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Old Mar 15, 2010, 05:54 PM
Martin - AKA mr.sneezy
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Adelaide, Australia
Joined May 2004
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Quote:
Originally Posted by Chase Wu View Post
Hi, BrumBob,
It's ok to put an extension coax and connector between the antenna and the mounting point, provided that the coax and connectors are made for MICROWAVE applications.
The connector is called SMA, and the coax impedance is 50 Ohm.
pls Enjoy it.
Hi Chase and Brumbob.
Question - Is the connector on the FrSky V8 TX module actually an SMA or an RP-SMA ?
(RP-SMA would have a pin in the center of it, not the socket. I don't own the V8 kit so I don't know)

If it's lucky enough to have the RP-SMA then you could fit a replacement antenna for the Spektrum modules to it Bob. Cheap and would look good too.
http://www.readyheli.com/SPM6810_Spe..._p/spm6810.htm

Martin
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Last edited by PLMS; Mar 15, 2010 at 06:01 PM.
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Old Mar 15, 2010, 07:07 PM
Extreme CNC Alloy EDF
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Australia
Joined Mar 2006
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Its SMA which is the annoying part, I have already asked them to supply an aerial the same as the HITEC one but to suit their modules.

John couldnt understand what I was on about but that photo is one I hadnt stumbled across, it shows exactly whats needed!

Chase can you please offer the above hitec style aerial as an option so us importers can have them available for the customer?

And to question the aerial design:
Wouldnt the fitting to the Tx be best to be the split pin shaft design which pushes into the FM aerial hole rather than sitting over the top? then you are guaranteed to fit most Tx's right?
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Old Mar 15, 2010, 08:13 PM
Martin - AKA mr.sneezy
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Adelaide, Australia
Joined May 2004
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Quote:
Originally Posted by Extreme_RC View Post
Its SMA which is the annoying part, I have already asked them to supply an aerial the same as the HITEC one but to suit their modules.

John couldnt understand what I was on about but that photo is one I hadnt stumbled across, it shows exactly whats needed!

Chase can you please offer the above hitec style aerial as an option so us importers can have them available for the customer?

And to question the aerial design:
Wouldnt the fitting to the Tx be best to be the split pin shaft design which pushes into the FM aerial hole rather than sitting over the top? then you are guaranteed to fit most Tx's right?
Thanks for confirming it's SMA (EDIT: later post says it's actually RP-SMA). OK, then theres plan B. It's a little more messy but I'd have no hesitations to do it.
http://www.readyheli.com/EFLB1058_Tr...p/eflh1058.htm
This option involves removing the original SMA socket from the TX module completely and plugging this other replacement antenna in instead.
The FrSky board should have an U.FL socket on it same as used by nearly all RC 2.4Ghz systems.
Martin
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Last edited by PLMS; Mar 17, 2010 at 09:16 PM.
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Old Mar 16, 2010, 04:00 AM
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Joined Jul 2009
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Quote:
Originally Posted by RENATOA View Post
Hi,Renatoa
thanks for your weblike
but i check it,there is no TX right?
Does there rf and rx compatible Chinese other brand radio?
thanks
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Old Mar 16, 2010, 05:25 AM
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Birmingham, UK
Joined Apr 2007
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Isn't the Spektrum aerial a lot shorter, ie different gain?
I thought the FrSky was RP-SMA - must look again when I get home. I've got an RP-SMA right angle adapter, I haven't yet tried a range check using it, but it did screw on ok.

And yes, it does use a ufl socket on the rf board. If you don't intend swapping modules, it would be possible to connect a ufl-SMA extension passing into the transmitter case to an aerial mount point in the case top, reducing the amount of coax flapping around at the rear.
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Old Mar 16, 2010, 05:39 AM
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Romania, Dolj, Craiova
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Quote:
Originally Posted by happy mind View Post
Hi,Renatoa
thanks for your weblike
but i check it,there is no TX right?
Does there rf and rx compatible Chinese other brand radio?
thanks
No Tx, right, but I am sure Mr. Chase has an ace hidden for the future

The modules and receivers are not compatible with other brand, afaik. Actually, in 2.4Ghz there is no such thing as compatibility, as in FM.
Everyone has his own proprietary encoding.
The only compatibility is at the Tx cases and pinout, to match Futaba/Hitec/Jr radios.
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Old Mar 16, 2010, 05:42 AM
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Romania, Dolj, Craiova
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Quote:
Originally Posted by PLMS View Post
Thanks for confirming it's SMA. OK, then theres plan B. It's a little more messy but I'd have no hesitations to do it.
...
This option involves removing the original SMA socket from the TX module completely and plugging this other replacement antenna in instead.
The FrSky board should have an U.FL socket on it same as used by nearly all RC 2.4Ghz systems.
Martin
Actualy it does have an U.FL socket, I seen in your pictures the other thread, where is an uncased Tx module board.
Beware that U.FL plugs are not designed with a long life in mind, they support at most 5-10 disconnect-connect operations !
I would go for the same approach, replacing antenna at the board level, without no other intermediate SMA plug, which steal at least 0.5dB of signal.
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Old Mar 16, 2010, 05:50 AM
Dan Thompson (MP8K developer)
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USA, KY, Paris
Joined Dec 2002
329 Posts
Quote:
Originally Posted by BrumBob View Post
Isn't the Spektrum aerial a lot shorter, ie different gain?
If you disect any of the 2.4 GHz antennas, I think you will find a coaxial antenna hidden in the last 50 mm of the antenna case. The other length of the plastic has nothing to do with the antenna except make it appear longer.

