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Airworthy Radios and Installations (a few thoughts)!

Hai-Lee

Old and Bold RC PILOT
#22
I have gotten 2 mile range with my older single antenna Flysky.
Why do people get their individual achievements confused with a technical specification or what is a performance specification.

I raised this topic to try and help those who are starting out in the hobby to understand the need for, and how to select a reliable and suitable radio system or at least to know what type of radio system will give them the best and most reliable performance/communication. This would thereby make their experience better and safer. Surely a radio system without inherent LOS issues would be better for all.

Individual examples of what once worked are unfortunately less helpful than what will always work in keeping the fixed wing RC aircraft in communication and under control. Personally I started working with wireless networking and spread spectrum technology back in the early 1990s when NCR released their wireless networking products and was at one time a fully qualified Cisco wireless associate. I know how to squeeze range out of 2.4GHz radios but the OP was to help those keep their craft in the air throughout their entire flight.

Of late I have been looking into model crashes locally and found definite issues in maintaining signal even with the so called superior Spektrum radios. Just recently one local user landed his new high speed bird and complained that it appeared a little slow to respond at times. Upon inspection it was noted that he had 4 LOS occurrences in a 4 minute flight at a maximum distance of only 500metres. The light on a Spektrum Rx will flash once for each LOS experience it has from being powered up. (It is not how far it can work but rather the minimum distance at which it will always work)!

Definitely post your experiences but make them helpful towards reducing crashes or aircraft otherwise OUT OF CONTROL. Antenna setups and radios that caused issues or crashes should be posted so others can learn what not to do!

For instance the old favorite of interference, LOS issues experienced by DSM2 users at Flight Fest has been mentioned on the forum again this year and yet people continue to say how great DSM2 is! Even Spektrum has special warnings on the maximum number of DSM2 radios that can be operating at the same time in the same area and yet the warning and its reasons are not mentioned. People still use, (and recommend), DSM2 with its inherent weaknesses and problems!

Finally just a thought! Do not expect plane manufacturers or even radio manufacturers to take responsibility for a LOS induced crash! They make millions of dollars each year from us in replacement aircraft and aircraft parts due to poor quality radio communications. They will however improve their products IF we reject those products which are substandard or dangerous!

Have fun!
 

sprzout

Knower of useless information
Mentor
#23
Of late I have been looking into model crashes locally and found definite issues in maintaining signal even with the so called superior Spektrum radios. Just recently one local user landed his new high speed bird and complained that it appeared a little slow to respond at times. Upon inspection it was noted that he had 4 LOS occurrences in a 4 minute flight at a maximum distance of only 500metres. The light on a Spektrum Rx will flash once for each LOS experience it has from being powered up. (It is not how far it can work but rather the minimum distance at which it will always work)!

Definitely post your experiences but make them helpful towards reducing crashes or aircraft otherwise OUT OF CONTROL. Antenna setups and radios that caused issues or crashes should be posted so others can learn what not to do!

For instance the old favorite of interference, LOS issues experienced by DSM2 users at Flight Fest has been mentioned on the forum again this year and yet people continue to say how great DSM2 is! Even Spektrum has special warnings on the maximum number of DSM2 radios that can be operating at the same time in the same area and yet the warning and its reasons are not mentioned. People still use, (and recommend), DSM2 with its inherent weaknesses and problems!

Finally just a thought! Do not expect plane manufacturers or even radio manufacturers to take responsibility for a LOS induced crash! They make millions of dollars each year from us in replacement aircraft and aircraft parts due to poor quality radio communications. They will however improve their products IF we reject those products which are substandard or dangerous!

Have fun!
Hai, I understand where you're coming from, but DSM2 and DSMX are two different situations. DSM2 uses 2 channels for spectrum hopping, switching back and forth, setting it on startup. DSMX uses the full 2.4 GHz spectrum. You're right, DSM2 is an inferior product. That's why DSMX was created. Is it perfect? No. Neither is FrSky. It has its own inherent frequency issues. So does FlySky, Futaba, etc.

