among many other threads in this forum) discussed here: http://www.airnavsystems.com/forum/index.php?topic=2746.0 in Reply # 29.
The antenna mentioned by Cumulus (Excellent suggestion!) above is the only one I know to have a “DC grounding design”. It must be grounded / connected to earth of course to comply with its design, and an almost cost intensive (“protecting only”) preamp with its accociated components may then not even be required.
All of the above discussed “in a lenght”, (as AirNavs uses to say) and pointing at professional sources covering the subject, stating that SAW filters in a receivers input are suspective to ESD (Electrostatic discharge) as are other solid state devices in other applications, and carefull protecting measures must be applied to prevent harm to them.
AirNav said they have done so for the latest batches of RBs and will “modify” earlier receivers if their input SAW device have suffered from ESD strokes:
http://www.airnavsystems.com/forum/index.php?topic=2675.msg23352#msg23352
Reply #3
Regards
Karl
(* edited 29.07.09 / 17:45)
Filter manufacturers will typically specify DC voltages between 0 and about 20 Volt DC ! allowed to be applied to their SAW devices as a maximum.
K.
-
OK flight checker
Thanks for all the info.
Cheers
-
Glad you're back in business Allan. Only Airnav themselves can answer your questions - the rest of us, like you, are guessing.
hi all
I think people are to quick to jump on airnav on this static problem, did your ever think
carpet in your room is good starter for static, and a lot more things,
i have had my arinav 7 months now outdoor aerial no static damage,
if everyone was coming down with static problems yes its the airnav box fault.
The vultures from another forum prey heavily on this subject, to take airnav down.
But its only a very small few boxes that have the problem, so you have to say its something else that is causing the static build up, but what i do not know, well that is my thoughts for today
from pat
-
I now have a DC block, Just need to check its ok on the Radarbox, When I get it back.
-
I now have a DC block, Just need to check its ok on the Radarbox, When I get it back.
Where did you get it ?
-
Sounds interesting
-
I now have a DC block, Just need to check its ok on the Radarbox, When I get it back.
Where did you get it ?
After looking online for inline SMA blocks, a) I could only find them in the US and b) They are VERY expensive at that, I decided to make one at work, It has BNC connectors so I will be using adapters, I should have my RB back from repair today so will try it with and without to see how if at all it is affected, My scanner is not affected at all with any signal loss, But I don't listen to anything at 1090MHz.
-
After looking online for inline SMA blocks, a) I could only find them in the US and b) They are VERY expensive at that, I decided to make one at work, It has BNC connectors so I will be using adapters, I should have my RB back from repair today so will try it with and without to see how if at all it is affected, My scanner is not affected at all with any signal loss, But I don't listen to anything at 1090MHz.
That's the problem I had looking. I look forward to your tests and then perhaps you can share construction details?
-
Hi velcrohead and AllanK
A DC Block inserted into your receivers input will not of course noticeable degrade the performance of the latter, PROVIDED its design specifications meet the receivers frequency operating range and input impedance.
A “homemade” realization of such a device must be considered very carefullly, as the frequency it is supposed to handle is almost 1090MHz ! The capacitors “RF behavior”, as well as its housing (“to behave strictly coaxial” of course) must be in accordance with the RF rules that are indispensable at the frequency it is about. Otherwise, and among others, impedance mismatch might occur, resulting in an increased SWR (Standing Wave Ratio), all of those finally degrading / attenuating the signal “seen” by the receiver.
Following my posting that I’ve been mentioning in reply #12 you will be given an answer, what a DC Block is supposed to be, and really supposed to be for. To repeat myself once more: if in doubt, “google for DC Blocks”, and you may find out about the above yourself. You’ll not find one ! manufacturer, that claims his DC Block to be a ESD protection measure. (He might get into trouble otherwise) You will even find the “blocks” specified for typical “max Input voltages” of 100V DC only, a “nothing” as compared to the potential, ESD voltages may rise up.
Regards
Karl
-
After looking online for inline SMA blocks, a) I could only find them in the US and b) They are VERY expensive at that, I decided to make one at work, It has BNC connectors so I will be using adapters, I should have my RB back from repair today so will try it with and without to see how if at all it is affected, My scanner is not affected at all with any signal loss, But I don't listen to anything at 1090MHz.
