Radio Signals Reflecting Off Water (Long Post)

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Radio Signals Reflecting Off Water (Long Post)

Postby pgfaini » Tue Mar 09, 2010 2:15 am

I finished wiring up my systems board, and tested my Spectrum DX6i TX, and my 3 channel MR3000 "Marine"RX. I used the throttle channel for the RMG Sailwinch, and the aileron control for the rudder. A problem arose with the aux. channel, needed for the jib trim. It was activated by the landing gear switch(CH.5), in effect, an on/off switch. I called Horizon Hobby, the importer, and explained that I needed that the elevator stick to connect to the aux. channel. After a long session of talking me through it, we were able to accomplish this via a programming called mixing. We, in effect, mixed (combined) the elevator and landing gear to operate simultaneously and then reduced elevator travel to +0 in both directions, and landing gear travel to +100, in effect, causing only the landing gear to output via the elevator commands.

Trials, showed excellent control of the jib trim, but no fine trim movement of the servo, although the display showed movement on the elevator. Checked the owner's manual, which stated only the four joystick channels had the trim feature. Another session with the tech. dept, revealed there was no way to mix the fine trim movements with the DX6i, although the DX7i had this feature. Bottom line, the MR3000 will not work for me. I inquired as to the signal range of the AR6000, a park flier receiver with extra long(for park fliers) antennae 3.75", and exceptional range. The Tech said there might be a problem with the signal reflecting off the water, due to the short antenna. I told him that no matter how long the antennae, the last inch which receives the signal can't be any higher than the deck, and 3.75" will reach the deck in our EC12's even if I have to raise the RX a bit.

I notice the antennae on the boat (Ricks?)on the web site has short antennae, maybe 4-5" at the most. Has there been any problems with signals reflecting off the surface of the water, causing loss of signal?

Sorry for the long winded post, but I thought I'd make everyone aware of the MR3000 shortcomings.
Paul
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Postby Rick West » Tue Mar 09, 2010 12:39 pm

Unfortunately, any time you mention boats and water to RC technical people what you get back is a sense that their equipment should not be there...If it is not flying it is not important.

The MR3000 is new and we have to rely on reports from the boating community. There have been very few systemic issues with radio gear we have used on the boats but when they get wet. Range has not been a proven issue. Some have said that antennas in the boats can be weaken on tacks where they are communicating through some water. I have never heard of a range problem dispite our antenna locations. The antenna you see on the site is a Futaba 2.4 unit without past reception issues.

Radio modifications or programming changes can be tested in the shop. If they work there history indicates they will work on the water. Range and invironment has not be an issue.

...94 [8D]
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Postby pgfaini » Tue Mar 09, 2010 2:31 pm

Thanks Rick, The problem with the MR3000, is that it was made for motorboats, not sailboats, and the third channel(aux) is locked into channel 5(Landing Gear), an on-off switch. The DX6i transmitter, is capable of mixing output channels, but not the trim controls. This means, that while you can get the third channel to operate off any of the four joysticks by mixing them with Ch. 5, the trim will not operate the servo, because ch. 5 has no trim. Since I can get the antennae of the AR6000 up as high as any other receiver's, I see no problem, but being new to RC boating, I was taken aback by the Horizon Hobby's tech remark about signal reflections, and came here to the source.[:D] Running far behind in getting the boat finished,looks like I'll be going to Atlanta with my camera, not #614.[:(]
Paul
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Postby Winston » Tue Mar 09, 2010 2:34 pm

One Question and One comment:

The "marine" Spektrum receiver comes with this statement "The MR3000 3-channel Marine receiver is specifically designed for boating applications and is compatible with all surface transmitters featuring the marine logo." Does your transmitter have the marine logo?

I still use my Spektrum DX6. The jib trim was moved to a home shop installation of a rheostat knob to avoid the problems with stick control. Other mods were to extend battery life and move tx antenna to inside the tx case. Works fine for 3+ years. I have never had ANY issues with this radio (although now that I have said that, I expect it to fall apart forthwith).
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Postby Tim » Tue Mar 09, 2010 3:00 pm

Paul,
I am in the process of refitting my boats with the new MR3000 (Rx). I hope to range test a couple weeks. I also use the DX6i (Tx)and ran into the same issue you mention concerning the Jib trim control.

I purchased a rotary potentiometer, removed the "Flap-Gyro" switch from the case and taped it inside the case & left wiring intact. Installed the new rotary potentiometer in the existing hole. Unsoldered the leads from the Rudder Stick and reattached them to the potentiometer. This modification has worked well for me. Please refer to the building site and check out this link, http://www.ec12.info/Radio-Mods.htm THis should help you.

My radio has also be back to "Horizon Hobby" for warranty work since and they honored the warranty. Needless to say I think Horizon Hobby tech support is great.

Tim [:)]
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Postby Tim » Tue Mar 09, 2010 3:10 pm

Winston,

The Spectrum MR3000 Rx uses DSM2 technology which is compatible with the DX6i transmitter regardless of the logos.

Tim [:)]
#484

The "marine" Spektrum receiver comes with this statement "The MR3000 3-channel Marine receiver is specifically designed for boating applications and is compatible with all surface transmitters featuring the marine logo." Does your transmitter have the marine logo?

I still use my Spektrum DX6. The jib trim was moved to a home shop installation of a rheostat knob to avoid the problems with stick control. Other mods were to extend battery life and move tx antenna to inside the tx case. Works fine for 3+ years. I have never had ANY issues with this radio (although now that I have said that, I expect it to fall apart forthwith).
[/quote]
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Postby pgfaini » Tue Mar 09, 2010 7:29 pm

Tim, I'd rather install an RX with four channels, and use the vertical RH joystick. The fine tune would be to adjust the jib in the event I miscalculated when trimming it on shore. The joystick for such as rounding a mark, and I expect if I pull it in quickly, what with the balance weight on the boom, it should work like a twitcher.
Paul
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Postby greerdr » Tue Mar 09, 2010 9:32 pm

I think a lot of attention to jib sub-trim could be better directed to "stick-time". I have the exact same mods as Winston and find the DX6 with a rheostat installed to be the best quick fix around this small issue.
Please bring 614 to Atlanta and enjoy some super people and a fine venue and don't worry about a jib trim.One missed tack or P/S error will remove any advantage gained by the jib 1/4 inch adjustment.
It is sort of like flying-you can get so caught up in the data you forget to aviate.
Come and sail.

R.C.Greer
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Postby Rick West » Tue Mar 09, 2010 10:33 pm

UH, I thought the gear was down.

...94 [8D]
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