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Sep 13, 2019, 06:43 PM
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Quote:
Originally Posted by Lufo
Is the model on the ground or elevated? IF on the ground it may well fail the range test if your back is turned to the plane. If not elevated then elevate the plane about 1 meter and do a range test again.

I would also open the receiver case and ensure both antenna are well attached to their snap mounts.

Even though the receiver and antennas are sort of close to the ESC the ESC not providing power to the motor ( idle state ) should not interfere with range testing.
The model was on a table about 30" off the ground.

I will move the antennas away from the ESC as far as possible. How important is it that the antenna ends are at 90 degrees to each other? I presume it also helps to have the antenna ends as far apart from each other as possible?

Thanks for the tip on checking the antenna mounts.... did not think about that.
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Sep 13, 2019, 07:27 PM
Registered User
Quote:
Originally Posted by Klausim
The model was on a table about 30" off the ground.

I will move the antennas away from the ESC as far as possible. How important is it that the antenna ends are at 90 degrees to each other? I presume it also helps to have the antenna ends as far apart from each other as possible?

Thanks for the tip on checking the antenna mounts.... did not think about that.
Various opinions on antenna positioning. Ideally, in an ideal world where nothing moves the 90 degrees is great. In the same world if something always moved on the same x-y plane the 90 degrees would be great. In our world of hobby flying, especially 3d / aerobatics nothing is an ideal positioning. My opinion is that as long as the two antenna are not taped or bound to each other and are not closely parallel or, the antenna or antennas, are not parallel to metal / carbon pushrods or noisy electronics such as an ESC .... the placement does not much matter. Of course you do not want to bury them in a carbon fiber nose cone either.

I try to have one antenna on the inside bottom of the fuse running length wise and one antenna to be upright as much as possible. Sometimes that upright might be in a convex arch across the inside of a nose running across the top, left to right.

Many will disagree with my above opinion on placement and will quote you many engineering stats but the bottom line is you put a one antenna receiver in a plane and fly 3d you will see it does not matter how the antenna is placed as long as it is not interfered with by carbon fiber, electronics, etc.
Last edited by Lufo; Sep 13, 2019 at 07:34 PM. Reason: clarity
Sep 13, 2019, 07:32 PM
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Quote:
Originally Posted by Klausim
The model was on a table about 30" off the ground.

I will move the antennas away from the ESC as far as possible. How important is it that the antenna ends are at 90 degrees to each other? I presume it also helps to have the antenna ends as far apart from each other as possible?

Thanks for the tip on checking the antenna mounts.... did not think about that.
Your one meter height is good and frankly, doing a range check with my MC-20 I can move 10 or 15 meters from my gliders, turn my back to the gliders and still have a signal ... a weak signal but a signal none the less.

Are you by chance keeping a cell phone on your body with the wi-fi activated? The wi-fi will/can interfere with the transmitter signal; if someone tells you otherwise simply ignore them.
Last edited by Lufo; Sep 13, 2019 at 07:51 PM. Reason: correct values
Sep 13, 2019, 08:23 PM
Rust: The poor man's Loctite.
TomM's Avatar
Quote:
Originally Posted by Lufo
Various opinions on antenna positioning. Ideally, in an ideal world where nothing moves the 90 degrees is great. In the same world if something always moved on the same x-y plane the 90 degrees would be great. In our world of hobby flying, especially 3d / aerobatics nothing is an ideal positioning. My opinion is that as long as the two antenna are not taped or bound to each other and are not closely parallel or, the antenna or antennas, are not parallel to metal / carbon pushrods or noisy electronics such as an ESC .... the placement does not much matter. Of course you do not want to bury them in a carbon fiber nose cone either.

I try to have one antenna on the inside bottom of the fuse running length wise and one antenna to be upright as much as possible. Sometimes that upright might be in a convex arch across the inside of a nose running across the top, left to right.

Many will disagree with my above opinion on placement and will quote you many engineering stats but the bottom line is you put a one antenna receiver in a plane and fly 3d you will see it does not matter how the antenna is placed as long as it is not interfered with by carbon fiber, electronics, etc.
I am an engineer and government consultant in antennas and RF communications, and your assessment is spot-on. In a dynamic situation where both antennas (few people stay still while holding the transmitter) are constantly changing orientation, initial position means little.