That's the problem I had looking. I look forward to your tests and then perhaps you can share construction details?
If all is ok, I certainly will, although it is nothing complicated.
-
Hi velcrohead and AllanK
A DC Block inserted into your receivers input will not of course noticeable degrade the performance of the latter, PROVIDED its design specifications meet the receivers frequency operating range and input impedance.
A “homemade” realization of such a device must be considered very carefullly, as the frequency it is supposed to handle is almost 1090MHz ! The capacitors “RF behavior”, as well as its housing (“to behave strictly coaxial” of course) must be in accordance with the RF rules that are indispensable at the frequency it is about. Otherwise, and among others, impedance mismatch might occur, resulting in an increased SWR (Standing Wave Ratio), all of those finally degrading / attenuating the signal “seen” by the receiver.
Following my posting that I’ve been mentioning in reply #12 you will be given an answer, what a DC Block is supposed to be, and really supposed to be for. To repeat myself once more: if in doubt, “google for DC Blocks”, and you may find out about the above yourself. You’ll not find one ! manufacturer, that claims his DC Block to be a ESD protection measure. (He might get into trouble otherwise) You will even find the “blocks” specified for typical “max Input voltages” of 100V DC only, a “nothing” as compared to the potential, ESD voltages may rise up.
Regards
Karl
Hi Karl, good advice, I do of course already know all of this, being in electronics test for quite some time, and a fully licenced radio ham, I am merely trying to reduce any future problem, I cannot test my box unfortunately as the test gear we had to do it has been moved to France.
My Radarbox has not shown up either rather worryingly.
-
Appreciating your comments, velcrohead
Karl
-
Appreciating your comments, velcrohead
Karl
I hope my reply wasn't taken the wrong way Karl, I know sometimes they can be on forums/email etc.
Cheers.
-
NEVER EVER !!! velcrohead
cheers, and have a nice weekend,
Karl
-
NEVER EVER !!! velcrohead
cheers, and have a nice weekend,
Karl
Ok, good, I still cannot test my little box of tricks as I don't have my RB back yet.
-
For those among us, that even always wanted to know what a “SAW Filter” physically looks like check here:
http://www.cts-kenwood.cz/kv/Klinovec/
(parent directory / overwiew)
http://www.cts-kenwood.cz/kv/Klinovec/airnavuvnitr.jpg
ANRB (inside „ black box“)
http://www.cts-kenwood.cz/kv/Klinovec/uvnitr1024c.jpg
&
http://www.cts-kenwood.cz/kv/Klinovec/airnavvstup.jpg
SAW devices "in detail" (> F1 / F2 / F3)
http://www.cts-kenwood.cz/kv/Klinovec/panorama1024.jpgpanorama1024.jpg
WISH I WAS HERE……………………………………………………………..
(And explaining of course the [parent directories] excellent ANRB screenshots, that most of us probably will keep on dreaming for the rest of our life......it's a shame, isn't it..........
Karl
-
Some nice pictures there Karl, Thanks.
-
Ok, good, I still cannot test my little box of tricks as I don't have my RB back yet.
Rather interested in some more details on that if you've finally realized your testing, velcrohead.
If interested in my "provision against ESD harm" contact me via e-mail. Should be easy to realize for you, knowing you're a HAM, but may at least be matter of interest.
Karl.
-
Ok, good, I still cannot test my little box of tricks as I don't have my RB back yet.
Rather interested in some more details on that if you've finally realized your testing, velcrohead.
If interested in my "provision against ESD harm" contact me via e-mail. Should be easy to realize for you, knowing you're a HAM, but may at least be matter of interest.
Karl.
Not had a chance to do any testing unfortunately Karl, I will only be able to do a 'plug it in and try' test at the moment, I should hopefully have my RB back tomorrow.
Do you have any info on your website?, Always interesting to read all articles about anything.
PM me if you prefer.
