Radio Hits!!!!
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Radio Hits!!!!
I'm running out of ideas on this problem and so far nothing seems to work. Here's whats happening;
I get quick glitches at each end of the runway at the same places. This also happens up to 150 to 200 ft straight up from the runway ends, and if you were to stand center runway straight out to each end i get hit when passing through these zones. I sometimes get them in other areas while flying but its infrequent and random. The hits are very quick 1 second or less
The planes pitch violently up or roll or yaw. This is troublesome on landings as the planes always balloon at these spots. Some members claim it to be the wind swirling up the hill. But no way is the wind causing my throttle servo to move! My planes are getting larger and more expensive and I don't enjoy nor can I relax when flying.
All FOUR of my planes do this( 3 glow 1 gas), I have moved things around inside each and no change. The gasser is more affected. My first radio was a tx6as on #43. I had this problem then but didn't notice too much because I was green. Second radio was a 8u # 53 with the same problems. I now have the new 9c on #53 still getting hits. I chose these channels because they're not used by anyone else in the club. Our club is small and there's several channels empty.
In the early spring and fall I fly at the in-laws place (large bean field) and I get absolutely no hits whatsoever. Flying here is much more enjoyable until the tractors show up and I'm forced back to the clubs field. I have come to the conclusion that my places are fine and it's something at the field. No one else there seems to have this problem or at least haven't spoken up. There are no other clubs around with a reasonable driving distance.
When asking around about this I get nothing, no ones heard of this happening. Should I try a different channel say, high 60's or seventy's? I could try one of the more popular ones but was trying to avoid the accidental turn on. I don't know, the beans will be out in a month so I'll be good till spring. But flying alone gets old and probably not too safe.
If anyone has ideas, thoughts or anything please post. Sorry for the length but thought a good explanation would help.
Thanks,
Dave
I get quick glitches at each end of the runway at the same places. This also happens up to 150 to 200 ft straight up from the runway ends, and if you were to stand center runway straight out to each end i get hit when passing through these zones. I sometimes get them in other areas while flying but its infrequent and random. The hits are very quick 1 second or less
The planes pitch violently up or roll or yaw. This is troublesome on landings as the planes always balloon at these spots. Some members claim it to be the wind swirling up the hill. But no way is the wind causing my throttle servo to move! My planes are getting larger and more expensive and I don't enjoy nor can I relax when flying.
All FOUR of my planes do this( 3 glow 1 gas), I have moved things around inside each and no change. The gasser is more affected. My first radio was a tx6as on #43. I had this problem then but didn't notice too much because I was green. Second radio was a 8u # 53 with the same problems. I now have the new 9c on #53 still getting hits. I chose these channels because they're not used by anyone else in the club. Our club is small and there's several channels empty.
In the early spring and fall I fly at the in-laws place (large bean field) and I get absolutely no hits whatsoever. Flying here is much more enjoyable until the tractors show up and I'm forced back to the clubs field. I have come to the conclusion that my places are fine and it's something at the field. No one else there seems to have this problem or at least haven't spoken up. There are no other clubs around with a reasonable driving distance.
When asking around about this I get nothing, no ones heard of this happening. Should I try a different channel say, high 60's or seventy's? I could try one of the more popular ones but was trying to avoid the accidental turn on. I don't know, the beans will be out in a month so I'll be good till spring. But flying alone gets old and probably not too safe.
If anyone has ideas, thoughts or anything please post. Sorry for the length but thought a good explanation would help.
Thanks,
Dave
#3
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Radio Hits!!!!
Are there any chain link fences in close proximity? Any large area metal buildings? I have seen where a chain link fence relatively close to where the pilot stood, would create areas where the plane would glitch. It you stood right next to the fence (lean on it) while flying, there were no glitches. If the distance to the fence from the pilot was exactly 1/2 wavelength or close odd multiple, the signal would cancel out in certain areas. Strange but it happened.
#4
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Radio Hits!!!!
If you can affort it, a scanner would be an excellent investment to check band activity around areas where you are getting hit.
