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Jan 07, 2020, 07:13 PM
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JR DSMX receiver compatability


Can I assume that SPEKTRUM DSMX receivers will be compatible with my JR X9503 2.4 DMSX Tx?
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Jan 08, 2020, 02:12 AM
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Zeeb's Avatar
Yes, those tx's have the Spektrum RF deck. You can run DSM2 or DSMX rx's.
Jan 08, 2020, 03:41 AM
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Thanks Zeeb. And this may be a silly question, but some of these rxs have a 'satellite' module, and both the main receiver and the satellite each have 2 tiny aerials. I fly small electrics and with little fuselage space for 'extra' receivers, would I be safe using any DSM2 or DSMX receiver having longer aerials and without the satellite receiver?
Jan 08, 2020, 03:47 AM
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Zeeb's Avatar
Quote:
Originally Posted by joolstacho
Thanks Zeeb. And this may be a silly question, but some of these rxs have a 'satellite' module, and both the main receiver and the satellite each have 2 tiny aerials. I fly small electrics and with little fuselage space for 'extra' receivers, would I be safe using any DSM2 or DSMX receiver having longer aerials and without the satellite receiver?
There are various "Park Flyer" rx's available which do not require a satellite rx. If you use an rx that comes with a satellite, then you must use a satellite. This is true of all the Spektrum RF based stuff be it JR or Spektrum. IF a satellite is involved, It MUST be the same format as the main unit e.g. if the main unit is DSM2, then the satellite must be DSM2. Likewise if the main unit is DSMX, the satellite must be DSMX.
Jan 08, 2020, 03:57 AM
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Thread OP
Good advice, thanks. Makes sense to keep main rx and satellite on same format obviously.
My aircraft are not park fliers, (Around 1m to 1.4 m spans).
They're high performance aerobatic things and I need good range.
Jan 08, 2020, 10:38 AM
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richard hanson's Avatar
Some may say no but I would buy a 620 rx, the one with internal a ntenna and put into one of your smaller , all foam aerobatic models
These new rx have excellent range
The possible problem is in having the rx blanked by carbon fiber or metal
This is why the two rx setupisused on larger models
The diverse placement of the antenna reduce possibility of a blanked signal
They do not increase range
They decrease possibility of blocked signal
IFyou do good comparative long range tests you will see what I mean.
Jan 08, 2020, 12:24 PM
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DGrant's Avatar
Also to add to what Zeeb shared, if you install or switch out a "satellite"(or "remote Rx" as it's also called), you need to rebind the system so it recognizes the new satellite component.

A new satellite Rx won't connect with main and system until you do a rebind, and the indicator light is solid red.
Jan 08, 2020, 05:38 PM
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Thanks for the advice fellers. I'm aware of the carbon issue, I only use it sparingly in my fuz mouldings, and just down the tail end. I will do range tests for sure. What's the verdict regarding lipo batteries masking the signal, is that an issue?
Jan 08, 2020, 07:29 PM
65 years of RC flying
Daedalus66's Avatar
Quote:
Originally Posted by joolstacho
Good advice, thanks. Makes sense to keep main rx and satellite on same format obviously.
My aircraft are not park fliers, (Around 1m to 1.4 m spans).
They're high performance aerobatic things and I need good range.
Not just “makes sense”, it’s mandatory. They don’t work otherwise.
Jan 08, 2020, 07:43 PM
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DGrant's Avatar
Quote:
Originally Posted by joolstacho
Thanks for the advice fellers. I'm aware of the carbon issue, I only use it sparingly in my fuz mouldings, and just down the tail end. I will do range tests for sure. What's the verdict regarding lipo batteries masking the signal, is that an issue?
I would stay well clear of anything dense like that with the remote rx's... or anything electronic or any dense material. We know signals pass through most woods and fiberglass, but most of that isn't dense, or solid. Carbon fiber is probably the most dense of all material we use, in which case it doesn't take much if anything to shield a signal... but you know that. I think batteries are about the same as c/f, as they can be very dense, as well as wrapped in their own shielding(IE;metallic wrap) for various reasons, which in turn will shield anything it's in line with.

