IOMICA Forum

Sepktrum RC (www.spektrumrc.com) seems to be a really nice development of radio control technology. This was discussed here before but I was reminded of it in a recent article in MMI.
Information about which stick-radios are compatible with the system seems to be hard to come by...

In the MMI article the Futaba 3VC and Hitec Pro-Car are mentioned. On the other hand the spektrumrc website FAQ says something negative about the Pro-Car....

could anyone confirm or deny that the spektrum system(model SPM1004: Futaba/HRC) works with the Futaba 3VC ??

Anders

Anders
I have had the system in my 3VC for nearly a month. It has worked fine at short range, up to 600ft but I was waiting to do some long range testing before posting on the forum. There have been some negative coments about this. The system drops in nicely and is very simple to set up. The rx is very light, but there have been problems when they are used with some RMG winches. I use the Hitec arm winch with no problem.
I'll let you know how I get on with the long range tests.

Hi Anders, there's a longer discussion on the USA site.

http://onemetre.sbmyc.com/forums/viewtopic.php?t=103

Rob Guyatt has addressed the compatability problems, see
http://www.users.bigpond.com/rmgsw/Upgrade0405.htm

Regards

Ken

Nigel28 wrote: I have had the system in my 3VC for nearly a month. It has worked fine at short range, up to 600ft but I was waiting to do some long range testing before posting on the forum. There have been some negative coments about this. The system drops in nicely and is very simple to set up. The rx is very light, but there have been problems when they are used with some RMG winches. I use the Hitec arm winch with no problem.
I'll let you know how I get on with the long range tests.

great news ! I'll have to order the system real soon...

How do you run the antenna from the receiver ?
According to the docs it is around 215mm long and should be mounted vertically. That would be a little hard to do with the Rx in a pot in the middle of the boat...

Anders

Anders
On the boat I use at the moment, which is the prototype for my own design, I have the antenna exit the top of the pot. Then it runs inside a tube, which leads aft, and up to clear the end of the boom at about 40deg.
On the production model the rx will be placed behind the sheet post so the antenna can stand vertical behind the boom, either in a tube or with a piece of elastic on the backstay.
Personally, I think the key point with this system is to have the antenna out in the open (and as vertical as possible) and not laying under the foredeck as is common practice.
The big bonus is with the TX antenna as this is on the tx module and very short. This means the radio can be placed completely inside a plastic bag when it rains. No antenna holes for water to run down. Imagine the scene with 20 skippers at the side of the pond and no antennas flying around

Hi all
This just came up from Rob Guyatt on the US IOM site

Hi All,
I've been using the Spektrum system for a few months and about my only comment is watch the antenna placement and orientation. Make sure they are both vertical and keep the rx antenna clear of other wiring. Range won't be an issue if you keep those points covered.

Regarding the SmartWinch, all new winches have no prob with Spektrum. But don't go out and purchase a new winch just for the Spektrum system. If you've got a pre April '05 model read the blurb on my web site. The issues are simple to solve and no money needs to be spent with some of the solutions for any model. If you don't want to change to the alternate wiring method then there's a couple of options requiring you to spend some. Please don't hesitate to ask me if you have any queries.

Cheers
Rob

Hope that is of some help.

I have a Disco with the small pot for the electrics. The rx antenna is cut to the 3.6" length. This allows the antenna to remain entirely inside the pot. On one occasion I had a range problem but that was corrected by rearranging the pot contents to keep the antenna away from the battery and battery leads.

Cheers
Rob

Rob Guyatt wrote:The rx antenna is cut to the 3.6" length

Hi Rob

Was wondering myself what length of antenna to use. The wavelength of a 2.4 GHz signal in a vacuum (more or less the same in air) is around 4.92 inches, and I'm usually told to make my aerial some integer fraction or multiple of the wavelength. If the exposed portion of the antenna is 3.6", d'you happen to know if there is around 1.3" of wire inside the RX module on its way to terminating on the internal PCB?

[Edited to get the arithmetic right!]

Hi Lester,
The antenna length inside the rx case is only a few mm. I was a bit puzzled about the difference as well but I have to put my hand up here and state that I'm not too clued up on rf. Bottom line is that the boat works well with Spektrum.

I've upload a pic to my web site.
http://users.bigpond.com/rmgsw/pictures/pictures9.htm

I've now seen the Spektrum system used by a number of people in a number of races.

First, the convenience is great. No more worries about available frequencies.

Second, as others have said it appears that the positioning of the antenna is critical. Seems that if the receiver antenna is not vertical, range goes down.

