rajul

My Feedback: (58)

Wind junkie, thanks for the excellent data. I would like to ask which Tx antenna orientation you found to be the most robust during your range tests? Which orientation is the worst?

da Rock

I wonder if remote antennas would be a solution for CF fuselages etc.

Asahi

Do you mean something like this?
http://www2.towerhobbies.com/cgi-bin...?&I=LXKX47&P=7

Could this negatively effect flight characteristics (mostly on smaller type planes)?

da Rock

Something like that.

But I would imagine that they would need to be engineered to suit the new frequencies. And the receivers would also need to be redone to accept them easily. I would really expect the mfg's to see the option as a very strong selling point. It addresses about the only real complaint that has been discovered with the new technology. What better way to gain a competitive advantage in the marketplace than to offer a competitive solution and better performance and solve a problem as well.

Whip antennas have been used on lots of models very, very successfully. The effects on flight have not been of any consequence. Most smaller type planes wind up with great lengths of fluttering, trailing antenna as it is. And nobody has noticed any real problems other than stepping on them.

And btw, if you place a round rod at an angle to the airflow it becomes more of an eliptical shape to the airflow. It becomes more streamlined. And the drag is measurably reduced. It's one reason lots of whip antennas are raked.

wind junkie

My Feedback: (1)

When I did the original range checks, it seemed that I got the best performance when I pointed the antenna about 45 degrees to the plane. The worst was when I pointed the antenna away from the plane. However, it's important to realize that once I lost control (Spketrum systems go into "last held position" rather than jitter) I was often walking backwards and then I abruptly stopped, and moved the TX in all orientations (including pointing away from the model). It was very very rare for a re-orientation of the TX antenna to regain control once control was lost. The only thing that helped was stepping forward one or two paces. At that point, I would then repeat the re-orientation process, and it was also very rare that the antenna orientation seemed to make a difference (at least within 2 paces as far as I could tell). But if memory serves, sometimes when I was at the critical distance just on the threshold of working and not working, 45 degrees was best, and 180 degress was worst.

BillPTC

Has anone tried the AR6200 Rx yet.
Bill PTC

da Rock

wind junkie,
I believe signal strength fields of different type antenna is documented and spells out the areas of strength and weakness for different types of antenna. Sorry I don't have any links on the subject. In a hurry and wanted to mention it before going out the door. Will try and look it up later.

Bad_Daddy

CF is conductive material - the carbon fibers themselves are more conductive than aluminum. Therefore, you are trying to get a signal to penetrate a conductive tube (also known as a Faraday cage) which is exactly how any circuit builder surrounds circuits to eliminate RF interference. Test all you want, but unless you learn how to re-write the laws of radio wave propagation, CF tubes (and rods and beams) will always act as an RF barrier, even locally.
Test this: Remove the RX from the fuselage but tape it to the outside, along one side of the fuse Then perform a range check from the opposite side of the fuselage.

daveosoar

Keep going guys, the more you all run to 2.4 the better I like it! In the Uk we use 35Mhz and can change to any unit within the band at will ( I have 12 sets of Xtals now). Ihave never been caught out at a comp once having registered. Go to it boys and leave me more space on my 35Mhz band, after all I've only approx 40 channels to choose from, ---- and the price per set of Tx/Rx Xtals is falling! At 69 years old the manufacturars will have to work very hard and drop the price to get me to abandon 2 x Tx and 15 Rx with the ability to stick in the Xtals I need on any one day. ------15 2.4 Rxs? The cost? I dont think so!
Daveosoar.

aeajr

My Feedback: (2)

Davesoar,

May you enjoy 35 Mhz for many years to come.

da Rock

I too appreciate the hurried transition to this new technology. I'm on 72 and forsee an ever increasing isolation there. Hooo hahaaaaa !!!!!

I owned about 8 TXs back when the rules changed and the US gummit decided they weren't good enough to live any longer without somewhat expensive changes. I put all my equipment into a box, all the airplanes on the walls and changed hobbies. Missed the airplanes way too much and decided that once again, more government sucks. Getting back into the hobby after many years, I chose to go with a synthesizer TX and have accumulated a decent stock of RXs. Nice RXs, and all quite affordable. And all with your everyday, plug-in crystals.

I tell every newby about the price of RXs, and the flexibility of 2.4GHz. And pray that they'll do the 2.4GHz deal.

I do love the freedom YOU GUYS ARE EMBRACING. Hooo hahahaaaaaaaaaaaaa

aeajr

My Feedback: (2)

BTW, 2.4 friendly fuselages are also more friendly to 35 and 72 MHz radio systems than carbon fuselages. 72 and 35 are also impacted by carbon or metal in the fuselage. However because they use those long antenna they can tollerate it better, you just have to deal with the long antenna. Of course 35 and 72 are more subject to interference and shoot downs, so they carry thier own issues, but those are also not the topic of this discussion.

edited to remove offtopic text
The remaining text is also not specific to the title of the thread but is close

vultureflight

Admittedly, I have not searched the forums for an answer to this question, so forgive my laziness... I primarily fly wood TD sailplanes and 95% fiberglass (localized - base of the T-tail and wing roots - kevlar and/or carbon reinforcement) TD sailplanes. Any high altitude/long distance 2.4 Ghz range problems experienced with these birds? I'm about to switch entirely to 2.4 Ghz equipment...

aeajr

My Feedback: (2)

You should have no problems at all with the Spektrum/JR, XPS or the Futaba systems.

vultureflight

Thanks for the quick reply, Ed!

wind junkie

My Feedback: (1)

I have another update on my AR7000 installation. I recently got the Spektrum module to use with my 9303. No more funky programming trying to cram a 6 servo sailplane into the DX7.

I flipped the AR7000 around in the nose of my plane so the small antennae of the main RX are now away from the large 5 cell nimh battery. That made all the difference IMO. With this setup, I had a very enjoyable flight on Friday -- totally glitch free and far enough away to prove reliability -- both in the air and via range check. The range check exceeded 40 paces this time so I was confident in heaving it over the water.

Here are some pics courtesy of Dave Garwood:

BMatthews

WJ, in an earlier post you asked about using longer wires for the antenna. This isn't something you can do readily without a lot of checking.

Using a wavelength calculator online at http://www.onlineconversion.com/freq...wavelength.htm I figure that the antenna on the AR6000 are already at the 3/4 wavelenth value. They've obviously tuned the receiver to work with that length and altering it would be risky at best.

I'm not sure what they are using on the other receivers.

From your tests as well as the sad outcome to TooManyPlane's glider it's fairly obvious that we can't continue to do business in the old manner. Placing the antenna close to other components is just not a good practice. We get away with this on the 72 mhz equipment because running the antenna past a component or two involves such a small portion of the overall length. But how we have a situation where a single servo or battery pack can look like a Chevy to the antenna just thanks to relative sizes.

I think the true key is going to be to mount the Rx in such a way that the antenna wires can stub out into the wings to ensure they are as clear of the other radio components as practical.