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Thread: FRSKY - WARNING !!!!!!

  1. #1
    Pilot Dionysos's Avatar
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    Exclamation FRSKY - WARNING !!!!!!

    Hi guys,
    for a while I have been using FRSKY, it usually works great and the price is unbeaten. Unfortunately I stumbled across 2 !!!!VERY!!!! important things that I would like to share with you to make the system more reliable.

    I had to learn it the hard way: My holiday FPV plane lost in the Phillippino jungle - no way to recover it - due unexpected fail safe maybe ~400m away with the FRSKY patch antenna. Impossible? Well I figured out what happened and I would strongly encourage other users to take the necessary follow up to avoid this problem. It will take 30min and save you a lot of trouble.

    Besides I wrote to FRSKY support, i.e. explaining the problem. Let's test their customer support.

    I will keep you posted.

    Here is the email:

    Hi Eva,
    I recently purchased the set FRSKY set with a D8R-II RX and DFT TX module. Also, I purchased the FLD-02, Sensor Hub and battery voltage sensors, GPS – a lot of things from you guys. However I had quite a few issues which led to the loss of my most appreciated FPV aircraft: I was flying a few 100m away in an rf low noise area. All of a sudden the tx started to beep indicating a signal loss, RSSI close to 0 and went into failsafe. I had no chance to recover the plane as it crashed in the jungle. On board were video cameras, video transmitter and a few other gadgets. I couldn’t believe what happened and checked the TX module. As the picture shows, the ground got disconnected/got broken. This is clearly a very weak spot in the tx side and probably after swapping the module a couple of times, other users will run into the same issue. It took me some fiddling but I managed to properly reinforce the weak spot to ensure a lasting and proper connection. I would strongly encourage you to improve the design of this connection. I have my patch antenna mounted away from the DFT module, connected through a proper coax extension. Without the ground, the antenna length match was off – completely – resulting in the range loss. Doing a ground check may not even have solved this simply because it’s an on off problem: sometimes there will be contact sometimes no, simply because the gap is no more than 1mm.

    Prior to this, I already had some issues regarding this connector as shown in the picture. It came loose and had to be manually resoldered. Gladly I noticed this before flying. Clearly this spot again shows poor manufacturing in terms of soldering spots.

    I would appreciate you evaluating on the discussed issues and what you are going to do in future to avoid these kind of problems. I like the FRSKY products very much and I would like to continue to use them. Regarding the loss of my plane which cannot be recovered, maybe you could find a way to make this up to me again.

    Hoping to hear from you soon.

    So in one of the pics, you see that the antenna ground between coax and rp-sma is prone to break easily. I also read up and heard that other users encountered a short between the ground and the signal wire due to overheating the sig-wire when soldering: from the manufacturing side.
    I mount my antenna away from the DFT, so I need a short coax extension. If the ground plane is missing like it was in my case, I wonder how it even made it that far away. It's an ON/OFF problem not so easy to detect, so please check on yours to make sure.

    Other than that, the 4-pin connector that connects the HF module came loose after inserting the module maybe 2 times. Please re-solder this connector and secure the plastic cover (the black one) with either CA or hotglue.

    After all, I still like this system, but try to double-check on the items dicussed.

    I hope it helps,

    Dio
    Attached Thumbnails Attached Thumbnails Click image for larger version

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  2. #2
    could quit if I wanted to volto's Avatar
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    Dang sorry about your lost plane, that sucks. I will certainly check the connections on mine, thanks for the heads up.
    Don't steal, the government hates competition.

  3. #3
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    Man is that crappy coax on the antenna. It's all fun and games untill you loose a plane. Sorry for your lost. You can also change it for a better cable. http://parts.digikey.com/1/parts/185...ma-ufl-10.html this a rp-SMA version.
    Last edited by Martin Y; 16th April 2012 at 05:27 PM.
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  4. #4
    GO HAWKS Hucker's Avatar
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    Probably would be a good idea to have FrySky pilots range check diligently before flight, especially when flying over unrecoverable areas like water, jungles and other dangerous terrain.