Third, the system is not "bulletproof", if out of range, the system "glitches" just like a conventional PCM or PPM system.

Fourth, as others have pointed out Spektrum requires some changes to work with some of the RMG winches.

All in all, while I plan to eventually purchase the Spektrum system, I'm not sure today which is the better choice--a high end pcm system or Spektrum. Spektrum is certainly an advantage if you are sailing internationally where "legal" frequency bands change from country to country. To my mind, though, Spektrum currently, doesn't seem as reliable and as fully "worked out" as a good Futaba or JR pcm set. One thing I would love to see is for someone to do a comparative range check on an installed Spektrum systm.

Lester has a point about antenna length. From my limited understanding of RF everything he says is right however I have installed a few wireless hotspots at work. Which also operate on 2.4Ghz and when I measured a couple or wireless hotspot antennas I found they were even shorter at 3.2â€

Received my system last week... and ofcourse the little engineer in me wanted to look what's inside ! :
http://el-servo.physics.helsinki.fi/per ... 05_may.htm

I don't have a compatible Tx yet but it is on order.

RoyL wrote:... One thing I would love to see is for someone to do a comparative range check on an installed Spektrum systm.

I might be able to do some testing when I get the Tx. Do you have any suggestions on how to do it ?

Anders

Anders,
To test range, just sail the boat away from you till the winch and rudder goes to fail safe positions. I did a simple test yesterday in the paddock behind the house. The boat showed no fault after I walked 180 m away. I used binoculars to see the boat was still resopnding. Just how much range do we need???????? Methinks there's not many venues that require binoculars.

Nevertheless, On the water may be a bit different so;

Probably a logical fail safe for each servo is sails full out and rudder hard over. At my club's venue
http://users.bigpond.com/rmgsw/pictures/pictures4.htm
http://users.bigpond.com/rmgsw/pictures/pictures6.htm
there's no risk of losing the boat.
I'll report back on the result of an on the water test next week.

Cheers

Yeah ! my 3VCS arrived today.

There seems to be a large price difference among shops. Mine came from Hong-Kong and I paid a reasonable 302 eur for Tx+ PCM module + R113IP Receiver and a 700 mAh battery.
I know there are good reasons for supporting local hobby shops but when they are asking 495 or 500+ for the same thing or with an FM Rx then at least I am happily ordering from abroad.

The customs officer was very keen on seeing a CE label on the radio since she claimed that otherwise she cannot give the radio to me. Happily there is a CE mark on the manual - but I was a bit scared while we were opening the package...

No ratchet plate for the sheet-stick was included so I'll have to source/build that myself.

Rob Guyatt wrote:Anders,
To test range, just sail the boat away from you till the winch and rudder goes to fail safe positions. I did a simple test yesterday in the paddock behind the house.

and then what ?? (I usually don't sail on confined ponds...)
I think I'll have to a test that is a little bit safer...

I've also ordered a 2 dBi omnidirectional WLAN antenna(95mm long) which I plan to test on the boat. Maybe a longer one (200mm) could also fit, that model would have 7 dBi gain and thus should give more range.

Anders

Hi Anders,
i've purchased a DSM system and am having range probs or should i say,not enough to be comfortable in a regatta.I understand you used one at the worlds and have done a mod to the reciever and your range is fine,could you fill us in?
I've also had words with Rob Guyatt who owns a Disco like myself and says he's working on a solution,but not conclusive as yet.
I have only sailed once so far and not started to experiment with antenna placement,so i might be lucky and this is all to do about nothing,nevertheless i'm hearing blurb about others having the same thing.Regards Peter

The range of the stock system is not that great, especially if you have the Rx in an RC-pot with only a little bit of the Rx antenna outside the pot.

My solution was to use a 2 dBi WiFi antenna as the Rx antenna on the boat. When I have time I will post pictures etc. on my website. In short I have soldered an SMA coax connector on the Rx, extended the antenna with a piece of RG174 coax cable to the aft deck and there I have a WiFi antenna just like the ones found on WiFi computer peripherals. The problem with this solution is that it is not that easy to implement and the connectors are not ideal and will corrode over time.

Rob Guyatt used a larger 5 dBi Tx antenna instead of the stock 2 dBi. This also seems to have the desired effect i.e. enough extended range.

Ken Binks had tried both the Futaba 3VCS and the Hitec equivalent and had surprisingly found that the range with the Hitec is much better.