I hate to say it, but this seems to be turning into a "bash Spektrum" post. I get it if you don't like them, that's fine - that's your prerogative. Let's give people clear, concise reasons to buy into a particular protocol. Otherwise, we're becoming more and more of a "Apple vs. Android" fanboy base. Each one has its pros and cons, and each one is going to defend their choice to the end. I just know that most of the issues lately that you've targeted as loss of signal can also be attributed to other failures, such as ESCs getting hot, motors frying, even guys who forget to replace the batteries for their servos in a gas powered plane (we had that happen as a loss of signal at our field - the owner of the plane hadn't replaced the battery pack for the servos with a fresh battery, and his gas powered plane circled up and out of sight, to be found a week later at a local rancher's farm).

I think maybe we all need to be a little more agnostic on which transmitter brands we like. It's ok to post why we like them (for example, I like Spektrum because of its ease of setup, I can hook up a Horizon Hobbies BNF plane quickly and simply, and the voice commands that it calls out are great, TO ME), but I feel like we're getting into bashing choices, and I really don't want FliteTest to turn into the seedy side of RCGroups.

If you want to talk about a new technology coming in the near future, great. :) Talk it up - give us the points why you should choose it. But maybe we can leave the trash talking to the politicians, wrestlers, and professional sports players. :)
 

Hai-Lee

Old and Bold RC PILOT
#24
Hai, I understand where you're coming from, but DSM2 and DSMX are two different situations. DSM2 uses 2 channels for spectrum hopping, switching back and forth, setting it on startup. DSMX uses the full 2.4 GHz spectrum. You're right, DSM2 is an inferior product. That's why DSMX was created. Is it perfect? No. Neither is FrSky. It has its own inherent frequency issues. So does FlySky, Futaba, etc.

I hate to say it, but this seems to be turning into a "bash Spektrum" post. I get it if you don't like them, that's fine - that's your prerogative. Let's give people clear, concise reasons to buy into a particular protocol. Otherwise, we're becoming more and more of a "Apple vs. Android" fanboy base. Each one has its pros and cons, and each one is going to defend their choice to the end. I just know that most of the issues lately that you've targeted as loss of signal can also be attributed to other failures, such as ESCs getting hot, motors frying, even guys who forget to replace the batteries for their servos in a gas powered plane (we had that happen as a loss of signal at our field - the owner of the plane hadn't replaced the battery pack for the servos with a fresh battery, and his gas powered plane circled up and out of sight, to be found a week later at a local rancher's farm).

I think maybe we all need to be a little more agnostic on which transmitter brands we like. It's ok to post why we like them (for example, I like Spektrum because of its ease of setup, I can hook up a Horizon Hobbies BNF plane quickly and simply, and the voice commands that it calls out are great, TO ME), but I feel like we're getting into bashing choices, and I really don't want FliteTest to turn into the seedy side of RCGroups.

If you want to talk about a new technology coming in the near future, great. :) Talk it up - give us the points why you should choose it. But maybe we can leave the trash talking to the politicians, wrestlers, and professional sports players. :)
Sadly it is not Spektrum I have issue with but rather those who seem to gloss over the radio product issues and recommend the same old radios as being the best even though technology and product offerings improve over rather short time periods. I have observed blanket Spektrum recommendations being made without any clarification as to the limitations of their entry level products.

I have Spektrum, FlySky, FrSky, and a number of other supposedly superior radio systems and EVERY radio system has its issues and sadly most are rubbish for fixed wing aircraft! I also have a number of retired radio systems including 36 MHz analog types. In the past I have also used Sanwa and Futuba. Lately I have been collecting, (through owner donations), a range of radios that are wholly unsuitable for fixed wing aircraft some of which have never been used and are still in their original packaging! Most are gifted by grateful students who realize that the first radio they purchased, (on hobby shop recommendation), is useless for their needs!

Currently manufacturers make a range of radios to suit individual applications and needs BUT then allow their products to be marketed as suitable for all applications even though basic theory shows that they are totally ill-suited to at least some applications. I really do not care what the label on the front of the box/controller says as to who is the manufacturer but rather the performance of the system. If the thread appears to be a little Spektrum heavy perhaps it reflects the popularity of Spektrum currently and the large number of users/devotees the brand has!

At my local club there are three main brands in use with Spektrum having the majority of users. The club also uses Spektrum and Flysky as teaching platforms! I recommend some Spektrum and FlySky products and warn against others based upon their radio operation in relation to likelihood of a LOS occurring!