There is one out there made by ICOM, which has a scope function, and you can visually see what is going on in the whole 72MHz band or specific channels. Model number is IC-R3. Check it out on
http://www.icomamerica.com/
Most of the jet guys at my feild use this. You can get it at Ham Radio Outlet for around $350.
http://www.hamradio.com/
Another alternative is to just try other channels.
Mike
There is one out there made by ICOM, which has a scope function, and you can visually see what is going on in the whole 72MHz band or specific channels. Model number is IC-R3. Check it out on
http://www.icomamerica.com/
Most of the jet guys at my feild use this. You can get it at Ham Radio Outlet for around $350.
http://www.hamradio.com/
Another alternative is to just try other channels.
Mike
#5
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Radio Hits!!!!
Alot of times when you experience glitches close to the ground it's possible that it's just the way the wind is bouncing off the ground.. It creates a rolling effect down the field and can suck the plane down or push it up very quickly without warning.. That happens at our field when the wind is coming from the south. The far end of our field is like the bermuda triangle... mysterious
Just another possibility for you.
Just another possibility for you.
#6
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Radio Hits!!!!
Indeed - you can get rollers (wind) off of the end of the runway, plus if you are using a paved runway you will get air rising from the hot runway surface, causing a form of windshear at the runway edges, etc - however, the originator of the post already pointed out that the problem includes the fact that his throttle servo moves (presumably he hears the pitch change), so in that case the problem isn't wind related.
Gordon
Gordon
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Radio Hits!!!!
The fence at our field is plastic but held with steel post. I always stand in the same spot or close to it. Don't know if that matters any or not. Everyone stands next to the fence though.
I was told before the club was opened the area was scanned and checked out ok. Runway is grass, though an old landfill, don't know if that matters any either.
It's not the wind as I can here my engines rpm increase/decrease when the hits occur and I know I'm not moving the stick. During landing I'm at idle so this eliminates wind.
Might just buy a module and one crystal to see what happens. Does anyone know if I have to stay on high band? I'm on 53 now but could I try something in the 30's as long as both are the same obviously. Do the 8U and 9C use the same module?
Thanks
Dave
I was told before the club was opened the area was scanned and checked out ok. Runway is grass, though an old landfill, don't know if that matters any either.
It's not the wind as I can here my engines rpm increase/decrease when the hits occur and I know I'm not moving the stick. During landing I'm at idle so this eliminates wind.
Might just buy a module and one crystal to see what happens. Does anyone know if I have to stay on high band? I'm on 53 now but could I try something in the 30's as long as both are the same obviously. Do the 8U and 9C use the same module?
Thanks
Dave
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Radio Hits!!!!
I was about to make a new post when I saw yours.... I noticed it the last time I lew last week, and again today...
I get a hit at about 200 yards out from the center of the runway, and about 30-50 ft up in both directions. At first I thought it was wind or thermals comeing off the pavement or something but I can hear big RPM changes as well... It happens on all three of my planks but oddly not on any of my chopers (but I guess I really don't take them out to that zone)...all of which are glow..... and it's so damn predictable... probably happens on 1 of 5 approaches but never on take off. I've been flying at this sot for well over 2 years on the same channel and have never had such a problem. The spot is in a very rural area .... probably only a few hundred people for a 45 mile radius.
The odd thing is when I go to the AMA field (I fly at this old abandoned country airport) I sometimes get the same hit in the exact same locations and always on approach.
My Radio is a 8Uafs, and I run all PPM Futaba RX's on CH 47
Any Ideas?????
I get a hit at about 200 yards out from the center of the runway, and about 30-50 ft up in both directions. At first I thought it was wind or thermals comeing off the pavement or something but I can hear big RPM changes as well... It happens on all three of my planks but oddly not on any of my chopers (but I guess I really don't take them out to that zone)...all of which are glow..... and it's so damn predictable... probably happens on 1 of 5 approaches but never on take off. I've been flying at this sot for well over 2 years on the same channel and have never had such a problem. The spot is in a very rural area .... probably only a few hundred people for a 45 mile radius.
