Model Boat Mayhem
Technical, Techniques, Hints, and Tips => Radio Equipment => Topic started by: colin-stevens on July 26, 2009, 09:39:16 am
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is it possible for a transmitter to lose range? ie, works perfectly at about up to 10ft, but anything beyond that, lose control ? i have checked and changed the tx battery.
found this to be the case on two seperate boats, same TX, different RX and frequencies.
colin
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Unlikely unless you've got a dodgy aerial connection. Could the problem be interference?
Barrie
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Sounds like interference.
Is it a full blown hobby grade Tx/rx like a Futaba.
Or is it one of these very cheap Chinese things with the ability to change crystals.
If the former, there could be some source of HF interference close by, like a mobile phone relay, or an airport landing control system.
I have even heard of a metal edge to a pond (on all four sides) being a possible cause.
If the latter, some of these sets have a very low power output and could be swamped/jammed by other hobby grade radios.
If it is a single freq 27mhz RC toy, then any radio will interfere with it and reduce your range to about 10 feet, I have done it to many people in the past.
Interference could also come from other 27mhz RC toys.
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it is a Futaba T6EXAP. pretty sure it it not intererance, same thing has happened on two different lakes. i have had a sugestion made by a freind that i may have damaged it by operating with the arial down for bench testing!! wondered if any one else had heard this?
colin
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i have had a sugestion made by a freind that i may have damaged it by operating with the arial down for bench testing!! wondered if any one else had heard this?
colin
That is supposed to be a risk, but I think only if you've left the tranny in that state for a long time. I've used my 6EXAP like that for short periods with no ill effects.
Barrie
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well, it does seem to be the common factor. cant think of anything else. just wondered if it had definatly happened to someone else and if there was a cure, apart from new set.
colin
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When you tried different boats, I assume you just switched the rx crystal.
If this is the case you are right it sounds like the Tx
If not, it could be the Rx Antenna.
The other link in the chain you only one thing left to be 100% certain it is the TX.
Change the Tx. I know it sounds silly, but it may show you something unexpected.
Another thing I have had, was something weird.
I tried every combination of every component change. And when I re-setup with all the original components the problem had gone. It may have been a problem with corrosion on the plug/connectors.
It is possible you have damaged/overheated a component (resistor I think), by leaving the antenna down, but unlikely.
You could also check that the Tx antenna is still firmly attached to its base in the Tx.
If you know somebody with a signal strength tester this can be used.
I think ACTion electronics do one. It attaches to your Tx Antenna.
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It may be possible to get your Tx serviced/repaired.
Perhaps another member in your part of the world knows who may be able to do this.
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It may be possible to get your Tx serviced/repaired.
Perhaps another member in your part of the world knows who may be able to do this.
Is there a Futabe service agent in London?
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Is there a Futabe service agent in London?
http://www.ripmax.com/Images/Handbook2003PDF/225_HB2003LR.pdf
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pretty sure its not a bad connection in the boats. checked the arial connection in the TX, seems ok, looking more like the TX. this fault harks back to a couple of posts i have made, one of them about brushless motors and supressing/ferrite rings.
will see if i can find someone with a signal meter, pretty good terms with my local model shop, see if he can help.
pretty sure that to get it serviced will cost more than a TX. sad, but it seems to be the times we live in. throw away culture, despite all the noise being made about recycling.
cheers guys
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Running any TX with incorrect loading changes the conditions around the output stage. Doing it for an extended period (How long is that? Depends.) could result in one or other of the components either overheating or being subjected to an excess voltage.
I seem to recall that the higher end Futaba TXs are/were available in differing frequency bands, the difference being the actual RF module. If this is the case, it might be possible to just get a new RF module.
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the output stage on some Hitec trannys would blow at one time if you used them for testing with the antenna down for any length of time.
Proteus,
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the output stage on some Hitec trannys would blow at one time if you used them for testing with the antenna down for any length of time.
Proteus,
That's interesting. Certainly my first reaction once I'd read that the TX had been run with the aerial collapsed was that the result was a cooked output stage. Changing the aerial length from a metre or so to a few inches drastically changes the matching to the output stage and, in layman's terms, causes the power to be reflected back into the output transistor instead of being radiated via the aerial. It may or may not kill the transistor, depending on the degree to which the transistor is overspecified to cope with this sort of overload or whether, as often happens in more powerful transmitters, there is a circuit which senses the problem and reduces the output power of the unit.
My other thought was whether you had dropped the TX as a sharp blow of that type could possibly have caused either a cracked PCB or a tuning component to be shaken away from its optimum setting.
HTH
Guy
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Looked in on this, it does rather sound like a cooked output stage as Malcolm and Guy have both pointed out. One should always avoid running a TX with the aerial retracted as the mismatch occurring in the output stage causes the output transistor to draw excessive current and get very hot.
Seen it many times, never do it!
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Ta,
never heard of it before, perhaps its in the destuctions. well hopefully i have learnt my lesson!!!!!!
now i can buy a new one with a degree of confidence it will cure my problems on the 2 problem vessels
colin