Spektrum, FrSky, FlySky and almost every other radio manufacturer have, (some), product offerings which are not suitable for maintaining communication with a fixed wing aircraft and yet there is NO indication as to the limitations of their entry level products with the EXCEPTION of Spektrum which does have a warning of user number limitations in relation to the operation of DSM2. Radio communications performance or communication issues are almost totally ignored!

If someone is injured or killed by an aircraft due to a LOS incident using a radio setup that you personally recommended, would you accept responsibility for your recommendation? I do not know if I would want to and so I want to help persons make the absolute best decision for their own safety and the safety of others.

Those who read my posts would know that I am a club committee member, a flight instructor, a plane designer, builder, repairer and I even do radio repairs. My growth in the local chapter of this hobby took off when I started to actually improve my own radio equipment and installation quality. During my early days I crashed everything I managed to get into the air. I started this whole push in informing others of the radio limitations as a result of studying model crashes, (Mine initially and later those of other club members), and becoming a flight instructor as well as my current desire to replace my latest radio system with one that will last me the remainder of my life or close thereto.

So far I have been watching the latest Spektrum, Flysky, FrSky, Jumper, Sanwa and even Futuba offerings to try and ascertain which is best suited in technology, support, features, cost, and ease of use! To date there has been NO superior radio found though a couple have made the short list, including Spektrum. Unfortunately some are still repeating the same old radio issues/problems over and over!

This thread could end up being a Spektrum, Jumper or FlySky recommendation but the jury is still out at this time!

I am sorry if you have been offended by my raising an issue or two with SOME spektrum products but rest assured there is a common issue across almost every radio manufacturer's product range in that they do not give a product suitability rating and many products are actually substandard for fixed wing RC usage. Currently my personal recommendations are FlySky for entry level and Spektrum for high end radios but this is subject to change without notification as new products are released and further developments in radio tech become available!

Have fun!
 

sprzout

Knower of useless information
Mentor
#25
Sadly it is not Spektrum I have issue with but rather those who seem to gloss over the radio product issues and recommend the same old radios as being the best even though technology and product offerings improve over rather short time periods. I have observed blanket Spektrum recommendations being made without any clarification as to the limitations of their entry level products.

I have Spektrum, FlySky, FrSky, and a number of other supposedly superior radio systems and EVERY radio system has its issues and sadly most are rubbish for fixed wing aircraft! I also have a number of retired radio systems including 36 MHz analog types. In the past I have also used Sanwa and Futuba. Lately I have been collecting, (through owner donations), a range of radios that are wholly unsuitable for fixed wing aircraft some of which have never been used and are still in their original packaging! Most are gifted by grateful students who realize that the first radio they purchased, (on hobby shop recommendation), is useless for their needs!

Currently manufacturers make a range of radios to suit individual applications and needs BUT then allow their products to be marketed as suitable for all applications even though basic theory shows that they are totally ill-suited to at least some applications. I really do not care what the label on the front of the box/controller says as to who is the manufacturer but rather the performance of the system. If the thread appears to be a little Spektrum heavy perhaps it reflects the popularity of Spektrum currently and the large number of users/devotees the brand has!

At my local club there are three main brands in use with Spektrum having the majority of users. The club also uses Spektrum and Flysky as teaching platforms! I recommend some Spektrum and FlySky products and warn against others based upon their radio operation in relation to likelihood of a LOS occurring!

Spektrum, FrSky, FlySky and almost every other radio manufacturer have, (some), product offerings which are not suitable for maintaining communication with a fixed wing aircraft and yet there is NO indication as to the limitations of their entry level products with the EXCEPTION of Spektrum which does have a warning of user number limitations in relation to the operation of DSM2. Radio communications performance or communication issues are almost totally ignored!

If someone is injured or killed by an aircraft due to a LOS incident using a radio setup that you personally recommended, would you accept responsibility for your recommendation? I do not know if I would want to and so I want to help persons make the absolute best decision for their own safety and the safety of others.