The odd thing is when I go to the AMA field (I fly at this old abandoned country airport) I sometimes get the same hit in the exact same locations and always on approach.
My Radio is a 8Uafs, and I run all PPM Futaba RX's on CH 47
Any Ideas?????
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Radio Hits!!!!
I'd give the radio a good range check with the planes engine running and the antenna full down.. We have had the same problem on several planes and with a range check found the radio output was low.
The plane would respond OK in the air, but down low on takeoff or landing approach, when the pilot was standing with the antenna aimed at the plane, which is usally the case, we would get glitches. If the plane pitches down instead of up, your in a heap of trouble.
When the radios were sent in for service, the repair ticket showed a bad ceramic filter and crystal.
Cajun
The plane would respond OK in the air, but down low on takeoff or landing approach, when the pilot was standing with the antenna aimed at the plane, which is usally the case, we would get glitches. If the plane pitches down instead of up, your in a heap of trouble.
When the radios were sent in for service, the repair ticket showed a bad ceramic filter and crystal.
Cajun
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Does it....
Does it happen only when the plane is arriving at the end of the runway? What about when the plane is departing the same end headed the outbound direction. I like the suggestion about the radio check. check the plane, on the same angle, from 70 feet away.
During a complete radio range check, I have done a complete circle around a few planes, out at a 70 ft radius, and noticed that some angles appear significantly more prone to interference. Make sure the engine is running when you do this.
Do the circle check with your plane in the location where you get the hits, and again after having moved the plane to a completely different part of the field.
During a complete radio range check, I have done a complete circle around a few planes, out at a 70 ft radius, and noticed that some angles appear significantly more prone to interference. Make sure the engine is running when you do this.
Do the circle check with your plane in the location where you get the hits, and again after having moved the plane to a completely different part of the field.
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Radio Hits!!!!
I have a couple of thoughts on your problem. One involves your rx, one involves your tx. I'm a ham, so things like antennas and signals are kinda interesting to me.
Regarding your rx, has it ever been in a crash? My thoughts are that it might be damaged. It could be that perhaps the radio isn't picking up the signal as clearly as it could, due to a fractured crystal, or an internally damaged antenna wire.
It could be that when you are in your 'zones', you are low to the ground. When you go out beyond those zones, perhaps you are higher up, thus helping your rx to pick up your signal marginally better, and masking the real problem. When you are coming across the field, your tx is close to your airplane and it doesn't have a problem picking up a signal.
As for not having a good signal when the plane is overhead, I could expect that because of the design of the tx's antenna. A vertical antenna radiates very poorly off its tip. If you were to 'aim' your tx at your plane (which is what you are doing, in essence, when it is overhead), then this is the position where your rx is getting the least amount of signal from your tx.
Can you borrow another receiver on the same channel and install it to test this theory out?
If it turns out to be the rx, then put your rx back in the plane, and see if you can use the other plane's crystal. In any event, don't fly an airplane that has a possibility of losing control.
You could also have a tx problem, where the tx is not putting out full power. This could be caused by low battery voltage, or a bad output transistor that won't give full tx output.
It could be that your tx batteries are weak, or the tx is perhaps otherwise damaged. Does your tx have a meter or digital readout showing the tx's battery pack voltage?
How could you damage your tx's output transistor? Easily. Just leaving the tx on with the antenna collapsed for extended periods could overload the output transistor. It's OK to do this for a short period of time to do a ground check or start your engine, but the tx isn't designed to handle a signal into a collapsed antenna for a long period of time.
All the other theories in this thread are also possible, I'm just adding an extra one.
Just my $.02
Bob
Regarding your rx, has it ever been in a crash? My thoughts are that it might be damaged. It could be that perhaps the radio isn't picking up the signal as clearly as it could, due to a fractured crystal, or an internally damaged antenna wire.
It could be that when you are in your 'zones', you are low to the ground. When you go out beyond those zones, perhaps you are higher up, thus helping your rx to pick up your signal marginally better, and masking the real problem. When you are coming across the field, your tx is close to your airplane and it doesn't have a problem picking up a signal.
