Crystals

[Foxfan]

kc,

I wouldn't use old NiCads, except for bench testing oddments. I can get 2300 NiMhs for £2-99 for 4 and would make up packs. I've done that in a bogus Ever Ready card wrapper downloaded from the net for my 56 year old Aerokits Sea Urchin, just to look right and they last for ages. Then they get charged in a wall charger. Same for my camera. So far so good.

You can't get period flat bell batteries any more! I make a styrene box up and put the brass tags on the end. Goes well with the equally ancient toggle switch. No radio in that one! All restored last year. I was given it as a 7 year old.

My 1971 Mini-Hex proportional 27 meg used DEACs, but they've had to be discarded for NiMhs too. But they go in the original red plastic DEAC case.

This is all very cheap to do and effective. Obviously for any more expensive solutions I would indeed spend it on 2.4. I have an Orange RX to go with the Spectrum DX5e Tx, which has not yet been taken from its box! I was astonished at how inexpensive the Orange RX was. I also bought an in-aircraft mixer for elevons and only afterward realised the DX5e has a built in mixer! Yes, I am a closet flying wing fan.

Mike, thanks for your explanation of the operations of 35 meg Rxs. Along with others above, I am now getting a bit of a handle on how they work. I'm glad I am likely to be the only 35 Meg user at the field!

Cheers,

MrTin

[Shaunie]

Sorry Phil had a brain fade, don't know where I got the 1.6MHz first IF from but in my defence I did say from memory!

I was trying not to be too technical hence my statement about not using crystals from a different make, if the crystal spec is wrong and is fitted in a Tx where the load capacitance is incorrect for it then surely it will be transmitting off channel, not by much admittedly but nevertheless wrong.

465KHz IF? Thought that was going out of fashion when Noah was building his technology demonstrator!

Shaunie.

[Foxfan]

Well, chaps, what a strange day. I got my crystals...a set of three al the same in Hitech labelled bags and a single one, also claimed to be Hitech from another supplier.

Put the right one in the Code 4 Rx and a Tx one in the e-flight Tx. Nothing happened.

So, put my friend's No 72s in the same gear and nothing happened. Then put one of mine in his Futaba Rx, one in my E-flight Tx, and the servos all did weird things, like two doing exactly the same together, while one twitched and his Futaba servo doing what it should.

Tried my crystals in his Futaba TX and Rx. Nothing.

His crystals in his gear, servos worked fine.

So, what's going on here? Could it be that the unused Code 4 Rx is duff, that my E-flight Tx s partly duff or the crystals are duff?

Should I get a s/h Futaba Rx off the 'bay and try my crystals in one of my Futaba Txs?

Surely crystals don't usually go duff?

Or give up and go totally 2.4.

Or get hack modules for the 35 meg Txs I have and buy Orange Rxs for any model I build. Seems a shame not to use the Futaba Txs. The e-flight Tx was only 99p!

Any thoughts?

Cheers,

Martin

[GONZO]

A few pictures of all the parts would help a lot.

[John Privett]

Martin - what make is your friend's gear? You said you tried his 72s in your gear, but you also mentioned your friend having a Futaba Rx. Is all his gear Futaba?

The guideline to stick to is to put a Brand 'X' crystal into Brand 'X' equipment, Brand 'Y' into Brand 'Y' etc. etc. Other combinations might work, but more than likely won't!

So putting a Futaba tx crystal into a different brand tx might;

• Not work at all
• Work, but on a different frequency in the 35MHz band
• Possibly even work, but on a frequency outside the legal 35MHz band.

Similarly, putting a Futaba crystal into a non-Futaba crystal might;

• Not work at all
• Work, but on a different frequency in the 35MHz band
• Possibly even work, but on a frequency outside the legal 35MHz band.

If it's a dual-conversion crystal and an 'ordinary' rx then the rx won't work at all, and vice versa.

So, putting 'alien' 72 crystals into your gear might result in the tx transmitting on channel 73 and the receiver 'listening' on channel 71. Or something like that...

You need to use the right crystals.

Some years ago a beginner at our club had some peculiar gear - GWS if I remember correctly. I managed to obtain a buddy lead that would work between his GWS tx and my Futaba tx. But we had to buy a Futaba tx crystal on his frequency to put in my Futaba tx. I did try his GWS tx crystal in my tx, but it gave a very poor signal. Listening on a scanner it was transmitting between the wanted channel and the next one - actually giving a stronger signal on the 'other' channel.

[Phil Green]

You can verify that the transmitter is actually transmitting by putting the aerial close to a domestic FM receiver tuned to the third harmonic which for channel 72 is 35.12 x 3 = 105.36mhz

Another variable is shift. Some FM transmitters shift frequency up during each PPM pulse, some shift down.
Some receivers will work with either shift (eg Corona) and some have to have the right shift. Futaba and Hitec have the same shift but I dont know about E-flight, maybe its the opposite shift to what your receiver is expecting.

I thought I'd read that you'd bought a Futaba transmitter, maybe I misunderstood

Cheers
Phil

PS I think you should get some flying in with that DX5e and Orange receiver   

 

Edited By Phil Green on 14/08/2015 00:40:27

[Foxfan]

I bought the Tx (e-flight) because it said it was a Hitec clone, like the Code 4 Rx and servos. So I bought Hitec crystals as I was told Hitec crystals were different from most.