Those who read my posts would know that I am a club committee member, a flight instructor, a plane designer, builder, repairer and I even do radio repairs. My growth in the local chapter of this hobby took off when I started to actually improve my own radio equipment and installation quality. During my early days I crashed everything I managed to get into the air. I started this whole push in informing others of the radio limitations as a result of studying model crashes, (Mine initially and later those of other club members), and becoming a flight instructor as well as my current desire to replace my latest radio system with one that will last me the remainder of my life or close thereto.

So far I have been watching the latest Spektrum, Flysky, FrSky, Jumper, Sanwa and even Futuba offerings to try and ascertain which is best suited in technology, support, features, cost, and ease of use! To date there has been NO superior radio found though a couple have made the short list, including Spektrum. Unfortunately some are still repeating the same old radio issues/problems over and over!

This thread could end up being a Spektrum, Jumper or FlySky recommendation but the jury is still out at this time!

I am sorry if you have been offended by my raising an issue or two with SOME spektrum products but rest assured there is a common issue across almost every radio manufacturer's product range in that they do not give a product suitability rating and many products are actually substandard for fixed wing RC usage. Currently my personal recommendations are FlySky for entry level and Spektrum for high end radios but this is subject to change without notification as new products are released and further developments in radio tech become available!

Have fun!
I think it's time I walk away from the FliteTest forums for a while. It sounds like anyone who likes a particular brand is being considered a danger to the hobby.
 

Hai-Lee

Old and Bold RC PILOT
#26
I think it's time I walk away from the FliteTest forums for a while. It sounds like anyone who likes a particular brand is being considered a danger to the hobby.
Sadly that is not what I have said! I have said that almost every manufacturer makes some versions of their product that are unsuitable for reliable communication in fixed wing aircraft. The failing is that persons seem intent on associating their own preference for a radio brand as being suitable for every application. Some of almost every manufacturers product offerings are appropriate for terrestrial vehicles, (only), some for terrestrial vehicles and Quads, (only), and finally some for all applications including fixed wing aircraft! Sadly there is no apparent differentiation at the shop counter except the recommendations of the sales assistant or in our case the opinions and recommendations of fellow users! Spektrum radios are very good BUT not all Spektrum products are suitable for fixed wing aircraft!

For terrestrial vehicles a single antenna receiver and transmitter is sufficient, (regardless of brand). For Quads and the like a single antenna Tx or Rx combined with a dual antenna Rx or Tx is sufficient. For fixed wing aircraft a Dual Antenna Tx combined with a dual antenna Rx is minimum on the understanding that the Rx antennas can be located clear of all metal and wires. That is not brand specific but rather RF communication needs specific! To make recommendations based upon manufacturer brand alone or to recommend a single antenna radio Rx or Tx is what is actually dangerous.

Trying to have people see the differences in product performance of a manufacturers offerings at a RADIO level, (physical level), and hence suitability variations, seems to have upset some even when I have tried to point out that the issue is NOT brand specific! In a previous example, (the fly away), the radio Transmitter was a NEW Spektrum DX9, (dual antenna version), and it was NOT the issue but rather it was the Rx chosen which was purchased on price and protocol compatibility that was the real cause of the loss!

Ask mayan what difference a proper (dual antenna), radio system has made to his number of crashes and his development within the hobby, (I assure you his story is more the norm than an exception, though he did not give up as others have).

I again apologize if I have offended you or your brand loyalty as that was not my intention.

Have fun!
 

Piotrsko

Well-known member
#27
Sadly, most LHS owners are entrepreneurs and don't do what they sell. Oddly most hobbyists are EXTREMELY cost concious to the point of being ridiculous. Generally not a winning combination particularly when one is just starting out.

As I have said before, I dont agree with many of his answers, but I have seen that @Hai-Lee knows his business, and you will always get a properly informed answer.

Back in the DARK AGES, when I was starting out, radio "glitches" were common and got to be the reason for so many crashes, deservedly or not. Due to the unique way some of my older stuff responds to LOS, I can say with reasonable confidence that in 30+ years I have had ONLY 3 or 4 LOS incidents. The remainder can be attributed to either being stoopid or flying too close to the edges of the sky.

My $0.02 YMMV
 

Hai-Lee

Old and Bold RC PILOT
#28
Sadly, most LHS owners are entrepreneurs and don't do what they sell. Oddly most hobbyists are EXTREMELY cost concious to the point of being ridiculous. Generally not a winning combination particularly when one is just starting out.

