Which Receivers does Tony's Flywire work well with?

[planekrazy]

I have used Tony's inductor trick on my GWS 4P rx and it works great. I'm looking to use it with other receivers that i have but don't know which ones it will work well with.

I have the following receivers and need to know which ones are safe to use with Tony's flywire method:

- Hitec 555
- FMA Extreme 5
- Berg 5
- JR 610 (new ones)

Btw, just for reference, Tony's flywire web page is here: http://www.uoguelph.ca/~antoon/gadgets/flywire.htm

Thanks in advance,
Mehrdad

[vintage1]

I guess there is only one way to find out. :)

That choke plus whip replaces electrically a given length of antenna wire.

So if a given RX has the same antenna length as one that works, then it should work as well.

Don't trust me tho, do a range check!

It may match electrically, but its a bit smaller, so range is always going to be affected.

[planekrazy]

Originally posted by vintage1
I guess there is only one way to find out. :)
....

The only way i'm going to find is by hearing from someone who's tried it and knows it works.... and is willing to share the information ;)

Knowing that even a small number of folks are using the inductor with a given rx and that they find it works well would be a great data point (i have not been able to find a single concise thread on this topic on Ezone....lots of incomplete info spread over many posts).

Btw, I expect range to will be less after shortening the original antenna -- i just don't want new type of glitching issues to arise as result of using the inductor with the wrong type of Receiver. Frankly, i'm not sure if rx with base loaded antennas are known to work or not with Tony's Flywire method.... and if that is true, then which receivers use base-loaded antennas? Help :o

FYI: a suggestion from a buddy to use the inductor with GWS 4P actually reduced glitching (when flying over other pilots tx), which was more than i could ask for with a $20 rx. So Tony's Flywire mated to the GWS 4P has really worked for many of us at the field.

I never have had glitching problems when flying over pilots tx using a stock JR 610, Berg 5, FMA Extreme 5 or Hitec 555 rx. But i do need to shorten their antennas for various projects and having reduced range is not an issue for me. The issue for me that i really like the inductor price over the Azzarr unit ($.35 vs $10), but don't know which receivers i can use it with safely (i don't want to experience new glitch issues as a result of the added antenna).

Note: When the field is busy, i have had some minor glitches with the stock JR 610 -- very momentary and at very specific areas so they were/are somewhat perdictable. I decided to shorten the antenna on the JR 610 using the Azzarr unit which works fine. Of course, it didn't get rid of the minor glitches (nor did it add new glitch issues). The minor glitching is still there on busy days, but no more dandling antenna :)

Also, given that i've seen range checks pass on the ground, then when the model is in the air it goes out of control because of increased to suspectibility to 3IM or too much signal power, or i don't know something else.... whatever, i don't really care as long as i can avoid it by using the method in known to work for others.

[kasra]

Hi Mehrdad,

I have used the flywire on 555 and the Berg 5. I don't think the Extreme and other FMA receivers will work with it. I use Azarr's for those. I don't know about the JR 610.

Kasra

[RMihara]

Hi Kasra, Mehrdad,

Apparently the Berg 5 can be run with it's antenna cut down to less than 9 inches, this places it very close with Tony's base load scheme without the baseload so perhaps that is why it works?

Haven't bothered with FMA stuff since going to the Berg.

Roger

[planekrazy]

Thanks guys :)

I was hoping to be able to use the FMA Extreme 5 in the Sokol with the inductor antenna (since i have inductors but no the Azzarr antenna). So i guess i'll use the Hitec 555 with the inductor given that it sounds very safe....just that the Sokol is already really (really) kinda heavy :o

[vintage1]

Look, recievers antennas really are not that critical.

If you cut them short, two things happen..

(i) they pick up less signal

(ii) Their resonant frequency and impedance at the wanted frequency changes. (two aspects of the same thing).

Common sense dictates that since antenna installation is well outside the limits of what a designer can design for, rx antennas are NOT highly tuned entities, and so are very tolerant of being messed around with.

What that inductor does, is match the inductance of the bit of wire you have replaced it with. So in theory no matter how the receiver is constructed, it should work the same.

If you are getting better interference rejection, my guess is that the choke is doing a better job of keeping harmonics out of the reciever than the antenna, and that is interesting, and useful.

My conclusion is that if that choke works to replace 'x' inches of antenna in one design, it will work in all designs. The receiver can't 'see' any different - at least at the normal frequencies. Out of band its a slightly different story though.