It's best to place the remote Rx's, and do a range check, and see what the telemetry tells you. That will tell a story, and what if anything that might need to shift around. If your ground range checks out, maybe do a close-in flight and see what telemetry report says, and what the signal performance is doing.
Jan 08, 2020, 07:50 PM
65 years of RC flying
Daedalus66's Avatar
Quote:
Originally Posted by joolstacho
Thanks for the advice fellers. I'm aware of the carbon issue, I only use it sparingly in my fuz mouldings, and just down the tail end. I will do range tests for sure. What's the verdict regarding lipo batteries masking the signal, is that an issue?
Yes, any battery (or other conductive object) can mask the signal.

What you need to do is a thorough reduced power range test from all directions to make sure there aren’t any blind spots in the signal reception. Set the model on a wooden table or other non-conductive support at least 50 cm (18”) high. Move to a position 30m away and put the TX into range check mode (hold the module button). Walk 360° around the model, maintaining the distance while moving a control to check the connection. If you get any loss of control, you need to change the setup.

You might also do a further test with an assistant standing the model on its nose on the table and rotating it while you move the sticks.

Once you are satisfied that there are no dead zones, a simple 30m reduced power test should be performed at the start of each flying session to make sure things are working properly.

A reduced power range test result of 30m corresponds to 30x range at full power, that is, at least 900m. Most DSM2 and DSMX receivers can easily meet this standard if the installation is properly set up, and recent DSMX receivers can exceed it by a wide margin. But a bad installation can cause intermittent signal loss at normal visual flight distances, so rigorous testing is well worth while.
Jan 08, 2020, 08:26 PM
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Thread OP
Never had these problems with FM... even AM !
Just kidding - I like the irony though, we assume that new technologies are always good, but often there's a downside too! THX again for the advice, I'll do the tests before chucking!
(I do love my JR 9503 TX though, it's such a sweet piece of equipment).
Jan 08, 2020, 09:22 PM
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DGrant's Avatar
Quote:
Originally Posted by joolstacho
Never had these problems with FM... even AM !
Just kidding - I like the irony though, we assume that new technologies are always good, but often there's a downside too! THX again for the advice, I'll do the tests before chucking!
(I do love my JR 9503 TX though, it's such a sweet piece of equipment).
Oh... we had these problems, many of us just didn't know it like we do today.

These days any signs of trouble are usually taken care of well before a mishap. Just keep studying.
Jan 08, 2020, 09:38 PM
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Thread OP
I flew for maybe 30 years without issues on old tech, as long as sensible care was taken with plugging, battery etc, plus of course careful (easy) frequency checking on site.
I still have my beaut ol' FM Futaba FF7 which still does a great job, just that my 'new' JR 3503x is too sexy not to use!

"we had these problems, many of us just didn't know it like we do today".

As part of my "keep studying" I'd like some elaboration of the above statement. Any chance?
As I said, with AM and FM, obviously the main thing was careful checking of frequencies at the fly site. Pretty easy. As I said, 30 years and no frequency conflicts for me, (even at uncontrolled slope sites where frequency boards were not in use).
And the other things like security and quality of plugging, wiring etc, is the same with 2.4g systems too so no diff.
Wondering what we "didn't know" back then and what "we do today"?

Yes I'm aware of the 2.4g advantages - less response lags, reliability? (moot point). Big disadvantage seems to me those tiny short 2.4g aerials make it much harder in installations to avoid masking of the aerials, with AM & FM we had those lovely long aerial wires that could always be routed clear of any masking.
Last edited by joolstacho; Jan 08, 2020 at 10:21 PM. Reason: Addition
Jan 08, 2020, 10:06 PM
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DGrant's Avatar
Once you start coming to know many of the advanced features a modern radio has, most people really move up and away from our older radios.

I still have 3 of the Futaba FG-7 Gold Box radios, all still work of course. As well as the newer 8UAS and 9CAP, all still work of course. No issues whatsoever. They're in my history box, as well as a few of them still operate planes... and do a great job.

When I stepped into a telemetry system it was a real eye opener, because with that kind of system we really can get a good grasp on how everything is performing.

In our earlier years of RC everything worked, but that's all we knew. The battery has a charge, then go fly. The control surfaces move, then go fly. As we've evolved though, and the cost of our models and equipment goes up, I want to know as much as I can about how things are working... onboard telemetry is the ticket.

If you really want to know if your remote receivers are operating optimally telemetry is the way to go. Just sayin'. I've seen old tech, and I've seen new tech... old tech is cool, new tech is new. Good luck with your system. I think you'll do fine.


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