As I have said before, I dont agree with many of his answers, but I have seen that @Hai-Lee knows his business, and you will always get a properly informed answer.

Back in the DARK AGES, when I was starting out, radio "glitches" were common and got to be the reason for so many crashes, deservedly or not. Due to the unique way some of my older stuff responds to LOS, I can say with reasonable confidence that in 30+ years I have had ONLY 3 or 4 LOS incidents. The remainder can be attributed to either being stoopid or flying too close to the edges of the sky.

My $0.02 YMMV
Sadly I wish my luck had been as good. On my return to the hobby it had all changed and my radio setup was suddenly considered as dangerous so I looked for a cheap radio system. Well I definitely got a cheap one even though it was recommended and many had claimed it had great performance for them. All it did for me was to create a huge pile of destroyed models. The radio always seemed to survive and it is still going strong though I do not use it any longer.

I also am partial to doing some crazy things and checking out the edge of the sky BUT the difference is that now I have a much increased chance of saving the model and bringing it back to fly another day!

A different entry level radio system, (less than $10 AUD more in price, delivered, purchased off of the internet), which was more suited to my requirements made a MASSIVE difference. How many others have been sucked into buying an unsuitable radio, (by a hobby shop or other recommendation), and paid the price in aircraft damage and replacement parts and even possibly left the hobby because they thought that they would never be able to fly?

One is too many and I am sure that there is a very large number of such victims scattered around the globe!

May have some real news in the near future on this matter!

Until then,

Have fun!
 

Hai-Lee

Old and Bold RC PILOT
#29
After recent events I did some further research and stumbled on what SPEKTRUM recommends as best practice in relation to antenna positioning which you can read for yourself if you go to https://www.spektrumrc.com/Experience/InstallationBestPractices.aspx

Whilst it is all good information it also does show that my seeking a three antenna system is not some ramblings of an old man but is also recommended by Spektrum on the same page under "Do POLARIZE YOUR ANTENNAS". Here is what it says!

DO POLARIZE YOUR ANTENNAS
Polarization is simple: it means putting the antennas in vertical, horizontal and longitudinal axis (X,Y,Z, to some).
What this does is assures that at any time, one receiver will be oriented for optimal polarization. This also contributes to why you should use three receivers (or four) whenever possible.
Polarization isn't absolutely critical, but it sure helps to give lower numbers (a stronger link). The results can be seen on the Flight Log.


Please read and do your own self assessment of what is best for you and your aircraft as well as if your current radio is adequate for your fixed wing models!

Have fun!
 

Merv

Well-known member
#30
Virtually all radio problems can be traced back to improper antenna placement or antenna damage.

Foam and dry wood are essentially invisible to RF. Metal, carbon fiber, electronics and anything wet (trees with leaves, fog, rain) will block RF. If your put your active element right beside your carbon fiber spar, ESC or battery, you are asking for trouble. If your antenna lead is damaged, you will kill your range. If you put a 90 degree bend in the active element, you will cut your range. Keep the active element of the antennas relative straight and away from things that block the signal.

All brands of the equipment we have today are capable of ranges far beyond what can be controlled by line of sight. All brands will fail if you don't install them correctly or if they become damaged.
 
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Hai-Lee

Old and Bold RC PILOT
#31
Virtually all radio problems can be traced back to improper antenna placement or antenna damage.

Foam and dry wood are essentially invisible to RF. Metal, carbon fiber, electronics and anything wet (trees with leaves, fog, rain) will block RF. If your put your active element right beside your carbon fiber spar, ESC or battery, you are asking for trouble. If your antenna lead is damaged you will kill your range. If you put a 90 degree bend in the active element, you will cut your range. Keep the active element of the antennas relative straight and away from things that block the signal.

All brands of the equipment we have today are capable of ranges far beyond what can be controlled by line of sight. All brands will fail if you don't install them correctly or if they become damaged.
You are correct in all you say but it is not the maximum range you can achieve but rather the minimum range at which you can guarantee reliable communication that is what I am warning of.

