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Author Topic: Static Damage Prevention/Protection  (Read 25654 times)

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velcrohead

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Re: Static Damage Prevention/Protection
« Reply #30 on: July 30, 2009, 04:26:58 PM »
Quote
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.

palmar

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Re: Static Damage Prevention/Protection
« Reply #31 on: July 30, 2009, 05:17:21 PM »
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)
« Last Edit: July 30, 2009, 05:19:00 PM by palmar »

velcrohead

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Re: Static Damage Prevention/Protection
« Reply #32 on: July 30, 2009, 05:20:51 PM »
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.

palmar

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Re: Static Damage Prevention/Protection
« Reply #33 on: July 30, 2009, 05:41:25 PM »
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).
« Last Edit: July 30, 2009, 05:45:18 PM by palmar »

velcrohead

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Re: Static Damage Prevention/Protection
« Reply #34 on: July 30, 2009, 05:43:56 PM »
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.

Fenris

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Re: Static Damage Prevention/Protection
« Reply #35 on: July 30, 2009, 10:20:10 PM »
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).

palmar

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Re: Static Damage Prevention/Protection
« Reply #36 on: July 31, 2009, 04:57:35 AM »
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?

« Last Edit: July 31, 2009, 05:09:43 AM by palmar »

flightchecker

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Re: Static Damage Prevention/Protection
« Reply #37 on: July 31, 2009, 07:36:33 AM »
Quote
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
« Last Edit: July 31, 2009, 07:38:50 AM by flight checker »

flightchecker

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Re: Static Damage Prevention/Protection
« Reply #38 on: July 31, 2009, 10:01:28 AM »
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
« Last Edit: July 31, 2009, 10:20:48 AM by flight checker »

velcrohead

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Re: Static Damage Prevention/Protection
« Reply #39 on: July 31, 2009, 11:51:25 AM »
Quote
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.

Fenris

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Re: Static Damage Prevention/Protection
« Reply #40 on: July 31, 2009, 03:49:04 PM »
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.


Quote from: palmar

(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.
« Last Edit: July 31, 2009, 03:56:08 PM by Fenris »

palmar

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Re: Static Damage Prevention/Protection
« Reply #41 on: July 31, 2009, 07:23:40 PM »
Golledge is the UK distributor for Taisaw-

Fenris

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Re: Static Damage Prevention/Protection
« Reply #42 on: July 31, 2009, 08:04:44 PM »
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.

CoastGuardJon

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Re: Static Damage Prevention/Protection
« Reply #43 on: August 11, 2009, 10:52:16 AM »
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.
« Last Edit: August 11, 2009, 10:57:10 AM by CoastGuardJon »
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!

flightchecker

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Re: Static Damage Prevention/Protection
« Reply #44 on: August 11, 2009, 04:07:25 PM »
Read with great interest Jon, thanks so much !

Karl