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Author Topic: The third "SAW" filter..  (Read 11656 times)

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Speedbird London

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The third "SAW" filter..
« on: May 30, 2009, 04:54:57 PM »
Well, picked my 'box up from the parcel office this morning after it's THIRD repair trip to W&S, documented elsewhere; I'm getting quite good at this parcelling up malarky and on first name terms with the guy on the parcel desk.

Opened the box and the note from the engineer said he/she had fitted a new SAW filter.  I hope it's more durable than the previous two otherwise it'll be winging it's way back to them quite soon.

The polar diagram, after running for 45 mins or so, with the usual aerial is better than when it had been zapped but not as far reaching as when it was working well - What to do? - Return it saying it's not good enough or put up with it 'cos of the sheer unpleasantness of returning it, YET AGAIN?

I've got a co-linear aerial that I got from the US which will probably improve the performance but that's not really addressing the lack of sensitivity, is it?

The serial number is 107** so even if I got a new one it won't be any different.

(Yawn)

Ed


Allocator

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Re: The third "SAW" filter..
« Reply #1 on: May 30, 2009, 05:02:05 PM »
I'd give the polar diagram a bit longer to build up if I was you.  Even though atmospherics are not supposed to have much of an effect at 1090MHz, I do notice a difference from day to day.

I usually give it 3 or 4 days when I reset my polar diagram, as the amount of traffic out there obviously makes a difference too.

I'm sure you have answered this elsewhere, but are you doing anything unusual with your RB?  Standard antenna or external etc?

Speedbird London

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Re: The third "SAW" filter..
« Reply #2 on: May 30, 2009, 05:30:11 PM »
Yes, fair enough, 45 mins is not long to evaluate it but when it WAS working fine it would be showing better thqan now within several minutes, especially on saturday - I'm in North London with quite a view in most directions so not usually a problem from a radio point standpoint - ANYWAY, I'm going to give it 'til tomorrow night before I make a desicion about sending it back/asking for a refund or why..

Doing anything unusual? No, don't think so; the supplied little aerial on it's CD sized ground plane poked up, out of the window, as far as the supplied coax will allow, just above the roof-line.

I have a large Discone a few feet away, about three feet higher with which I can listen to the ground frequencies at LHR/LTN/LCY and STN so as you see it's a good radio location.

I'll wait 'til Sunday and see then.

Cheers

Ed

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malc41

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Re: The third "SAW" filter..
« Reply #3 on: May 31, 2009, 08:58:06 AM »
Ed

Please keep us updated, very interesting so far

15 Miles East of EGNJ

daveg4otu

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Re: The third "SAW" filter..
« Reply #4 on: May 31, 2009, 09:38:19 AM »
Doing anything unusual? No, don't think so; the supplied little aerial on it's CD sized ground plane poked up, out of the window, as far as the supplied coax will allow, just above the roof-line.

I have a large Discone a few feet away, about three feet higher with which I can listen to the ground frequencies at LHR/LTN/LCY and STN so as you see it's a good radio location.


The receive characteristics  of a discone operating  in the VHF or UHF airband are totally different  from those of the RB supplied  Magmount antenna .

5 Miles N of BHD at 50.28.28 N/3.30.43W...400ft amsl.

Hampshire, Devon, Dorset and Isle of Wight  Airfields Websites.....
http://devonairfields.tripod.com/index.htm

Speedbird London

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Re: The third "SAW" filter..
« Reply #5 on: May 31, 2009, 10:39:21 AM »
"The receive characteristics  of a discone operating  in the VHF or UHF airband are totally different  from those of the RB supplied  Magmount antenna"




I'm sure it is, I was merely making a point....

AirNav Support

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Re: The third "SAW" filter..
« Reply #6 on: May 31, 2009, 12:20:37 PM »
Speedbird,

The supplied antenna is a essentially an indoor antenna. While it can be used on mobile trips its is not meant to be placed externally for a long period of time.

It will end up being damaged by the elements as well as static on the antenna will build up after a few days in conditions and damage your SAW filter.

We strongly advice if you purchase an external antenna or an antenna which has an anti static design or you will face the same issues again.
« Last Edit: May 31, 2009, 02:04:05 PM by AirNav Support »
Contact Customer/Technical support via:
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Wayne

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Re: The third "SAW" filter..
« Reply #7 on: May 31, 2009, 01:59:25 PM »
Support

Can you just clear a few things up for me here ?

I use the supplied antenna on an outside window ledge as Pilkington glass in glazing kills the reception totally. Reading your comments it seems this is going to cause me problems at some point - have I interpreted this correctly ?

If I were to buy your external antenna kit would this give me protection against SAW damage or is there still a risk ?

Wayne


AirNav Support

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Re: The third "SAW" filter..
« Reply #8 on: May 31, 2009, 02:07:38 PM »
Hi Wayne,

The antenna is not designed to cope with the elements so after a while it will get damaged by water and you will start to see a reduction of what it picks up.

If you buy an external antenna which is has an anti static design and of course take precautions your self (to disconnect antenna during thunderstorms) then you should not have a problem like the vast majority of the customers using those setups.
Contact Customer/Technical support via:
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Wayne

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Re: The third "SAW" filter..
« Reply #9 on: May 31, 2009, 02:14:24 PM »
Thanks for that Support

Just one final thing then - does the antenna kit you sell have an anti-static design ?

Wayne


AirNav Support

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Re: The third "SAW" filter..
« Reply #10 on: May 31, 2009, 02:16:37 PM »
Yes our antenna kit is fine. There are other antennas which explicity say they have an anti static design as well which are also perfect for the job.
Contact Customer/Technical support via:
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flightchecker

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Re: The third "SAW" filter..
« Reply #11 on: June 01, 2009, 08:01:09 AM »
Quote
Yes our antenna kit is fine. There are other antennas which explicity say they have an anti static design as well which are also perfect for the job.

Wayne,
if I was you, the above would NOT satisfy my question: you've NOT been asking if the AirNav (external) antenna is FINE, you've asked if it provides an ANTI- STATIC DESIGN, haven't you?

Karl

AirNav Support

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Re: The third "SAW" filter..
« Reply #12 on: June 01, 2009, 08:17:06 AM »
Karl,

Maybe lost in translation, fine means its yes its good for the job.

But just to make clear, yes it has an anti static design.
Contact Customer/Technical support via:
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flightchecker

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Re: The third "SAW" filter..
« Reply #13 on: June 01, 2009, 08:32:17 AM »
Quote
...............But just to make clear, yes it has an anti static design.

Good to know and thanks for the "enlightment" AirNav. You won't tell how this is achieved, will you? The only "countermeasure" I am aware of is "DC Grounding", meaning to have a RF  chocke situated at the antennas feeding point, between its radiating element and ground. (RF allowed to pass [almost unattenuated] whilst DC [static components] depleted to ground / earth. The mast [that the antenna is mounted to and makes "ground contact" with] of course beeing grounded too) How about AirNavs antenna? Won't bother you, but highly intersted as a "confessing techie".

Kind Regards
Karl
« Last Edit: June 01, 2009, 10:47:45 AM by flight checker »

GlynH

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Re: The third "SAW" filter..
« Reply #14 on: June 01, 2009, 08:41:04 AM »
AirNav,

Without asking you to recommend one brand over another could you list examples of antennae that have an anti-static design please?

Thanks & regards,
-=Glyn=-