  5. #5
    Test pilot addict airtruksrus's Avatar
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    I had the same problems with the ufl connectors on the receiver, not on the tx module yet. Not going to mess with it untill it starts giving me problems. I did have a crash while i was using the 7dbi patch on the tx and changed out ot an argtek amp and a 9dbi whip, managed to fly out 1 mile yesterday with no issues.
    KF7TSE

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  6. #6
    Pat h0tr0d's Avatar
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    Keith took apart his frsky patch and found they used a metal screw that shorted the active element and the reflector together. You guys might want to check that too. I don't think he has published his results yet, but was able to confirm that removing that metal screw gave him better range on ground tests.

  7. #7
    Pilot Dionysos's Avatar
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    Hi,
    thanks for your support!

    @hotrod and all other patch antenna users: I took my original patch apart and what I saw there really made me cry. Those engineers must have been very drunk. Have a look:
    The antenna pic1
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    ... and opened pic2
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    ehh, wait! Do you see the silver sticker in the first pic?! This one is supposed to be FRONT. As you can see from picture 2, they labeled it wrongly. Another reason for the reduced range?!

    What else is there?
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    hmm. The screw in the middle is definitely causing a short between SIG and GND, however, that might explain why I got "some kind" of signal out of this thing, when operating the antenna in the wrong direction due to wrong labelling. Obivously we a looking at a coax edge-fed antenna. The holes in the ground plane / metal sheet, the strange shape of the patch element remind us that this could be done way better, but metall seems to be conductive and forgiving.

    Let's do a test:
    http://www.emtalk.com/mpacalc.php

    h~2.5mm
    epsilon(r) of air: 1.000896

    L=48mm <== these I measured with a ruler, values from the patch
    W=41mm

    L(sim)=57.67mm
    W(sim)=61.10mm

    hmm again, seems off. maybe the e(r) was a bit too small, after some playing with e(r) values. I ended up using 1.5, which gives me a center frequency of 2.45Ghz. Seems good, taking into consideration that polymers are somewhat increasing this number, seems half-way plausible. Unfortunately the input impedance is now 200Ohms. Never mind, 9v input should make a current of 60mW flow (specs by FRSKY). based on this simulation, only 45mA are going through, so well, not sure if the guys thought this through properly. Maybe my calc's are wrong.

    Anyways, there shouldn't be a connection between SIG and GND. I'm gonna remove that and run a few tests.

    Summary:

    1. STICKER PLACED ON THE WRONG SIDE: MIXED UP FRONT AND BACK!!

    2. SHORT BETWEEN ANTENNA SIG AND GND (caused by screwmount)

    Now please, some experts enlighten me, but to me this stinks.
    Latest Crafts: Guava 2m, Wunderwaffe, Uberwaffe, Plankton v2, TBS discovery

  8. #8
    Pilot Dionysos's Avatar
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    Ok,
    something more. Eva answered, a very fast reply, they are offering a new system. I'm ok with that deal, what else can I say? Does it boil down to the point where people say: "ahhhhhhhh, why bother? it's only 50US$ system, what can you expect?"

    I think everybody has to answer this one by themselves. I still find this system handy and after having played with it, I get to know its flaws better.

    Dear xxxx[edited],
    Thank you for your e-mail/feedback and sorry for your loss.

    I checked enclosed pictures and discussed with R/D and production depts this morning. We knew from the picture of "connector DFT" that the dropped connector was old type connector, which we have improved and replaced by Molex connector since end of last year to give more secure connection. Also new batch for IPEX70 ("broken ground") has more flexibility. Franklly speaking, IPEX70 is not so easy to broken unless some re-modification is done to it, you are the first report back.

    [edited:name blanked], I will go and apply another new set of telemetry system for you, and hope you will give us more suggestions in the near future if possible. How about DHT-U telemetry module with in-built LCD display and on-screen setting which will have data log function since V2.1 firmware?

    I am looking forward to hearing from you soon.
    Many thanks and best regards!
    Eva
    I shall definitely let them know about the antenna and keep you posted about the reply, maybe I overlooked something, but I would like to have some clarification, too.

    Cheers,
    Dio
    Latest Crafts: Guava 2m, Wunderwaffe, Uberwaffe, Plankton v2, TBS discovery

  9. #9
    could quit if I wanted to volto's Avatar
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    That's excellent news. I am glad they support their products unlike most chinese companies.
    Don't steal, the government hates competition.

  10. #10
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    Reguarding the screw from patch to ground. That is a DC short not a AC(RF). The antenna will behave differently with or without the screw.
    I'm Not Crazy.....My Mother Had Me Tested.

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