If you use a single Antenna radio system and fly a reasonable distance away you can still have good control BUT cause the Tx/Rx, antennas to work at right angles to each other, (wrong polarization), or even have the antennas actually pointing at each other and the signal drops so low that the radio system may not be able to maintain communications at all. In a worse case scenario there can be zero communication or signal Rx'ed at all.

Whilst I have not until now touched on interference my own tests and examinations have proved, (to me), that the majority of claimed interference problems are actually poor setup related! Two actual tests I undertook using first my own aircraft and reworking the antenna layout and Rx choice for one of our young club members showed how easily interference is blamed for way more than it actually causes.

Firstly one of our experienced pilots complained that he was struggling for control in one corner of our field, (the same corner where he always seems to have "interference" issues though not every flight). After he landed he showed the Rx light flashing which indicated a LOS condition which he promptly blamed on interference, So I took off in one of my planes, (fitted with a dual antenna radio setup), and I stunted in the very area where he was claiming there was interference. Watching my antics he fitted a fresh battery and he was again flying the patterns he was previously. Yet again he was struggling for control in the very area where I was looping, rolling, doing Stall turns and the like without a hiccup! After we both had landed he again showed the flashing Rx light and continued to blame a source of interference.

In the same area a few weeks later one of our young pilots was also complaining of the same interference. I asked if I could look at his setup and he had a dodgy dual short antenna Rx buried deep within the wiring of his plane. I asked if he had any other Rxs and he said that he still had the Rx I had repaired the antenna on a few weeks prior. It had long wire antennas and so I fitted the repaired and untested Rx as per what antenna theory and Spektrum recommend. On his next flight he tried hard to linger in the "Interference" and even resorted to doing some rather severe aerobatics as well. On landing a check of his Rx showed that he had experienced ZERO LOS events and of course the dreaded interference had suddenly disappeared, (well for him, me, and about half of the club members as some others were still experiencing it and are still to be convinced about the quality of their equipment and setup)!

Generally speaking, if there is interference effecting an area it should at least be effecting all radios of the same type in the same area at the same time as interference is a radiated signal! If only a small number of users are experiencing the issue when others with the same gear are not then, seriously, interference should be discounted. I have not found any transmitted radio interfering signal that is user specific as it is almost always area specific! True interference should effect all that enter the effected area and not a selected number!

Have fun!
 

Piotrsko

Well-known member
#32
ABOVE last paragraph needs to be in BOLD font, possibly with flashing arrows and someone screaming on the street corner: "pay attention people!"

What part of "dodgy short antenna" did you make longer? I am guessing the coax portion not the active element so that you could position it better.
 

Hai-Lee

Old and Bold RC PILOT
#33
ABOVE last paragraph needs to be in BOLD font, possibly with flashing arrows and someone screaming on the street corner: "pay attention people!"

What part of "dodgy short antenna" did you make longer? I am guessing the coax portion not the active element so that you could position it better.
The antenna repair has a story in itself. Apparently the owner had ripped the antenna lead off of his AS3X Rx which had a pigtail antenna soldered to a small board which in turn was connected via coax back the the main Rx housing. He had not asked for any repair as I may very well have been busy in a training session with my students.

Anyway he took the damaged Rx to the local hobby shop and asked if they could arrange to have it fixed. He was told that it was irreparable and they tried to get him to buy a new replacement. The cost was WAY WAY beyond his budget so he bought a cheap short antenna plain Rx and from the beginning he was struggling flying with it.

It was a couple of weeks later when he seemed to be struggling in the wind and upon my seeing the AS3X labels on the plane I made a comment that obviously the AS3X was not set up correctly. It was then he relayed his story and showed me the damaged Rx. I informed him I would attempt to repair it on the understanding that I would not be able to test the repair beyond a simple range test and he would need to undertake the testing of the effectiveness of the repair.

When I returned the Rx to him he quickly placed it in his flight box and there it stayed until the day as mentioned previously. The repair was simply a matter of removing the heatshrink from the amp board, fit a new antenna whip, and then supply and fit a new heatshrink cover for the amp PCB. (Of course the wire was trimmed to the appropriate/original length).

As a side note since sorting out his antenna placement and the need for care in gear selection he has been gifted a number of my excess planes because at least he knows now what to look for in setup.

Have fun!
 

