Lost radio contact

[Frank Skilbeck]

Just a note, I have an early Dx6i (still working OK) and it is designed to run on 4 AA cells, typically 5.5v when fully charged, if you put in a 2s Lipo/Life with 8.4/7.2v respectively could this burn out any internal regulator as it drops the voltage?

I know the later Spektrum transmitters were designed to run on Nimh/Life/Lipo options but I am not sure the Dx6i was.

[Paul Marsh]

Posted by GrahamWh on 09/04/2019 20:47:00:

I can get a 700mAh LiFe battery that would fit inside the battery box - would that be sufficient capacity do you think? It would avoid the need for the wire outside the case to the existing LiFe battery. A new TX is not an option financially at the moment. As mentioned earlier, I will get the aerial fixed in a better way.

You can get a new DX6 for less than £100. Why risk causing an accident and possible injury if it happens. Not saying to blow all your money, but if funds are tight, put it on a credit card and pay an amount off each month. Interest on that won't be much and knowing you have a more reliable unit.

Seriously, if I saw your tx at a fly-in and was a marshal, as I am at the Nationals Evening 2.4 line , I would probably ask you not too fly. Not being horrible, but in these times, safety has to take 1st place, and if you cannot afford to fly safe, i'd suggest in not flying at all for now...

[Martin Harris - Moderator]

Playing Devil's Advocate, which would be worse - a soldered external battery (it does look better with the cover on) or dry batteries conforming to the maker's spec but with many examples of experienced modellers stating that they consider them dangerous?

Better to simply ban all dry battery equipped transmitters from public events?

[GrahamWh]

I must admit I think my Tx is now safer than a new set with dry cells and those contacts. The aerial will be done with fibreglass which will be fine, 

Does anyone have any idea if 700mAh would be sufficient for a battery - if so I could put one inside the battery box where the dry cells originally fitted rather than have this larger one fitted outside?

 

Edited By GrahamWh on 10/04/2019 06:54:29

[Denis Watkins]

Graham, everyone is reluctant to give advice on the 700mah pack, that then you will continue with the duff aerial and dodgy set up.

A 700mah pack will keep its charge for months in a Tx with normal use, Always remove to charge.

As always, monitor your volts in the Tx panel, and check with your meter routinely as the drop off volts are rapid at the end of the last charge, but will last weeks, not just days

Believe what you will about dry cells, but dry cells discharge gradually, are more robust internals than a rechargeable, and hold voltage higher and longer than a rechargeable pack. A whole Manufacturer has designed and made a unit confident in their use

[Former Member]

[This posting has been removed]

[Lima Hotel Foxtrot]

Posted by David Ashby - Moderator on 09/04/2019 09:47:59:

Is that sellotape holding your Tx aerial together Graham?

Exposed wires, sellotape fixes? I've got to be honest, it's not a Tx that inspires confidence.

Although, technically, the sellotape is not actually holding the aerial together; it's holding the plastic case that the aerial sits in together. The aerial is untouched and should be broadcasting as normal as it sits inside the case. Although not if it's been damaged by whatever event broke the plastic bit.

[Nigel R]

Not sure if this has been mentioned yet, but I think replacing the RX and satellite is an overreaction.

[Peter Miller]

Talking of repairing aerials. My Spectrum DX7 aerial broke, just the plastic part. I repaired it with Polymorph. A thermosetting plastic that can be moulded after soaking in hot water. It has been like that for at east a couple of years and has never gven any trouble at all. Much stronger than the original flimsy floppy joint which could possibly cause fatigue of the actual aerial due to constant movement between the two parts at the hinge.

Polymorph is quite cheap and available on EBay.

[Former Member]

[This posting has been removed]

[GrahamWh]

Thanks again gentlemen.

I will think more about a new Tx Paul. I guess the pots do also wear out after some years and maybe a new one would be a good idea soon-ish.

Thanks Peter for the info re Polymorph. I'll fibreglassing the aerial this time as that's the material I have ready to hand. Even before it broke, the supplied aerial was not very good - it was too floppy and would flop to the horizontal position so it pointed at the model after a couple of year's use degrading the signal pattern the Rx would have received. Some tape even at that stage would have been an improvement, but something more long lasting like polymorph or fibreglass would be more reliable.

Thanks for the reassurance re the 700 mAh packs Denis and Andrew.

While I wait for a battery I can get into the battery box I'll put a bit of duct tape over the wire on the back of the Tx from the existing external battery to the battery box to eliminate any chance of it catching something.

I have noticed on friend's Dx6is that some have had to put a bit of tape onto the battery box cover to stop it falling off as they seem to get loose. I expect that could lead to the dry cells simply falling out if the Tx is knocked in use.

Nigel I think I will delay chucking the Rx and keep it for a lightweight electric model that will not be able to fly the distance to our boundary fence if the signal is lost to test it over time, thank you.

Edited By GrahamWh on 10/04/2019 17:48:55

[Stephen Smith 14]

Aerials falling apart, battery box covers coming lose, poor connections, pots wearing out, and that's without the endless reports of loss of range. Why O why do people continue to buy this cheap and nasty rubbish?

[Alan Gorham_]

Because it is cheap?

[Former Member]

[This posting has been removed]

[Nigel R]

Has the thread got to that point already?

[Paul C.]

I am amazed that it took as long as it did 😨 �😨😨😨😨

[Peter Miller]

I was told that the aerial on these sets is actually designed for use on Routers. Those are not usually carried around, dropped and used out on the field.

I would just mention, as I have before, I had one of the first Spektrum DX 7 outfits in the country. I have never had any problems with it in about 10 years and some of my models have been flown at considerable distance from the transmitter.

[gangster]

I cringe when I see people fiddling with their aerial orientation every time they fly. There are all sorts of old wives tales re aerial orientation but it ain’t that simple all sorts of other factors come into play, and believe it or not the model moves in three dimensions all the time. If you are a compulsive twig twiddles at least but a new one every year. As for repair how about a bit of black heatshrink it would look a whole lot more confidence inspiring than sticky tape

[Martin Harris - Moderator]

Although the model moves in all orientations, there is sometimes a tendency for pilots to point the transmitter in the direction of the model. In this case, a non "straight up" aerial orientation does give a better signal radiation pattern as end on is the worst case. It's certainly time that all manufacturers should do away with vulnerable external aerials!

I do find the sellotape arguments amusing though - while it might look untidy, it has absolutely no detrimental affect on the function of the aerial.

[Former Member]

[This posting has been removed]

[David Ashby - Moderator]

I think comments were well-intended but we'll stop it here. Hope it goes well Graham.

[Wilco Wingco]

DX-7 outputs eight (not seven) channels at the DSC interface

 

What does this mean???.?

[Phil Green]

Your end-to-end system relies on dozens of spring-pressure contacts.
Six per servo (pos, neg, ppm on the connector, pot wiper, motor brushes)
Four in the stick units  (two pot wipers each)
Eight trim push switches
Two in the rx slide switch, two in the tx slide switch
Two on the tx aerial, one per rx aerial
Two in the tx battery connector, four in the rx battery connectors
Five more if its a module radio...

These are all sprung contacts and I count 55 in a 4-servo model.

It seems we do trust sprung contacts after all !

Cheers
Phil