That's all in theory, and it sounds like you have a healthy disrespect for theory, which is cool. Theory is only as good as far as it goes. If you miss something in your analysis theory is a heap of wombat t*rds...so thats why I said that the only true test is to try it.

Let's face it, if it doesn't work, solder the antenna back together, and nothing is lost.

In theory, it should work on all receivers as far as I can see, unless there is something in it that e.g. makes the receiver do weird things at some other completely different frequency.

Over here we fly on 35Mhz, and I am very interested in this as a quick and dirty way of gettiong a tad more range out of small receivers.

[GregG]

Brian Chan has been making and flying his own version of this antenna for quite some time. As a matter of fact, I've seen him fly his Sokol with the antenna in a N.Cal pylon meet we had last year. When I asked him for plans he gave me the same webpage. Perhaps we can get him to comment here.

[bhchan]

Mehrdad,
The rx I have use with the fly wire:

Hitec 535, 555, Superslim8,

Berg6 with some problem, I have 4 rx, 3 works and one didnot(????)

You can also replace the stock antenna with the smallest piano wire of the same length to reduce the weight and ugliness, the small wire also invisable to human eye but the electron can "see" it.;)

And you can always get the antenna from me....:D


Brian, an EAJ.

[planekrazy]

Big thanks to everyone helping me on this :)

Vintage1, i very much appreciate the background info and theory of operation you provided. I too would presume the addition of an inductor would have the same effect on all receiver designs -- i'm only questioning the theory because i had heard some flyers experienced problems using the inductor (shorten antenna) with an FMA Extreme 5 rx. I would be very interested in understanding why this combo may not work. Without hearing some success stories, I'm too chicken to try it on my brand new FMA Extreme 5 rx, in my brand new/never flown Sokol (that is very heavy and expected to be very fast....the last thing i want to worry about on the maiden launch would be glitching due to a new rx/shortened antenna combo...and i'm too lazy to test the setup in a different (more tame) model :p

It would be nice to understand more why the FMA Extreme and inductor setup may not work.... or from folks who have tried it and found that it works just as good as adding the inductor to say a Hitec 555. Originally posted by kasra
...I don't think the Extreme and other FMA receivers will work with it.... Kasra, do you recall where you heard that? Or did you personally run into a problem with it?

[kasra]

Hi Mehrdad, I experienced it with a FMA Tetra when I used Dean's. Ron Fikes told me about the FMA's having a tuned front end and not responding to the inductor. In my Sokol and Switchblade I used the Extreme with Azarr's. I have an extra Azarr antenna if that means we can get to see the Sokol fly this weekend. I am looking forward to it.

Kasra

[planekrazy]

Brian, thanks for your kind offer.... all of this time here in the bay area and i'd never visited Halted before :eek: Imagine that :o
Anyways, i was bored at work the other day so i dropped by Halted to check out the place and get in on the cheap inductor action :cool: I'm set as far as inductors go for a while :D

[planekrazy]

Thanks Kasra, you're awesome...i just may take you up on that offer. Although i'm still curious how the inductor messes with the tuned front end on the FMA rx.

Also, is the same front end used by the FMA rx, in other words, how about using the inductor with the new FMA M5 rx?

[planekrazy]

Perhaps Mr. Fred Marks can share his thoughts regarding using Tony's Flywire (inductor-based antenna shortening) technique on FMA receivers such as M5, Extreme 5, Quantam 6, etc. Will PM him a link to this thread...hopefully he still has time to answer non-Kokam questions ;)

[Neil Morse]

Mehrdad:

Like Brian, I have used the flywire with Hitec 535, 555, and super slim. I have noticed no reduction in range at all. I had my Wingo up over 1200 feet with no problem.

Neil

[RMihara]

Vintage1, if it weren't for some 'healthy disrespect for theory' we wouldn't learn anything new would we? :)

Hi Mehrdad, I don't have a good RF background nor in antenna design but I recal seeing a thread once mentioning 1/4 wave, 1/8 wave relationships to the Flywire (and/or any base load antenna design). Has to do with sampling only a portion of a full signal wave which is why transmission/reception performance becomes limited.

Makes me think that a 'tuned' front end receiver expects to see a full signal wave and not a portion of it, maybe that's why certain receivers balk at this base load antenna scheme.

'Heavy Sokol'? Mehrdad what are you up to? :D

Ended up at RSA late this afternoon. Heard there was another Sokol rippin-it-up at Baylands...torque rolling on launch :eek:

Hi Neil, I think you must've had some conductive fog working to your advantage that day! :D

Roger

[Mr.RC-CAM]

My theory on why the inductor reduced glitching, per one of the previous comments, is because it offered a less than ideal antenna match and reduced its front end sensitivity (via reduced received signal strength). In fact, GWS users often cut the stock antenna in half (to 18" or so) to prevent glitches. It is really a stretch to think that the inductor acted as a filter.