Besides the things you listed as carbon fiber, avoiding parallel wire runs with the antenna, I've found another potential problem is the inboard servos, either pushrod connected on a pull-pull rudder application, where the receiver antenna could be within a couple inches of a digital servo. Avoid that and try to run the antenna in a direction away from servos, because some are very electrically noisy.
Last edited by TomM; Sep 13, 2019 at 08:33 PM.
Sep 13, 2019, 11:36 PM
Registered User
Lufo, TomM, thank you for your valuable feedback.

As to the cell phone, yes - I carry my cell phone in my pocket and wi-fi is enabled. I have been flying like this for many years and never had an experience like this with my Spektrum radio. With Spektrum receivers you usually have 1 or more additional satellite receivers in your model.

I was hoping that Graupner RX connection would be better or at least as solid. I did not get off to a good start but I am grateful for the community support provided on this forum.

For now I will re-arrange the antennas as per your suggestions and continue re-arranging until I have a positive range check.
Sep 14, 2019, 08:05 AM
Rust: The poor man's Loctite.
TomM's Avatar
FWIW, I've lost the returning telemetry link a few times while doing a range test in different brands of radios. While I never measured the power, I do know the return telemetry power is a fraction of the transmitter power, so I don't worry about it. For my range check, if I can't see the deflections, I usually have an assistant watch for steady sinuous movements and report any stuttering or stopping.
Last edited by TomM; Sep 14, 2019 at 08:54 AM.
Sep 14, 2019, 08:52 AM
Registered User
It occurs to me now that Graupner have mentioned here several times to not be too concerned about weak returning telemetry link or telemetry numbers as that could at times, be weaker than the primary transmitter signal and is not an indicator of transmitter strength to the receiver.
Last edited by Lufo; Sep 14, 2019 at 09:01 AM. Reason: spelling , grammar
Sep 14, 2019, 10:40 AM
'n boer maak 'n plan
yufasa's Avatar
Klausim clearly states that the model goes onto failsafe so the Tx signal is definitely an issue and need to be corrected before flying.

There is a lot of good advice here but I am concerned about the receiver as it normally is easy to find a good spot that will work in most models.
Sep 14, 2019, 11:07 AM
Rust: The poor man's Loctite.
TomM's Avatar
I re-read the thread and saw the failsafe part and the picture of the installation. That is a very dense installation and I would say your antennas are too close and parallel to the servo wires, Id really try working on a different layout that puts the antenna in some free space. Another option is to buy the Graupner 6" antenna and move them away from the wire mass.
Sep 14, 2019, 11:27 AM
Registered User
Quote:
Originally Posted by yufasa
Klausim clearly states that the model goes onto failsafe so the Tx signal is definitely an issue and need to be corrected before flying.

There is a lot of good advice here but I am concerned about the receiver as it normally is easy to find a good spot that will work in most models.
Well aware of that and is why I mentioned in my post to Klausim about antenna placement. I was simply responding to TomM post about the telemetry down link. It may be of value to others.
Sep 15, 2019, 05:52 PM
Registered User
Just to report quickly on my progress: re-routed both antennas away from all servo wires, along the inside of the fuselage. One pointing down and the other pointing forward.
Range check this time was no issue up to a distance of 80m. Even with the TX behind my body at 60m I only lost telemetry signal but not TX signal. I am happy with that.

Thanks again to all for your valuable input.
Sep 15, 2019, 05:57 PM
Registered User
B.T.W, is there something similar to a "TX inactivity" warning that can be set in case the TX has had no control movements for, lets say, 10 minutes a warning goes off as a reminder to turn the TX off? I found this very handy on my DX-18.
Sep 15, 2019, 06:20 PM
'n boer maak 'n plan
yufasa's Avatar
Absolutely - I believe it is in the system tab but don’t remember from top memory. will have to check when I get home
Sep 15, 2019, 06:58 PM
Registered User
Quote:
Originally Posted by Klausim
Just to report quickly on my progress: re-routed both antennas away from all servo wires, along the inside of the fuselage. One pointing down and the other pointing forward.
Range check this time was no issue up to a distance of 80m. Even with the TX behind my body at 60m I only lost telemetry signal but not TX signal. I am happy with that.

Thanks again to all for your valuable input.
Congratulations to resolving the issue! Glad we could be of help to you.
Sep 16, 2019, 12:34 AM
Registered User
Quote:
Originally Posted by yufasa
Absolutely - I believe it is in the system tab but don’t remember from top memory. will have to check when I get home
I found it! It's in the Special tab under System Notice - Controls Sleep Time.

It was set to 30 minutes and that is why it never came on before. Changed it to 10 minutes now to keep me on my toes.


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