Piotrsko

Well-known member
#34
So in essence you aquired a piece of Mil-C-17/(124) [my dash number could be off, been a while] and soldered it in place of the old?

By any chance do you know what type feed these are (gamma, delta, etc) or the impedance? They don't look like a Marconi, although theory says the air gap could be at either end which would make mounting simple and rugged. Could be a clipped dipole, come to think of it.
 

Hai-Lee

Old and Bold RC PILOT
#35
So in essence you aquired a piece of Mil-C-17/(124) [my dash number could be off, been a while] and soldered it in place of the old?

By any chance do you know what type feed these are (gamma, delta, etc) or the impedance? They don't look like a Marconi, although theory says the air gap could be at either end which would make mounting simple and rugged. Could be a clipped dipole, come to think of it.
I did not bother to look too hard at the board but I did inspect the broken antenna wire before I replaced it, (to try and match the radiator material but it was little more that a piece of multi-strand tinned copper wire, (ordinary hook up wire)). I matched the diameter etc, to maintain the radiation resistance, (best as), but seriously I was a little surprised at the overall quality,

After all I suppose it is only a commercial grade product. I doubt that they are even checked for actual performance or tuning at manufacture but rather are cut by machine and soldered by hand. (a case of close enough is good enough for a Rx). Transmit antennas are normally proper end-fed coax dipoles but I cannot guarantee that their performance is checked accurately either!

FYI Have been in touch with one of the manufacturers in relation to a 3 antenna system for receivers and they seem interested! Was even asked to explain the theory and the added benefits for their product which I did in detail, and so I am waiting on their next response to see if they are serious in pushing it further, or considering its implementation! MAYBE we might get an airworthy radio system yet at a reasonable price!

Have fun!
 

Bricks

Well-known member
#36
I have added antenna length to a few of my cheap Orange receivers using thin coaxial cable and soldering it to the board. The cable I got is a little stiffer and thicker then I wanted but it has worked well now I can use any length of antenna I need just cut strip the very end for correct length and solder.. Being the wire is a little stiffer I will add a dab of glue at the solder junction.
 

L Edge

Well-known member
#37
Comments on LOS:

Why do pilots buy one radio brand and buy cheap knockoffs for their RX's? Remember the knock offs can't duplicate the orginal, so it's minus on the design(SO THAT THEY ARE NOT SUED). That will cause some los due to inability to match all conditions that were tested. Point being, buy the company's matching equipment.

Range tests: I doubt many pilots do not Range Check their airplane. Being a member of three clubs, I very seldom anybody go thru the paces of range checking befor they fly. Do you run the motor(s)/prop to see if no problems exist? How about after a crash? LOS is possible. If unsure, walk around the plane to see if los happens. When we pylon raced, we would walk around 360 degrees doing the range check with engine on so los isn't present.

Did you know the better radios have ways of using telemetry and meters hook to the rx to count fades,etc per flight.? In many cases, the problem is location of the rx and it's direction of antenna(s). Having a composite plane, it paid off for I got los range checking, I had the correct direction of antennas, but wrond distance from the motor. Change the distance of one of the satelite antennas to 36 inches away, problem went away. Check with your product support on how to set it up properly.

So, do a range check every so often to insure flying safety.
 

Hai-Lee

Old and Bold RC PILOT
#38
Comments on LOS:

Why do pilots buy one radio brand and buy cheap knockoffs for their RX's? Remember the knock offs can't duplicate the orginal, so it's minus on the design(SO THAT THEY ARE NOT SUED). That will cause some los due to inability to match all conditions that were tested. Point being, buy the company's matching equipment.

Range tests: I doubt many pilots do not Range Check their airplane. Being a member of three clubs, I very seldom anybody go thru the paces of range checking befor they fly. Do you run the motor(s)/prop to see if no problems exist? How about after a crash? LOS is possible. If unsure, walk around the plane to see if los happens. When we pylon raced, we would walk around 360 degrees doing the range check with engine on so los isn't present.

Did you know the better radios have ways of using telemetry and meters hook to the rx to count fades,etc per flight.? In many cases, the problem is location of the rx and it's direction of antenna(s). Having a composite plane, it paid off for I got los range checking, I had the correct direction of antennas, but wrond distance from the motor. Change the distance of one of the satelite antennas to 36 inches away, problem went away. Check with your product support on how to set it up properly.

