hitec antennae bobbin anygood?

[juantrinidad]

i just bought an electron 6. it came with an antennae bobbin. a small plastic bow spool that you can spin 18 inches of antennae wire on. that much antennae 1.5 inch will allow me to keep the rx antennae within the fuse.

should i use it? how much range will i lose with it? anyone have experience with it?

JT

[vintage1]

I am going to sit back and watch the fun here. For some reason this question divides the camp into vituperative factions...

[U2Steve]

They give you the same thing with the Feather Rx. I've tried it with my Feather, and it's OK indoors, but I found it reduced range to under 200 yards outside. Make sure you wind it properly- no overlapping wire. Use a bit of clear tape to hold things together after winding.
On the other hand, the Azarr or Deans antenna replacements do better, are purpose-built for the job (of eliminating trailing wires) and are pretty cheap.

Vigorously and vehemently avoiding vituperatives,

Steve

[vintage1]

On the same subject, I stickl a Jeti REX4 0 had it about a year -in my latest model and with the antenna down inside the house its buzzin and twitchin at ten feet range!

Goes mad at about 15 and its out by 20


Is this normal?> and if so how much range is that in the air.

No, its not the motor. I left that disarmed whilst I tested.

[U2Steve]

Normal? No. But did you have any other electronics, or a noisy flourescent light, going nearby? Did the wire run next to metal or carbon control rods or structural members? Stuff like that can give you the twitches (never mind the plane)!

[vintage1]

Originally posted by U2Steve
Normal? No. But did you have any other electronics, or a noisy flourescent light, going nearby? Did the wire run next to metal or carbon control rods or structural members? Stuff like that can give you the twitches (never mind the plane)!

This computer in the next room...the house is covered in rendered wire mesh, so its weird around it, but normally I get about as far as the bedroom before I can hear twitches...


No metal at all in this model ! apart from two very thin snake inners...antenna is routed out inside the wing - about 18" of it (thats all there is) Someehat parallel to one aileron servo lead but an inch or two away.


There is a strange source of interference round these parts tho...think it may be a taxi Xmitter.


If I take it outside, assuming it *ever* stops raining...how much ground range with down anntenna - how much with up?

Last time I did this 'for real' I think my buddy and I got about 60m with the antenna down, tho motor interference was getting a bit prominent at that range. Flew fine to limits of visibility.


Futaba FF6 on 35Mhz TX.

I don't seem to have motor interfernce, as much as plain rotten all over sensitivity. I know this isn';t a full range reciever, but will it do 500m? I need that much to be safe really...

[tim hooper]

Originally posted by vintage1
but normally I get about as far as the bedroom before I can hear twitches....

Isn't marriage wonderful? My wife is the same...;)

I digress; I tried the supplied bobbin/Feather combo on an IFO, and it was pretty hopeless. This could have been due to the amount of carbonfibre in the IFO itself. I then tried removing all the carbonfibre from the IFO but the covering went all floppy.

Without the bobbin, the Feather was OK-ish. I still use it in a vintage model, but I make sure it's flown close.

tim

[BMatthews]

Originally posted by vintage1
....vituperative factions...

I think I'm supposed to be mad at that........ I think........

:D

I used the bobbin on my Feather and noticed it DID glitch a lot before I decided that the Pico stick was inherently no fun to fly anyway and I put a foot through it after pulling all the gear.

I'll be putting the same gear into an enlarged Earl Stahl Fairchild F24 rubber scale model and the wire will be proudly dangling out the back side.

I didn't think it was a good idea even when I did it. U2Steve just confirmed it.

[U2Steve]

V'1:
I still believe that if you want reliable range, you need to go to a dual-conversion-type receiver with a full-length (half-(quarter?)wavelength, I think) antenna. Anything else is a compromise of looks, weight, and range.

As far as range checks vs. actual range goes, I remember reading in a post here someplace the opinion that the range check was useless. No one flies with their plane on the ground, or their Transmitter antenna collapsed, so beyond verifying that it actually works and your batteries are good what DOES it tell you?

Somewhat more vituperative,
Steve

[All__talk]

Hi guys

Coiling an antenna is a valid way to shorten it, but like with everything, there is a cost. I have spent quite a bit of time discussing antenna theory and design with a friend at work who spent most of his carrier designing RF equipment for the Russian military, here’s what I’ve learned:

Coiling the antenna will, through inductance, change the impedance and if the impedance is not readjusted the range (gain) will decrease, this adjustment is typically made by changing the overall conductor length (there are formula available to determine the proper length). The coiled (helix) antenna will have the same general pattern as the straight (mono pole) antenna, but due to its geometry, both diameter and spacing (step), it may nullify some adjacent frequencies, so if the now coiled antenna is not retuned, your transmitting frequency could fall in to one of these zones and the antennas ability to receive it may be greatly reduced or even eliminated. The range of the properly tuned coiled antenna will be less purely due to physics, it now covers less space in the air than the straight wire did. The choice of bobbin material can be critical, some dielectric materials can absorb large amounts of the antennas energy and greatly reduce range, the best bobbin material is air, which presents some difficulties supporting the wire, other good choices of materials can be dependant on frequency. Ultimately it comes down to “acceptable” range.

A note on ground range checks, the ground interferes with the signal and the antenna effectiveness increases the further it is from the earth. So the idea is that if you can get a given distance with the plane on the ground and the TX antenna collapsed (worst case for both plane and TX antennas), then the in use range will be MUCH larger. Its really just a rough confirmation of proper system operation and tells you little about the “as used” range.

Just passing on information from someone who actually knows something. :p
Gary

P.S. sorry for the length (engineers can be VERY wordy)

[vintage1]

Originally posted by U2Steve
V'1:
I still believe that if you want reliable range, you need to go to a dual-conversion-type receiver with a full-length (half-(quarter?)wavelength, I think) antenna. Anything else is a compromise of looks, weight, and range.

As far as range checks vs. actual range goes, I remember reading in a post here someplace the opinion that the range check was useless. No one flies with their plane on the ground, or their Transmitter antenna collapsed, so bey.ond verifying that it actually works and your batteries are good what DOES it tell you?

Somewhat more vituperative,
Steve

Oh, that is not correct. I have reliable range on 'normal' PPM stuff as far as I dare fly - about 500m. The only glitches I now see are the very occasional loss of signal when the old picojet wing with the antenna running down it is pointing right at me and I am pointing the tx right at it...then I hear the slightest hesitation in the motor note...maybe once per flight. I can live with that.

As for DC? No. I am not suffering the sorts of problems that DC would solve, so thats is a waste of money, and weight. DC isn't about more range per se, its about better tuning. and better rejection of other freqs.

As far as a full length aerial goes, I don't have room for that either.

On range checks, yes sure, 'in air' range is way bigger than on ground range.

If I can get 60-100m of reasonable range (the REX4 goes buzzy and twitchy at the limit) i'll fly - high and upwind! Old S/C habits die hard...should be about 300m in the air.

She is not a fast model, nor a big or colourful one. So there is no joy in squinting into the sun trying to work out which way up she is.