-
For those among us, that even always wanted to know what a “SAW Filter” physically looks like check here:
http://www.cts-kenwood.cz/kv/Klinovec/
(parent directory / overwiew)
http://www.cts-kenwood.cz/kv/Klinovec/airnavuvnitr.jpg
ANRB (inside „ black box“)
http://www.cts-kenwood.cz/kv/Klinovec/uvnitr1024c.jpg
&
http://www.cts-kenwood.cz/kv/Klinovec/airnavvstup.jpg
SAW devices "in detail" (> F1 / F2 / F3)
http://www.cts-kenwood.cz/kv/Klinovec/panorama1024.jpgpanorama1024.jpg
WISH I WAS HERE……………………………………………………………..
(And explaining of course the [parent directories] excellent ANRB screenshots, that most of us probably will keep on dreaming for the rest of our life......it's a shame, isn't it..........
Karl
Interesting...
Some comments on RF layout:
very high gain, third SAW may become overloaded on close traffic
not enough ground vias in my view, especially close to devices, may generate problems to discharge static
antenna dc-coupled to SAW filter, not seen that before, no capacitor, no esd-diodes - strange
I would recommend to solder a 10pF capacitor between the antenna and the first SAW and apply 2 ESD diodes or a 1 MOhm resistor from antenna to ground.
(I would assume this is an earlier design)
-
With regard to this, Does anyone actually know which SAW gets replaced?, all or one or 2?.
From Palmar's comment, it would be interesting to know.
-
I can only imagine the front end SAW be damaged by ESD.
The overload I mentioned is likely for the third one, but has nothing to do with ESD. As the signal gets "over"amplified data may become distorted by interception and unreadable for the following decoder. The overall gain of the frontend is around 43 dB, which is 20000x (compare to 27 dB (500x) on the other product).
-
I can only imagine the front end SAW be damaged by ESD.
The overload I mentioned is likely for the third one, but has nothing to do with ESD. As the signal gets "over"amplified data will become distorted and unreadable for the following decoder. The overall gain of the frontend is around 43 dB (compare to 27 dB on the other product).
Front end SAW damage is what I thought, I just wish I had mine to try, I had a few hours of use with V3.01 software, The performance was definitely better, But then I had the dreaded problem.
-
I can only imagine the front end SAW be damaged by ESD.
The overload I mentioned is likely for the third one, but has nothing to do with ESD. As the signal gets "over"amplified data may become distorted by interception and unreadable for the following decoder. The overall gain of the frontend is around 43 dB, which is 20000x (compare to 27 dB (500x) on the other product).
Well it's an AM pulse modulated signal, so there is no real possibility of overload, the time constant of the amplifiers is very short, the only thing that matters in that respect is the log amp after the 3rd SAW. That will have a recovery time that is somewhat longer because it's designed to hold the gain constant across the data packet instead of between data bits. It's this that means that a weak transmission immediately after a stronger one may be missed because the log amp doesn't see it.
The SAW itself doesn't saturate, the only risk is if a very high signal level is present it just might damage the transducer metallisation on the surface of the die.
That is the same failure mechanism as caused by a static discharge, although in that case the energy is much higher and the current so high that it vaporises the metal of the transducer (which is only a few microns thick).
-
You may judge from the datasheet yourself whether the gain is too high or not. The attenuation out of band is 30 dB only, with high energy bands in the immediate vicinity (GSM). Any non linearity in the path will be grateful taken.
http://www.golledge.com/pdf/products/specs/ma04282.pdf
(Look at the maximum DC voltage, compared to the missing capacitor of stage 1)
The logamp recovery is not an issue I believe (less than 100 ns per datasheet). But the amplified noise floor may give it a hard time as it will start to see a signal at -70 to -80 dBm.
In summary I would think that bridging the second 24Z MMIC would yield the same if not better reception quality. What do you think?
-
Do you have any info on your website?, Always interesting to read all articles about anything. PM me if you prefer.
@ velcrohead
Unfortunatetly don't have my own website, no need for it so far. Would have to attach a few pictures for the "item" it is about. PM won't do. So, if still interested, proceed via e-mail.
Kind regards
Karl
-
Hi fenris and palmar,
interesting to follow your theories, but it’s “theories” finally “as long as it works”, which it obiously does.