So, do a range check every so often to insure flying safety.
You are quite correct BUT a range test on the ground can only prove that at least one antenna is functioning and that you were in a position where the signal was not obstructed! Based upon that knowledge you can see that ideally a true radio range test should be rather elaborate and involve the range test being done a full 360 degrees around the plane as well as with the plane in all possible attitudes to the transmitter that the plane would achieve in flight, (The flight battery could be flat by the time such a comprehensive range test was accomplished)!

A better range test approach would be for the range test to cause the Tx to select one of its antennas only and for the Rx to cycle between Satellite receivers or diversity antennas and report back to the transmitter the signal levels. Then the Tx swap its antenna and for the Rx to cycle through its antenna a second time with the values returned to the Transmitter. The results could be noted and then the pilot would go to another point with a different view of the plane and repeat the range test. If done three times around the plane at least you would find any blocked or faulty antennas before you fly to maximum range and experience a LOS.

The cheap "Knockoffs" are not always inferior! Some of the so called Knockoffs have licensed use of the same air protocols or even chjpsets as some of the manufacturers genuine product. Not all manufacturers have ownership of, or exclusive rights to the on air protocol they use.

Generally the greater the number of knockoff products the less exclusive the protocol actually is. In one particular instance where a manufacturer's product becomes to expensive for the protocol owner, the owner has contracted other manufacturers to use their protocol to make lower cost equipment, (even though the cheaper products are distinctly inferior in most important aspects), to try to attempt to maintain market share rather than to provide a quality product.

Your use of Satellite Rxs shows that you are definitely among those who know what to do and even how important it is to get it right. Sadly this is not the case for a lot of other users, especially newbies and the like. My only complaint about the use of satellite antennas is their cost which makes their ready adoption by newbies to fixed wing RC model aircraft extremely rare. There is nothing cheap about a cheap receiver or radio system because what you do not pay for the radio you end up spending on repairs and replacement aircraft. The longer you persist with a cheap radio system the greater the cost!

Thank you for your interest in the topic!

Have fun!
 

Hai-Lee

Old and Bold RC PILOT
#39
About a week ago I was asked to provide a primer on the issues with antenna placement and the current generation of RC radio control systems. Since then I have been busy with RC equipment manufacturers and the like pressing the point and most agree about the issue but are happy to continue with the status Quo for the time being. (I can assure you that it will not always remain as it currently is!

Any way I spent days plotting LOS locations and ray tracing only to find that the pretty graphics soon became so congested that even I had trouble reading them. So I decided to do a spread sheet with Tx and Rx antenna numbers and their polarity in use and then where a LOS can be expected to occur.

For the spreadsheet the Vertical antenna position is true vertical, The horizontal antenna is mounted across the fuselage parallel with the fuselage bottom and the "Z" or third antenna is horizontal along the bottom of the fuselage. If your antenna placement is different then the only real difference it the attitude of the plane when it happens!

The plane is assumed to be RF transparent with no antenna obstructions and there are no reflected ray paths from the Tx antennas. Whilst some reflections do occur in the real world and there are antenna obstructions in a real plane the spread sheet at least gives a rough guide as to the area you could expect a possible LOS, Brown out, or interference episode!

Keeping the plane in close proximity to the Tx will reduce the effects but the points mentioned are definitely minimum or NO radio signal spots.

Here is the info:-
LOS Points.jpg
I will get back to it later to check my work and add points I currently have missed!

Have a read and do your own comparison with your own experiences!

Have fun!
 

Piotrsko

Well-known member
#40
Really Nice work. I would like to see your LOS plots just for my education. I bet the graph has colors and patterns ad nauseum.. (joke follows) probably a null area just above the only big rock in the entire field, too, or just before the trees. Based on the complaints I have heard form others, probably right at the end of the runway also.

I see you have justified your 3 antenna as having no LOS.

Any defination in the data regarding high end named equipment? Futaba, Graupner, expensive Spectrum, or do they all perform similair? I only ask since, to my awareness, I haven't had an issue with my 6ex Fasst system, however that might only be due to my knowledge of antenna systems.
 
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