As for not having a good signal when the plane is overhead, I could expect that because of the design of the tx's antenna. A vertical antenna radiates very poorly off its tip. If you were to 'aim' your tx at your plane (which is what you are doing, in essence, when it is overhead), then this is the position where your rx is getting the least amount of signal from your tx.
Can you borrow another receiver on the same channel and install it to test this theory out?
If it turns out to be the rx, then put your rx back in the plane, and see if you can use the other plane's crystal. In any event, don't fly an airplane that has a possibility of losing control.
You could also have a tx problem, where the tx is not putting out full power. This could be caused by low battery voltage, or a bad output transistor that won't give full tx output.
It could be that your tx batteries are weak, or the tx is perhaps otherwise damaged. Does your tx have a meter or digital readout showing the tx's battery pack voltage?
How could you damage your tx's output transistor? Easily. Just leaving the tx on with the antenna collapsed for extended periods could overload the output transistor. It's OK to do this for a short period of time to do a ground check or start your engine, but the tx isn't designed to handle a signal into a collapsed antenna for a long period of time.
All the other theories in this thread are also possible, I'm just adding an extra one.
Just my $.02
Bob
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Radio Hits!!!!
Well, I flew one this morning and stood at different places on the field. I noticed the hits would move around a little. Some places it got a little worse and some the same. One guy showed up later on and we decided he would follow me around in the air. Places where I got hit he flew through fine. He is on channel 27 I believe. His stuff was JR so we couldn't swap. I will just get a module and crystal and see what happens.
I have four plane that do this so I would think It might be something else but I could be wrong.
Dave
I have four plane that do this so I would think It might be something else but I could be wrong.
Dave
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Radio Hits!!!!
That's a thought, but are they all controlled by the same transmitter? If so, I am wondering if the transmitter could be the common denominator.
Here's something that just occurred to me... make sure that your antenna is screwed in!
I was getting a lousy ground check and just happened to grab the collapsed antenna. It came off in my hand. I dodged a bullet on that one!
It might be that your antenna is loose (but not totally unscrewed), giving an intermittent signal. I'm thinking it might be that it's giving you poor power output.
Just trying to think of possibilities... Can you borrow another transmitter on your freq? Then, fly the plane from the same position and see if you get the same hits....
Just another thought...
Bob
Here's something that just occurred to me... make sure that your antenna is screwed in!
I was getting a lousy ground check and just happened to grab the collapsed antenna. It came off in my hand. I dodged a bullet on that one!
It might be that your antenna is loose (but not totally unscrewed), giving an intermittent signal. I'm thinking it might be that it's giving you poor power output.
Just trying to think of possibilities... Can you borrow another transmitter on your freq? Then, fly the plane from the same position and see if you get the same hits....
Just another thought...
Bob
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Radio hits
Davham,
Let's be logical on this.
1 - You have used 3 different TXs, and the problem happend on all 3. So, let's rule out the TX as the problem's source, nearly impossible to get 3 bad TXs in a row.
I suppose we haven't used the same TX battery. If so, replace it and test again on any of your radios.But this is unlikely as the radios you are using have low Batt warning bips.
2- You didn't said if you kept the same receiver with the 3 different TXs.
a- If used different receivers, discard it as the problem.
b- if used the same receiver but exchanging crystal, it could be a faulty RX. Replace the RX and if the problem goes away, it's the culprit.
3- You had flown in a different place and never got hits.
4- Keep your RX antenna fully extended, don't coill it or make bends to fit nicely inisde the fuse, you will get hits for sure. 90% of the cases are traced to this root cause.
5- Intermodulation between TXs could be a cause, but this unlikely as you had used 3 different frequencies. AS a precaution
just keep 10 feet away from another TX turned on, 20 feet would be much better.
If none of the above, most likely there is something trasmitting on the filed's area. possibly and not so large power and your TX signal gets to your RX stronger most of the time. At certain spots, or where places where you point your TX antenna in a bad way, it could overcome your TX signal temporarily.
We have a similar problem on our field, on channel #27. It hits any TX or RX, for whatever brands we tested. There just someone transmitting ou there and we just banned this frequency.