My friend's gear is all Futabe which he's had for years and all of it has always been Channel 72. The crystals I bought were Channel 90 because that was the channel the two suppliers (of Rx and Tx crystals) had the same.

Phil, I did buy a Futaba Tx recently, because, well, it was there and cheap and I didn't want to douse any interest from my Mrs., who spotted it. That's the T6EXA.

Reading more about using hack modules and I think I might go that way, you're right about the DX5e/Orange, I reckon!

Cheers,

MrTin

[John Privett]

Shift - that brings back memories, Phil! Mostly discussed by Americans in the past, as with their 72MHz gear some brands shifted 'up' and some 'down'.

For some reason it seemed only to be an issue on 72MHz, and gear on other frequencies in the rest of the world - 27MHz, 35MHz, etc... all used the same shift direction. It is of course entirely possible that E-flight have gone against the norm and shift in the "wrong" direction on 35MHz.

Skimming back through the thread you're right Phil - Martin did mention that he had 2 Futaba txs. I'd suggest he puts a Futaba tx crystal in one of the Futaba txs, then tries whatever rxs he has. Each rx will need to be tried with a crystal of the same brand as the rx and on the same frequency as the tx. And Futaba 35MHz rxs should be available s/hand for next-to-nothing if one needs to be bought. Otherwise go to 2.4!

[Foxfan]

John,

I think I'll be going 2.4, with FrSky modules in the Futaba Txs. The e-flight TX, perhaps, should be written off. It was all of 99p!. And, with my DX5e, the Futabas will be more than enough for me.

Cheers,all,

MrTin

[Phil Green]

I'm not a Spektrum fan but....
The DX5e is disregarded by many as a 'toy' set but its a very capable transmitter. It has 6 channels, not 5, it has expo, dual rates, reversing, a mixer, has the same full-power RF module as the higher models. So it has more facilities than we ever had on the Skyleaders and Digifleets we all flew quite happily!

I think your priority should be to get some flying in with the DX5e, get some enjoyment from your investment, and sort out this 35mhz conundrum later!

Cheers
Phil

PS Eflite as a Hitec clone is a new one on me, wasnt aware of that. Isnt Eflite Horizon Hobbies, ie a Hitec competitor? I dunno.

[Foxfan]

Thanks, Dave,

I think you're bang on there with your sage advice to get at least something airworthy, which, at current progress on the Super 60, will be the Ugly Stik I was given, which just needs a 3S Lipo and one of the brushless motors I have.

I assume the DX5e is regarded as a toy, because it isn't programmable, but it was affordable at the time and does anything I'm likely to need or understand!  My old chum with his non programmable Futabas could probably fly rings round most of the club's program flyers!

The "35Meg Conundrum" can indeed be played with later.

I can't recall exactly now, but assume I would have taken what the ebay ad. stated or I wouldn't have bought an e-flight TX., but a crap memory leaves me clueless at this remove and 99p poorer.

It appears to have been for a helicopter, since it has a gyro switch and knobs for pitch trim, etc. (Cue emoticon for a Gallic shrug).

So, now, I need to learn about binding.

But many thanks for all your help.

Cheers,

MrTin

Edited By Foxfan on 14/08/2015 17:14:16

[kc]

I think we may have convinced you not to spend any more money on 35MHZ! But try to get a refund on the crystals which seem to be unusable.

Regarding the Ugly Stik - is this a full size about 60 inch model? If so is a 3S going to be any good? A smaller version like the 48 inch Das Liddle Stik might be OK on 3S but surely not the 60 inch.

Assuming the Ugly Stik weighs 5 or 6 pounds then you are going to need 500 or 600 watts to get decent performance. ( some might say you need more ) So with 3s ( 11.1 volts ) then it will need an expensive ESC that can safely handle the current. A 60 amp ESC would not really have enough margin for safety. Bigger ESC are a lot more expensive.

4S might be better ( some might say you need 5S )

[Foxfan]

kc,

I'll try for a refund on the crystals. If successful, it'll buy me another Orange Rx.!

The Ugly Stik, if that's what it is, is only about 33" span. Ready made and originally with a geared 400 brushed motor, but the gearbox shaft bent, so out it came, then my friend said, "here, you have it, I hate the look of it".

I weighed everything and it comes to 500 grams, within the abilities of my imax 2028 motor, according to specs. I have a 25 Amp ESC which came with the motor, but may play safe and go for a 30 or even 40. The motor says 11.1Volt on it, hence 3S. I'm open to views obviously, as I know nuttn' about these electrics. I haven't yet got the B6 charger to work! On anything.

On the principle that it's sitting there just needing innards, I figured it could be a good candidate for a first flight.

I also have a pair of plastic trainers, one a 35 Meg, one 27Meg! I suppose I should be a good boy and remove the 27 Meg "brick" and put lightweight Rx and servos in it. That's a Commander V tail. The other is a Ripmax Reflection, both brushed motors. I really don't like the cotton reel/elastic band servos and limited control movement though. But they were a birthday present from my son, so I ought to persevere with at least one of them.

Then there's the enlarged Snazzle sloper and the Skystreak 32, which I'll save for when I can actually fly a bit! The Skystreak will also be electric as I have no small glow engines.

Cheers,

MrTin