Jump to content
Lupy

best 2.4ghz xmitter antenna ?

Recommended Posts

I have a "500mw" 2.4ghz xmitter and reciever, here is the model:

http://www.felsweb.com/p3/500mw.htm

When I got it, several years ago, it had simple whip dipole antennas that measured .931" on the center element and .964" on the ground element. It had terrible range of only a couple hundred feet with lots of drop outs even much closer this caused me to abandon the project untill just recently.

I built the GP patch using one sided circuit board and since there was no connector, I mounted the reciever directly to the back of the antenna using a very tiny piece of coax, maybe .2" of shield, and a center long enough to reach the collector. It was a huge improvment, increasing the range to at least 250 yards with only a couple of dropouts in a 7min flight, I want to try farther, but need to change out the plane, which is curently a custom IFO. Since I am flying over water, the IFO is pretty risky. I have a Donald seaplane with a glass fuse and will probably mount the cammera in a waterproof box on the nose, and the xmitter inside, also water proofed. Changing the antenna around once it is installed will be difficult. so I would like to do it right the first time.

My questions: What is the best xmitter antenna, and should I worry about coax length for it aside from making it pretty short?

I run into ocasional notes about tuning the xmitter coax by trimming a length untill I get either max current, or min current depending on the antennna used. Is it dangerous to run the 500mw xmitter with just a lenght of coax, and no antenna? can it fry it?

Is the 4 legged ground plane antenna

( http://www.yb2normal.com/antenna3.html )

better than a simple dipole of the correct length?

I have also seen mention of a turnstile antenna, but the descriptions were a little unclear.

Thanks

Ken

Edited by Lupy

Share this post


Link to post
Share on other sites

With 500mW I think you should get 5 miles plus with just about any aerial !

Dont run the tx with no aerial, it will kill it before long.

Terry

Share this post


Link to post
Share on other sites

I do get the best results from the Yb2normal groundplane antenna (with the four stakes as ground) with my fels tx.......

Delcam

Share this post


Link to post
Share on other sites

Thanks for the advice, Delcam, what lenght of coax did you use for your tx? Any estimate of open air range you are getting?

Ken

Share this post


Link to post
Share on other sites

Hi All!

Just today I had to recognize again, that the small GP-Antenna (V3) from Yb2normal is really just the best and outperforms my cheap but professionally made 5dBi Omni.

But I still have some trouble with parts from the Model blocking the RF-path or tilting the plane that much that the GP points my way and RF is mostly in other direction...

I have 500mW Airwave/Felsweb TX, too. Any good Omni out there? I want tp place the Yb2- GP on the ground as "half-omni" together with a directional antenna, in a diversity-combi.

Greets,

Marcus

PS: I just ordered my kx141 with 90 and 64° FOV. Cant await its arrival... ;c) What is best FOV to fly FPV?

Share this post


Link to post
Share on other sites

depends on what you are doing, but I would think the 90 will give you a better view close to the ground, as you get higher, the 64 will give more detail as things will seem closer. It will also give a more square picture, with less fish eye than the 90deg. With 480 lines, you will need something better than a std camcorder viewfinder to really appreciate what's going on. I have a KT&C KPCHD230CWX, which is supost to be 520 lines, but is much heavier than the 141. It's easy to see the diferance from the 330line panasonic I was using when I download to the computer, but the viewfinder won't show much differance. I got a cy-visor, 1.4million pixles, so that should make the view much better.

As far as antennas, I have tried several others recently, and none seem to be as good as the 4 legged groundplane.

Ken

Share this post


Link to post
Share on other sites

I mostly use 70°. 90° is OK too, it's just a question of preference. I've never been able to tell which one was better. But I use the 70° as I prefer seeing more detail.

I've flown with a 116° a few times, now that's pretty weird!

Personally I don't really like the KX141. IMO the KX131 is far better. It has a very sharp image, excellent colours and contrast, reacts very fast to light condition changes and is very sensitive.

The KX141 has a pretty blurry image, the image is a bit too light and it needs relatively strong light to give good results.

Note that I say that in comparison to the KX131, which is the best I've used, it really has something "more" than the others. The KX141 will perform comparably to other CCDs.

I only recommend the KX141 if it's a weight issue.

Anyway I should try the KX141 with another optic. I wonder if that slight blur comes from the camera or the lens.

Share this post


Link to post
Share on other sites

Killrah and all,

yes, I can confirm the slightly blurry image of the kx141...

I got it basically because of the light-weight and high-resolution.

But somehow I do not want to believe that the 380 line kx131 shall be better than the 480 lines kx141!???

Any suggestions for a better lense for the kx141 to get a sharper image?

Greets,

Marcus

Share this post


Link to post
Share on other sites

This camera unfortunately doesn't use the standard board lens series like most of the others. I've never seen any that fits (apart form the other ones BW sells).

But I'm pretty sure the blur is due to the treatment done in the DSP. I'll try holding another lens in front of it and see if it changes something but i'm a bit doubtful...

Don't worry, I felt the same in the other way. I was used to the great KX131 and was sure the 141 would be better when it became available. I was deceived when I got it...

Share this post


Link to post
Share on other sites

Just before buying the KX 141 I send an e-mail to Kilrah asking him if this camera was good. I decided not to buy it evidently, Thanks.

It's amazing to see the best cam and the best headset on the market are still the equipment we buy 4-5 years ago.

When the lens mount is not the same, sometime I put a piece of thick paper around the lens and the lens stay firmly in place

Edited by Vrflyer

Share this post


Link to post
Share on other sites

Doesn't work here, it's not just untight but the KX141 lens has an inner thread...

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×