I was more concerned about the “naked” (unprotected) F1 SAW device (galvanically coupled to the antenna input by a stripline matching stub), which, as a highly sensitive device, literally must be “scared to death” in the attendance of ESD tensions.
At least I might now understand AirNavs frequently recommendation for a “DC Block”, that I expected to be part of the frontend design of course, and to be realized by a “capacitor” as mentioned by palmar. Though not a good insurance against ESD harm, it appears to be even “ better than nothing”. And, as an “integral part” it would almost have cost “a nothing”, as compared to an external (commercial) device, whose specifications have to be paid for, though not needed in this type of “application”. It simply serves for measurement purposes in higher qualified applications, as discussed before.
I agree with palmar, that AirNav have considered the above regarding their later batches of RBs. They say so themselve.
Future will show, if the preventive measures, that obviously have been taken, will result in a lower yield of receivers to fail.
I personally would prefer “helical filter arrays” in a receivers frontend as their design is of a “mechanical” rather than “solid state” nature, the latter beeing highly sensitive to ESD as mentioned many times on the occasion of preceeding postings, if not by the manufacturers of those SAW devices themselve. SAWs obiously are a cheaper solution.
Karl
-
Do you have any info on your website?, Always interesting to read all articles about anything. PM me if you prefer.
@ velcrohead
Unfortunatetly don't have my own website, no need for it so far. Would have to attach a few pictures for the "item" it is about. PM won't do. So, if still interested, proceed via e-mail.
Kind regards
Karl
Ok Karl, Many thanks for that.
-
You may judge from the datasheet yourself whether the gain is too high or not. The attenuation out of band is 30 dB only, with high energy bands in the immediate vicinity (GSM). Any non linearity in the path will be grateful taken.
http://www.golledge.com/pdf/products/specs/ma04282.pdf
I believe the devices used are not made by Golledge, the logo on the SAWs would suggest that they are TaiSAW devices.
Even then what matters is the total attenuation out of band before the log-amp, provided that there is enough attenuation per filter then it will take a very high level from other services to cause a problem in each stage.
You need to look at the first device, it has the code AAAV on it IIRC, not sure whose that would be but a search should find it.
edit: It's a Maxim MAX2640. Input IP3 intercept is -10dBm, so if you allow for the filtering action on say GSM, of 30dB, then that would increase by at least 20dB which would be enough for all but the very strongest GSM signals.
(Look at the maximum DC voltage, compared to the missing capacitor of stage 1)
The logamp recovery is not an issue I believe (less than 100 ns per datasheet). But the amplified noise floor may give it a hard time as it will start to see a signal at -70 to -80 dBm.
In summary I would think that bridging the second 24Z MMIC would yield the same if not better reception quality. What do you think?
Well I would hope that Primetec did some measurements to see whether there was any compression at sensible signal levels at each stage. But by the time you get to stage 2 then the filtering should already have done away with all but the wanted signals.
If you want to know about the system performance, then take the losses and gains of the 3 stages and do a cascaded gain/noise figure calculation. It will tell you how much SNR you would lose by removing that third stage.
-
Golledge is the UK distributor for Taisaw-
-
Golledge is the UK distributor for Taisaw-
Fair enough, I haven't used a SAW filter in years, all the radios I'm involved in these days are all-silicon and don't tend to have bandpass filters.
I didn't actually check the data sheet you mentioned, if it is for that particular part then the numbers you quote will apply. Oh yes, I see, it's a TA1090EC. Golledge just give it a different part code.
-
http://www.cts-kenwood.cz/kv/Klinovec/SGA-2486(Z)_Datasheet%2024Z.pdf
Hi Karl, many thanks for the link to this data sheet, these are the same little b*ggers that are used in Optoelectronics Scouts, and seem to get overloaded and low at the first opportunity - they charge $15 each for them (not including labour and shipping which is another $100+. I did buy 2 to replace the duffers in my Spectrum Scout, which will go on eBay, once I'm satisfied it is 100%, as I've bought myself one of the Digital Scouts. I'm amazed at the extra frequencies it detects, which I hadn't realised were in use all around.
-
Read with great interest Jon, thanks so much !
Karl