Anders

Thanks for the reply Anders,
I am using it on an Optic 6 radio so it's good to know that the range is better than the Futaba,and yes the Rx is in a pot.I claim to be no expert on electronics as you two are,so i can see in a nutshell it's time to move back to FM mode for the time being as the radio has the synthesized module,i'll bet one of you guys are going to come out with a retrofit in the not too distant future,in the meantime i'll keep messing around with the antenna at the club,dont plan to be drilling holes all over my Disco,already taking lots of incoming Flak from my counterparts who have cheap radios lol!!! Peter

I've done some more fiddling with the range issue. Here's a link to an article on my web site.

http://www.rmgsw.com/Misc/Spektrum2.htm

Just to answer a couple of points from one of Anders earlier posts.
The 5 dBi antenna on top of my Sanwa is not that much of an improvement.
I'm puzzled by Ken Binks' experience with the 3VC vs the Hitec. I can't pick any difference in range between the two of them.

I didn't realise till I did the A class and IOM worlds this year just how popular the Futaba 3VC is. Thing is, I have all three and prefer the Hitec or the Sanwa over the Futaba. There's a couple of irritations I find using the Futaba not the least of which is the price!

Cheers

Rob Guyatt wrote:I didn't realise till I did the A class and IOM worlds this year just how popular the Futaba 3VC is

Hi Rob

In the UK, Ken Binks is the leading supplier to the trophy hunters. Like you, he has built an enviable reputation for straight dealing, standing by his products, and quick, helpful after-sales service. So when Ken says the Futaba 3VC is the one to use, well, we all just queue up patiently... (smile)

Can anyone tell me of any experiences with the Spektrum modules and a JR-X3810 ?
My friend has this radio on 35MHz for airplanes but would like to use it for his IOM also.


Also, if anyone has had a chance to try out the new Spektrum DX6 in an IOM, I'm sure the rest of the world would be eager to hear about the results !

Anders

Hi Anders,i suspect Steve Landeau and the others in California would know as they use JR equipment.I read somewhere that the DX6 will not be available until the end of Dec.I was told in San Diego that it's possible to go inside of the Tx module and turn up the transmission power,but not told how to do it,everything seems to be a big secret as that would prob be illegal,but you know what we'll do if we find out ,that coupled with Rob's antenna extension would be the ticket.I wonder if any of you guys know?or have i been had,i must admit he had a grin on his face.He's a wind up artist for shure but also good friends with the indivisual who created Spectrum.Peter

Hi, Anders.
I'm using the XP 8103 (same radio, different marketing name) and used the Spektrum at our Nationals. Both antennae (tx and rx) were modified and had no problems at all. Had plenty of range problems before changing the antennae though.

Hi
My intentions are to invest in the new Spectrum DX6 for my IOM once it gets out there. I would be greatful to see some pictures of antenna installations. As far as I understand there will be no problem using it within the IOM-circus.
Anyone disagree

Best regards

Hello Krister,
As is mentioned on www.IOM-Nordic.org, the DX6 is different than the one that is used as a module to existing radios. The Dx6 has twin receivers, so the antenna setup will be different than with the previous models. The Dx6 has two antennas.
The drawback is that it uses two channels - that means half the number of contestants....

Hello Kure

According to Spectrums own FAQ page:
"How many Spektrum-equipped cars can be run at the same time?

Up to 79 cars can be run at one time. As we all know, it's highly unlikely that this number will ever be exceeded, so from a practical point, you can run as many cars as you like."

I don´t quite understand what you mean by

The drawback is that it uses two channels - that means half the number of contestants....

As far as I understand there will be upto 79 contestants at the same time.

Is there anyone who has installed a unit in his boat and can provide any pictures??

Best regards

The first releases of the Spektrum system (like the one Anders Wallin uses), where made for cars. They use one channel - 79 people can race at the same time.
The Dx6 is made for aeroplanes. Since planes take loops and rolls, the
antenna is not allways pointing upwards (vital for the function). Therefore they made the twin solution. This way one of the antennas will receive allways (the idea anyway). But, it connects to two channels - only 39 can race at the same time if all of them use the Dx6.

Horizonhobby.com has the system available for mid December which probably means mid Jan,listed at USD$199.00,that's a pretty good deal considering i paid $160 plus for the module and Rx car system and $170.00 for the HiTec optic 6 radio.Hopefully it works and if it dont hopefully coaxing both antennas will solve that prob as well,i'm still trying to get some coax,guess we'll have to wait on the second generation ginueapigs.I'm quite enjoying my first computer radio,i'm not a one brand guy,i like the feature of shift select,being able to use any aftermarket Rx,i looked at that Airtronics radio and it looked pretty cool but was alot more dinero.Peter