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 DSM2/DSMX vs. 72 MHz in ESL
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lincoln

49 Posts

Posted - 04/02/2011 :  3:53:54 PM  Show Profile
Hi,

My Vision radios, ancient as they are, don't seem to be working right any more. I've almost accidentally acquired a pair of JR 8103a's. I have a DSM2 module and AR7000 receiver, I also have a couple of 72MHz modules that will fit. I have a number of 72MHz receivers, some are Hitec or FMA dual conversion, a couple are JR. The JR ones make me nervous, to tell you the truth. I understand that the 8103a can be made to do reverse differential with CROW, and I guess it's otherwise adequate, though I haven't tackled the programming yet.

What's been people's experience with DSM2 in the ESL? I know I've seen a couple of problems locally but that was a while ago, and I don't really know if there was really a problem because of the kind of radio equipment or not.

If you're using DSM2 with a 3M glider (not a red one, though), is it necessary to use a 5 cell pack instead of a 4 cell pack? I probably will use 72MHz when flying DLG, but that's not certain.

Not sure which way to go this year. I saw some promotion for DSMX that made me wonder whether the DSMX was the latest whiz bang or was fixing a nasty problem. They say it works better in a "saturated" environment, but I don't know if that means an ESL contest or not!

Thanks!

Lincoln

Lincoln Ross

soarkraut

24 Posts

Posted - 04/05/2011 :  07:05:35 AM  Show Profile
Lincoln
Be aware that the older 8103 has an internal battery. It is soldered to the board and not easy to replace.I made a doorstop out of an 8103, some years back, following directions to replace a worn out battery.
I think it just provides power to the memory chip, when you remove the main battery.
Was a pretty nice radio, other than that.
Pete
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lincoln

49 Posts

Posted - 04/07/2011 :  10:30:24 PM  Show Profile
Thanks. Maybe if I screw up, LISF will revive the transmitter toss event. (It was them, wasn't it?)

Lincoln Ross
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lincoln

49 Posts

Posted - 06/11/2011 :  5:51:57 PM  Show Profile
I've tried the alleged reverse differential, can't seem to make it work right. Probably going to give up on these or use for dlg only.

Lincoln Ross

Edited by - lincoln on 06/11/2011 5:54:09 PM
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lincoln

49 Posts

Posted - 04/15/2012 :  6:49:35 PM  Show Profile
Any further opinions on this topic? I have now had 3 or 4 radio problems on 2.4. That's more than I had in MANY years with 72mHz. Is this coincidence or is there really a problem with the format? Or do I just have to get the latest whiz bang, FHSS3 or DHX or whatever?

Two or three problems at medium to long range with a Radian, one of these with aftermarket receiver. Today, first problem with Airtronics RDS8000 and rx that comes with it. A bit on the low side, medium range. (600 feet??800 feet?). Battery was ok, too.

Lincoln Ross
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aeajr

475 Posts

Posted - 04/15/2012 :  10:10:52 PM  Show Profile
Not sure what your question is Lincoln. I have been flying a Radian for 2 years using he stock AR500 receiver and DX5e with out the slightest issue. And, as you would expect, I fly it high and I fly it far.

Aftermarket receiver???? What aftermarket receiver are you flying?

I know quite a few people fly JR DSM2 systems in the ESL. Can't say who has had a problem and who has not. Correct installation is critical and, in some ways, more critical than 72 MHz because of the very short antenna of the 2.4 GHz systems.

If you have carbon in the fuse fabric you will likely need to route the antenna outside the fuse. Of course this is often true on 72 MHz. When my supra and AVA were on 72 MHz I taped the antenna to the tail as I occasionally had glitches on Futaba and Hitec receivers. They are both on Futaba FASST 2.4 GHz now.

When I took the Supra to 2.4 I did upgrade the Supra to 5 cell. The AVA is still on 4 cell but the AVA places less load on the battery.

I have a new Supra Pro being prepared. That will have 5 cell and Futaba FASST. And my Graphite will also go to Futaba FASST and will get 5 cell. The 5 cell just gives you a little more voltage margin, in my opinion.

I have several planes on Spektrum but they are shorter range planes like the BnF planes. No problems. I have not worked with Spektrum DSM2 or Airtroncis in carbon fuselages. The Futaba FASST has had zero issues with the carbon/Kevlar weave of the Supra and the AVA. I have all antenna internal.

Be sure to range check your intial installation from ALL angles. I put mine on a stand and did a 360 degree range check, then I had someone hold the plane so the bottom faced me and then the top to insure I had no blind spots. It is MUCH easier to get a blind spot on 2.4 than on 72 due to the very short antenna.

Don't know what else to offer. World class competition pilots have flown DSM2 at international championships. The ONLY place I would be concerned about DSM2 would be at one of these events where they have over 100 pilots on 2.4 GHz with no frequency control. There is nothing magic about the 100 number, just a reference point that I would consider. As more and more pilots move to 2.4, the RF spectrum gets more crowded and the frequency hopping systems seem to withstand this better than the 2 channel DSM2. BUT, for a typical ESL contest of 50 pilots or less, I would not be concerned.

BTW, did you see the article in the ESL Newsletter about upgrading from 72 to 2.4?


Best regards,
Ed Anderson
Long Island Silent Flyers
ESL Newsletter Editor
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aeajr

475 Posts

Posted - 04/15/2012 :  10:41:27 PM  Show Profile
Here is the April ESL Newsletter with the article on upgrading from 72 to 2.4. You might find it interesting.

Best regards,
Ed Anderson
Long Island Silent Flyers
ESL Newsletter Editor
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