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Jittery 35meg set


Olly P
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OK, test results so far. See what people think....
 
First the Wot 4 Foam E as the 'base' aircraft, using the chl 71 xtals. all my Xtals are Futaba's. BTW. The servos are the standard ones supplied with the Wot 4, the ESC is the replacement one sent after the original had a fault.
 
OK first the Corona Synth Rx.
 
One ESC/BEC power twitching started at around 6 feet from the airframe, lifted from the ground.
 
On independant power (stand alone NiMH battery) and ESC disconnected. again airframe lifted from the ground. Twitching again started at exactly the same distance.
 
OK next the GWS Rx with 71 Xtal, no change to Corona results on either power supplier.
 
Finally the Futaba R136F with 71Xtal, reduced twitching on both power supplies, but still enough I wouldn't wqant to fly.
 
My other Futaba Rx won't work on Channel 71.
 
At each stage I have moved through all servos disconnecting one at a time with no improvement except one less fluttering surface!
 
I am happy to continue testing if we think it is needed folks, but will wait for a yes please or a no, and anyhting else worth looking at before i swap models to the ST330.
 
Thanks
 
Olly
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Yep, me too!
 
Anyone got any idea's before I look at stinging the credit card for a new radio system?
 
Although I may keep this Tx for use purely on the laptop for sims. The Rx's and crystals I'd probably sell on, I think they are OK and the flaw lies in the Tx.
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KC - Yep, GWS Rx's use Futaba crystals.
 
The battery is a Lipo Tx battery, and is running at around 11V at the moment.
 
I can try a different pair of crystals (I have chl 76 and 56 xtals).
 
KC - what do you reckon, try different xtals?
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Even though you mentioned you'd tried someone else's Tx, I too think that's where your problem lies, Olly.
 
Whilst what I know about electronics and radios could be written on the back of a fag packet, the symptoms are so similar to my Optic 6 problem that I suspect that there is a problem in the RF stage of the Tx.
 
It's a pity it's not a modular Tx as converting to 2.4Ghz would be relatively easy and cheap.....although if you're handy with a soldering iron, this hack module system only requires 3 joints and two holes drilled for a 6EX, according to the reviews.
 
Pete
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Olly
I just happen to have a Futaba 35 mhz Tx and Rx .Since acquiring my 2.4 Futaba stuff ( two lots of Txs & plenty of Rxs)
I've never used the combo .Batteries are NiMh .If you're interested ,give me a shout..Think of a price & let me know .It all works of course ! Not a lot of peeps want 35 Mhz these days which is why I've not advertised it .
Thinking of my Spitfire fund!
Myron
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The transmitter has a RF/ modulation fault.
Check the crystal holder’s soldered joints and associated PCB tracts.
A couple of years ago I was gifted a faulty 6EX that produced similar results.
The RF was not as modulating as expected when tested.
Couldn’t correct the fault.
 
It’s still under the bench gathering dust.
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One thing I haven't seen mentioned is how far apart all the components are. When I flew electric models on 35MHz I always used opto ESCs and standard NiMh receiver batteries, to prevent glitching. This was after I had problems eliminating glitching with my first model using the ESC's BEC for receiver power. Even then I had to place the receiver as far as possible -- up to 10" -- away from the ESC, motor, and motor battery. Obviously, it's not impossible to have glitch-free flying on 35MHz (my TwinStar was fine, using ESC's BEC for receiver power, and all components in close proximity), but sometimes you need to find the "sweet spot" for the receiver placement.
 
My radio gear was, and still is, Futaba. But I'm on 2.4GHz now and have replaced all my NiMh receiver packs with stand-alone BECs.
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First try to find the cause of the problem for everyones benefit.
If you consider leaving Futaba check what you get in other makes. Spektrum does not include Tx nicad or charger or switch harness if I remember correctly. You get all these in Futaba sets.
Of course you need the same make as your instructor if you use a buddy lead.

Edited By kc on 04/10/2011 13:08:33

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Indeed KC, I'll be looking for best deal for what I need, Tx Nicad wise I don't mind to much as I run a LiPo Tx batt anyway.
 
Regards Instructor Tx not a huge concern as club has plenty of buddy Tx's and cables to use as needed.
 
Looks like I'tll be a week or 2 before I order, but hopefully will get deposit I'm owed on a house back and that will more than cover a set for me
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Another consideration is interference on the servo side which 2.4 is not necessarily a cure for.
 
I had a problem recently on a 2.4 set-up when investigating why my throttle servo stopped working intermittently during taxying out for the previous attempt at flying (no apparent problems before this). I'm reasonably confident that the root cause was a loose fitting servo connector (it was anchored to a Y lead for an onboard glow with a keeper which kept it in place) which gave an intermittent contact but while fitting a replacement servo from my stocks (and trying several others) it became apparent that the combination of me, my transmitter/receiver/wiring/servos and possibly the location in my workshop was causing the servo to glitch and stop intermittently whenever I handled it.
 
Running the lead back to the receiver (a fair distance) with a couple of turns through a ferrite ring (increased to 5 once the cure was checked) stopped this happening but I did do some extensive range checks before flying it again.
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Having re-read the OP this probably doesn't explain the particular symptoms of 2 completely separate sets of equipment.
 
Logically, the only common link was Olly himself. I'd guess that given your occupation you don't use a pacemaker but perhaps we need to think along the lines of the old chestnut of mobile phones and the like? Even flying with too many shiny buttons maybe ?
 
Probably even more unlikely but between you and the other flyer on your frequency, there couldn't have been 2 transmitters on a common channel turned on at the same time at the field and then at home?
 
...or even adjacent frequencies?

Edited By Martin Harris on 04/10/2011 14:34:46

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Martin - nope, strict peg regime, and the other flier on 71 was sat having a brew with his tx still in the car while I was mucking about with it!
 
and at the field wasn't me doing the range checks, it was my instructor!
 
no shiney buttons on those clothes, no pacemaker, and my mobile was in the car, some distance away...and has not had this impact in the past.
 
In addition tried at home with a total of 4 different RX's and other servos completly out of airframes, so unless ALL my servos are stuffed then that one is out too i think..
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Hi Olly.....it seems you've tried everything....looking back through your posts I note that the borrowed Tx seemed to reduce the jittering & I assume that you were still using the ESC as a power supply...its a pity that you can't use this Tx & try out your equipment with a NiMh battery....I suspect this would work OK & would confirm that 35MHz & regulators can be problematic & that ultimately it is your Tx that is a bit dodgy!!!
 
Maybe the best option is indeed to replace the set & 2.4 is definitely the way to go.....what will you choose I wonder....
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Think I'm going for the Futaba 8FG, but want to feel one first.
 
As a final nail in the coffin of the old T6EXAP I have just tried a flight sim session with it. but the Tx was dropping out at random, and jumping all over the place, before I was even able to take off the SIM aircraft crashed. random throttle, random ail etc.
 
Anyone want some 35meg rx's I'm selling?
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