There is no fence or any metallic structure less than a mile on all directions from our field.
PCM will not get rid of interference, it just blocks controls going to the fail-safe mode. During this it will NOT accept any command from your TX. People ussualy thinks it will overcome interference, the signal transmision and receiver demodulation is just plain FM like ordinary radios.
Hope this will help you find out the problem. A scanner will help you but it's more $$ spent, probably shared by club members would be affordable.
Let's be logical on this.
1 - You have used 3 different TXs, and the problem happend on all 3. So, let's rule out the TX as the problem's source, nearly impossible to get 3 bad TXs in a row.
I suppose we haven't used the same TX battery. If so, replace it and test again on any of your radios.But this is unlikely as the radios you are using have low Batt warning bips.
2- You didn't said if you kept the same receiver with the 3 different TXs.
a- If used different receivers, discard it as the problem.
b- if used the same receiver but exchanging crystal, it could be a faulty RX. Replace the RX and if the problem goes away, it's the culprit.
3- You had flown in a different place and never got hits.
4- Keep your RX antenna fully extended, don't coill it or make bends to fit nicely inisde the fuse, you will get hits for sure. 90% of the cases are traced to this root cause.
5- Intermodulation between TXs could be a cause, but this unlikely as you had used 3 different frequencies. AS a precaution
just keep 10 feet away from another TX turned on, 20 feet would be much better.
If none of the above, most likely there is something trasmitting on the filed's area. possibly and not so large power and your TX signal gets to your RX stronger most of the time. At certain spots, or where places where you point your TX antenna in a bad way, it could overcome your TX signal temporarily.
We have a similar problem on our field, on channel #27. It hits any TX or RX, for whatever brands we tested. There just someone transmitting ou there and we just banned this frequency.
There is no fence or any metallic structure less than a mile on all directions from our field.
PCM will not get rid of interference, it just blocks controls going to the fail-safe mode. During this it will NOT accept any command from your TX. People ussualy thinks it will overcome interference, the signal transmision and receiver demodulation is just plain FM like ordinary radios.
Hope this will help you find out the problem. A scanner will help you but it's more $$ spent, probably shared by club members would be affordable.
#17
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Radio Hits!!!!
If you are using dual conversion receivers, third order modulation will not be the cause. As to being seperated from other xmtrs, WRONG, WRONG,WRONG. You are most imune from interference from each other the closer you are together. Some rather extensive test have been made on this and, in all cases, least interferance was caused when the transmitters were withing just a few feet of each other. I believe it was Ed Henry, the guy who does the MicroHenrys in Model Aviation who spearheaded this test back in the days of mostly single conversion receivers. I have heard that it has been confirmed several other places. With dual conversion, no problems unless the nearest Xmtr is so strong it drowns out all other signals by closing down the AVC control in the receivers.
If the dead band locations (where the plane is when you get the hits) changes when you change the position of the transmitter, chances are you are getting a reflection from some nearby object that subtracts from the total signal strength the receiver sees. Are you sure there is no metal building, fence or other structure nearby. If there is, move right up next to it and see if the deadbands or spots dissappear or move locations.
If the dead band locations (where the plane is when you get the hits) changes when you change the position of the transmitter, chances are you are getting a reflection from some nearby object that subtracts from the total signal strength the receiver sees. Are you sure there is no metal building, fence or other structure nearby. If there is, move right up next to it and see if the deadbands or spots dissappear or move locations.
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Radio Hits!!!!
Well, that's what I get for just glancing over the first paragraph of the thread - I completely missed the fact that there were three tx's in use. Mea Culpa.
Sharp333 and Rodney both have good points. However, here is another... Did you know that what we know as the R/C bands are not totally dedicated to our use? We share the bands with some industrial frequencies. Are there any industrial or utility services in the area?
Bob
Sharp333 and Rodney both have good points. However, here is another... Did you know that what we know as the R/C bands are not totally dedicated to our use? We share the bands with some industrial frequencies. Are there any industrial or utility services in the area?
Bob