Where the manufacturers get their gain numbers is beyond me. Antenna comparisons used to be made against a dipole antenna which was the standard to which the compare was made. A coaxial antenna is essentially the same as a dipole. 2 db gain as compared to what? Marketing??????
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Old Mar 16, 2010, 05:55 AM
Dan Thompson (MP8K developer)
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USA, KY, Paris
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All of the antennas in the picture performed identically on a range test. Look at the difference in the physical construction.
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Old Mar 16, 2010, 07:33 PM
Martin - AKA mr.sneezy
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Adelaide, Australia
Joined May 2004
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Quote:
Originally Posted by Iflyj3 View Post
If you disect any of the 2.4 GHz antennas, I think you will find a coaxial antenna hidden in the last 50 mm of the antenna case. The other length of the plastic has nothing to do with the antenna except make it appear longer.

Where the manufacturers get their gain numbers is beyond me. Antenna comparisons used to be made against a dipole antenna which was the standard to which the compare was made. A coaxial antenna is essentially the same as a dipole. 2 db gain as compared to what? Marketing??????
May as well go off topic for a bit as not much new FrSky stuff is happening right now...

Yes good info about the gains and the lengths above.
Physical length is as said above, irrelevant (as long as it's not being shrouded by the TX's metal handle).

More gain is a problem, if you don't understand the way they work.
Unlike many things where 'more' = 'better', RF antenna gain comes at a price, that being the radiating pattern. Low gain dipole antennas (like these) are fairly unidirectional in the way they emmit the signal, and that's good for RC aircraft where the model may be at various heights and angles from the TX. High gain antennas (stacked dipoles or similar) radiate unevenly so the signal is stronger in the horizontal plane (gain) and consequently has less signal in the vertical, that's not so good for model aircraft as the signal drops off a lot if the model flies over the tip of the antenna when the antenna is upright.

My own choice is to fly with the lowest gain types, typically the 2dBi standard types. I avoid the 'high gain' types for RC, but they are great for my WiFi Router :-)

Actually I have another idea about the way we should be using our 2.4Ghz antennas if anyone still interested in more OT chat ?
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Old Mar 17, 2010, 04:31 AM
Speed is Good!
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Chippenham, Wilts
Joined Oct 2005
571 Posts
I think I'll wait for a Futaba module that fits like the JR module. I'm not happy about the aerial position. I'm in no hurry as I mainly fly gliders. Its really for the occasional electric park fly models
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Old Mar 17, 2010, 02:17 PM
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Eden Prairie, MN
Joined May 2008
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It is a shame it doesn't have that hard-case, but for those with Hitec Tx's I can see the need for flexibility.
C
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Old Mar 17, 2010, 02:49 PM
Registered User
Birmingham, UK
Joined Apr 2007
511 Posts
Quote:
Originally Posted by PLMS View Post
Hi Chase and Brumbob.
Question - Is the connector on the FrSky V8 TX module actually an SMA or an RP-SMA ?
(RP-SMA would have a pin in the center of it, not the socket. I don't own the V8 kit so I don't know)

If it's lucky enough to have the RP-SMA then you could fit a replacement antenna for the Spektrum modules to it Bob. Cheap and would look good too.
http://www.readyheli.com/SPM6810_Spe..._p/spm6810.htm

Martin
I've sat quiet and bided my time, but now I'm at home with the transmitter module in front of me, I'll confirm it is definitely RP-SMA, not SMA. The socket (externally threaded bit the aerial screws on to) on the module has a pin, and the RP-SMA right angle adapter is definitely the right polarity fitting for it.

Someone on the UK forums reckons that a dedicated Futaba module (styled like the JR) will be available in May. Any comment Chase? Is there any chance that module cases would be made available to upgrade old style units?
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Last edited by BrumBob; Mar 17, 2010 at 02:54 PM.
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Old Mar 17, 2010, 03:12 PM
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Romania, Dolj, Craiova
Joined Sep 2007
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Still not get what's wrong with this case and what is it missing to be Futaba enough ?
Has it the right pinout? Does it plug in any Futaba radio ?
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Old Mar 17, 2010, 03:30 PM
"The Judge"
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Sweden
Joined Feb 2006
5,817 Posts
Hello, i have recieved JR module FrSKy and 3 receivers 8 channel, system shows very good test data so far.

Can I ask the owner of FrsSky, for how long are you planning to make this stuff ? Because many companies produce one version then the next year, its a new version none compatible to the one you have got.. thats bad.

Are you planning to produce these system for a long time ?
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