Also, on the Rx's that experienced glitches after adding the flywire, I would suggest it is because their designs had less native sensitivity. The lossy inductor hack dug too deep into the "Rx gain budget."

There is soooo much extra gain margin in a modern R/C Rx that we can really dork up the signal strength before we notice anything. The trick is to not go too far, or you (and your model) will feel the impact. ;)

Lastly, no matter how perfect a reduced length base loaded R/C antenna design is, it will reduce signal strength by several dB. With the overall lengths that most of them use, expect -5dB minimum. That amounts to signal reduction of at least 50%, but only impacts range by about 25%. On the less than perfect designs, the range reduction is what ever it is.

Regards,
Mr. RC-CAM
www.rc-cam.com

[planekrazy]

Thanks Neil, Roger, Mr. RC-CAM -- Thanks alot for the info guys :)

Roger, i think the Sokol you heard about that day was David Hsu's; rippin' up the RSA sky. Btw, I finally got my Sokol done, i flew it once yesterday and a few times today... All went well thanks to Dave and Kasra to being there and sharing their wisdom with me.

Anyways, I ended up using the Flywire method along with a Hitec 555 and the radio gear has worked flawlessly -- knock on wood ;)

Hope to see you at RSA tomorrow.

Mr. RC-CAM, thanks again for the info. What you mentioned about GWS 4p+flywire being less glitchy (same as cutting the antenna length) is sure true as far as i've experienced, great combo. Regarding the cases where some receivers experience glitches after adding flywire (where the inductor may dig too deep into the "Rx gain budget"), would using a different value inductor possibly improve the situation?

Thanks to everyone for all of this great information.
Regards,
Mehrdad

[kasra]

What wisdom, but thanks anyways. Your Sokol is sweet as is David's.

I would like to retract that comment about the "tuned front end". I talked to Ron again and he said the FMA Tetra had the base loading built in (watch me get in trouble again.)

Now I really wish Mr. Fred Marks and perhaps Mr. Berg would pitch in...

Kasra

[Mr.RC-CAM]

would using a different value inductor possibly improve the situation? Yes, it will help if the existing value is not optimized. But just as important as inductance is the inductor's Q-factor spec.

I have a feeling that no two Flywire antennas are the same when built using different brands of inductors. Even if they use the "same" inductor uH value, the Q values can range all over the map.

When it comes to Q, most catalog purchased inductors offer poor choices and hand made RF inductors are usually better. You need an inductor with a High Q (aim for 200 or higher at 72Mhz). If the Q is poor, the antenna performance will be compromised, so do not ignore this little gotcha.

Sorry, but I cannot suggest any catalog parts -- just dig deeper into their specs and you will find the info.

Regards,
Mr. RC-CAM

[Tim2000]

planekrazy;

i got 3 flywires from brian and used on my planes

1/ my tiger moth with that cheapo GWS 4 channel RX:
not a single glitch for few hundreds of flight: oh yeah i got
many fingered glitches though

2/ my zero with more than 500 flights: not a single glich with the
cheapo GWS 6 channel RX; still some fingerd glitches

3/ my mirage 2000: it drove me crazy with the 555 rx:
the reason is i hide the flywire horizontally in the wing, while
on the moth and the zero it is raised 70 degree from the fuse.
So i now have 2 flywires on my mirage: 1 unused in the wing
and other raised 70 degree from the fuse connected to the
555 RX... troublefree since

[planekrazy]

Kasra,

Gotcha, so Ron had the problem on older the FMA Tetra. On the FMA website the spec pages for the Fortress 2000 Standard Universal rx and the Fortress Micro rx the following is stated: "All FMA receivers use 50 ohms impedance match throughout. When using the receiver on small models or surface models, the antenna can be cut to a length as short as 18 inches without de-tuning the receiver."
But this text isn't on the spec page of the FMA Extreme 5, M-5, Quantum nor Magnum receivers... i really wish Mr. Fred Marks would chime in. I think lots of folks would appreciate a nice cheap ($0.35) and light (1 gram) solution to the newer FMA receivers, like is possible with the Hitec 555, Berg, GWS, etc.. I know i had a hard time buying an Azarr M72 direct at $10 a pop, and with FMA selling the antennas for like $19.95....i had to sit down when i realized an M5 rx plus xtal and Azarr M72 from FMA would set me back over $100...and that didn't including shipping :eek:


Mr. RC-CAM,

Thanks again for all of the info, i'm still trying to digest it :) I'm feel so over my head i really wish i understood radio technology. I know nothing about Q factor nor how to best choose inductor values. Nor what type of equipment would be needed to figure all of this out... but just to prove how big of an idiot i am, i'm gonna ask -- if an inductor with high Q value was used, would the of painowire need to be lengthen (or shorten) from the normal 6 inch length recommended by Tony's Flywire method? :confused: of course :D


Tim2000,

Thanks alot for the feedback. So its clear that the GWS and Hitec receivers work well with Tony's Flywire. I experienced the same glitch issue/solution as you encountered with your Hitec 555 and Flywire -- with both the Azarr attached to a JR 610 rx in my RR and the Flywire attached to the GWS R-4P in the Moth. In both cases i would get glitch/gitter while on the ground, until the antennas were reposition such that they were not parallel to the two metal pushrods that run through both the RR's and Moth's fusealge. 20-30 degrees seems to be all it took. And the Hitec 555 and Flywire in the Sokol flew again today, and again no not a single glitch. I like the Hitec 555 and trust that the Hitec Electron 6 will work well with the Flywire as well.

Best regards,
Mehrdad

[rpage53]

On FMA's support page they tell you that you can just cut the antenna to a shorter length on their receivers. The impedance of the flywire is wrong for them. Flywires work on every other brand I've tried (Hitec, Airtronics, GWS).

A shortened loaded antenna has a narrower bandwidth than the original 1/4 wave whip. So you get less gain and better interference rejection on the GWS receiver. Of course, you'd have to tune the antenna to get the full benefit. Most guys just cut a hunk of wire and fly. If it passes your range check, tuning doesn't matter.

Rick.

[Mr.RC-CAM]

if an inductor with high Q value was used, would the of painowire need to be lengthen (or shorten) from the normal 6 inch length recommended by Tony's Flywire method?Assuming that the Flywire inductor value is correct, then the aerial length remains the same. The Q value only indicates if the chosen inductor's construction will work well at the operating frequency. Some inductors are for audio use, some for low freq RF, and so on. Just review the inductor's data sheet and look at its Q spec at 72Mhz. It is that easy.

RC-CAM

[kasra]

Originally posted by planekrazy
... and trust that the Hitec Electron 6 will work well with the Flywire as well...

Mehrdad, Just a couple of more data points. I have the 555 with the flywire in the Stinger and the SuperCub and ML3D today were both flying with the Electron 6 with the Flywire.

Kasra

[planekrazy]

Kasra thanks for confirming the Electron 6 RXs work well with the flywire method also.

Here's the response i got from Mr. Fred Mark regarding the 50 ohm impedance used on their receivers:

Dear Mehrdad,
FMA follows proper,professional electronic engineering practice. All our receivers are designed with a 50 ohm impedance match between stages and mixer inputs/outputs. This includes the antanna. This makes the receiver fasr less suceptible to mismatch when one uses a different antenna length or you hang several feet of servo lead onto the receiver. It also means that you can attach an Azaar antenna that is designed for a 50 ohm impedance to any FMA receiver and not detune the receiver. If you use other than the 39.5 inch antenna that comes on, say, a Hitec 555, you really should tune the receiver to that antenna as one has no idea what the impedance of the antenna or the receiver front end is.
best regards,
Fred

So now i'm wondering if i cut the Extreme 5's antenna to half its stock length (and do nothing else), how much range would that leave me with? Would i get 1200 feet of range with that setup?

[Mr.RC-CAM]

...i'm wondering if i cut the Extreme 5's antenna to half its stock length (and do nothing else), how much range would that leave me with?

In a perfect world, cutting the antenna in half will introduce a -3dB signal loss. On its own, this affects range by about 25%.

Although this will not "detune" the front end of the Rx (per FMA's comments), it does introduce a worse antenna-to-Rx impedance match. At 72Mhz, a 39" - 41" antenna is about 37 ohms, which is a reasonable match to the Rx's 50 ohms (good VSWR's). However, when you cut it in half, the antenna impedance falls. So the match is affected, which will further reduce the antenna's efficiency.

Final answer: "Before and after" ground range testing will tell you all you need to know.

Regards,
Mr. RC-CAM

[bhchan]

Tim2000

I use the same antenna on my Mirage 200 , sticks it into the wing from inside the fuselage, with no problem of glitching. I cut the loop off the tip so it will go through the foam easier.

Brian. an EAJ