Radio Question

[junglelord]

I was given a free digital tx. Its 72MHz. Futuba PCM1024 Super, 7 channel digital tx that was for a helicoper.



I am told that the tx can have the crystal changed to a 75MHz.
I need a SL-8 and a ADF.
Will this tx work compatible with the above and is that correct I can swap out the 72 for a 75.

Thanks

[Kazzer]

I just sent mine in to be changed over. I cost me about $50 including the postage. Look up the Futaba web page for the form and shipping instructions.

[junglelord]

Oh! I thought I could just plug in a new module. I thought it was this external crystal plug on the back.

[He Who Shall Not Be Named]

Oh! I thought I could just plug in a new module. I thought it was this external crystal plug on the back.

With your type transmitter, yes, it's a simple module swap -- but don't think you can make a band change with just a crystal; the entire RF side of the transmitter circuit has to be tuned for the 75mHz band, not just the crystal. So, you get a 75mHz module for that transmitter, you'll have a good system and, more importantly, you'll be street legal on this continent.

David,

[junglelord]

Cool, thats what I thought. I hope they are not too expensive.
Have to phone the hobby store in Ottawa tomorrow.

[toppack]

I swapped crystals, in modules of 2 similar Futaba transmitters, from 72 to 75 band, and they work.
I've never done a range test on those, but no problems at less than 100'.
I never tried to tune them since I mainly use them for backups and bench testing other equipment.
The modules, in these I have, have a small removable stick-on cover on side of them but I pulled cover off module for better access to crystal. Crystal is in socket, not soldered in.

[Slats]

I know this is a question on Frequency 72 to 75 mhz and I hate to throw a spanner in the works but that's a PCM unit right?

Some PCM units with their on board programable fail safes do not play well with RC sub fail safes and ESCs that have on board fail safes too.

If you can turn off the fail safe functions on the TX, do so, and you will have a better time of it. You might get lucky and find this particular unit does not have an issue, but just about all the Sub guys in my neck of the woods (Australia) run FM / PPM because of bad experiences with some PCM units being not compatible with our ESCs and MPD / fail safes. Sure we run different Freqs down here but the PCM / PPM issue is real no matter what Mhz we are talking about.

John

[KevinMc]

That's a good point John. Fortunately, the radio in question is programmable for both PPM and PCM operation so there's no issue on this point. (I know, I have one.)

The failsafe "feature" you talk about is however as much a question of something offered by the RECEIVER as it is of the transmission protocol. The SL8 which was mentioned is a PPM receiver but has a fully capable failsafe built in. (And as you noted this must to be left in a deactivated state to make all our gizmos work right!)

JL- You definitely should call ahead about the transmitter module. They're hard enough to find as a stocked item on 72MHz, a 75MHz module will almost certainly be a special order. (I think I had to wait a month for my 75MHz Spectra module to come in.) In the mean-time, you can test out and setup your SL8 and ADF just fine on the 72MHz module you have.
I'll drink to THAT!

[junglelord]

You guys are AWSOME!
I will be going to Ottawa this Saturday, so I will place my order then, if they have none in house, which as you say, is most likely. If they have it in house, I hope to have enough to buy one.
Any idea about how much they average in price?

[Slats]

You guys are AWSOME!

yes well the forum is awesome.I'll drink to THAT!

I am primarily here to learn. I'll drink to THAT!

Lets all do our best to keep the signal to noise ratio high.

J

[junglelord]

You mean signal to noise ratio LOW....
;)

[He Who Shall Not Be Named]

You mean signal to noise ratio LOW....
;)

Nope, he wants MORE signal, LESS noise. It all depends on what element is to the right/left of the /.

David,

[junglelord]

In electronics that statement, means more signal, less noise.
;)

Is this compatible with my transmitter?

http://www.robotmarketplace.com/products/0-HP-PLL75.html

Compatible with any Futaba or Hitec transmitter that uses the plug-in style rear modules (except the 72Mhz 9Z)

It appears to be the proper plug in unit.
I believe I do not have a 9Z from what I can tell.
Allows me both PPM or PCM.
Thanks in advance.

[toppack]

I've not tried one of those Modules but I've read that they work well. (written by an unbiased reporter, I think)
It would be handy to have if you have several models on different frequencies and go to a pond where other guys may be using one or more of your frequencies.
Otherwise I don't think it would be worth the expense.
I had that problem at our RC club meetings, and was the reason I built the custom transmitter, with 4 switch selectable frequencies. Of course no one made those modules then. :( In fact I don't think anyone even made module type transmitters then. :D

[KevinMc]

Yes, that's the module you want. Snag it now while you can. (I didn't know they were discontinuing them, although I can't say I'm surprised.) And I beg to differ about the compatability with the 9z - I've been using just that combination for 3 years now...