Dear  RCindia Members,

I was doing some serious digging on this field for long range FPV in various other forums. was contemplating one option i.e. replace the stock antenna with a high gain antenna using a pig tail SMA connector.

Say if I replace the stock antenna with a omni directional 18dbi antenna using small pig tail photo graphs attached below.

One great advantage of using a SMA connector is that you can add a 2.4 ghz amplifier say 500 mw like the one in attached photograph in series before the high gain antenna.

I do not want to fry my Radio so thought I should seek advice of more experienced members in this field.

Would request more experienced members in this field or members who have come across this to pitch in and help.
 

This would require someone close to RF design issues to answer.

I have seen at least one case where a member of this forum used a high-gain D-Link WiFi antenna (some what like the one in the picture) on his spektrumized JR radio with good results.

The Omni directional 18dbi antenna has SMA connector which can been directly screwed on to the  SMA Pig tail. it has a foldable and rotatable base same like rubber ducky stock antenna. It is just four times longer than the stock antenna.

It is a 2.4Ghz antenna, Impedence is 50 ohms and max allowed RF wattage is 1 watts.

I was wondering what should be the impedance of Radio antenna? and what is the RF wattage of radio? is it 10mw or 100mw ?

has no one has even thought of doing this?

This topic is related... http://www.rcindia.org/radios-and-receivers/enhancing-range-of-radio-72-mhz/

Some serious hacks on this lines here

http://www.rcgroups.com/forums/showthread.php?t=833260

Found this relatively cheap ($60) 1Watt 2.4G Amplifier at DealXtreme

http://www.dealextreme.com/p/2-4ghz-1000mw-1w-wireless-ultra-range-extender-for-wifi-wlan-access-points-ap-and-routers-19616#open full view

It is meant to extend the Wifi router and directly take input from the feeder line which feeds the default Wifi antenna. since most of 2.4G RC TX have antenna with similar impedance to those of Wifi Router (evident from size/lading coil), there is high possibility that the integration would be smooth and you wont find issues like standing waves and antenna mis matching.

I think extending range with module would be better and you can get upto 25KM Range (LOS).
So, your 2.4GHz PCB would be of no require. But the receiver has to be matched. A few days before, I have seen this here. Just searching and add the reference link here.

Thanks

Quote from: ujjwaana on February 08, 2011, 05:09:13 PM
Found this relatively cheap ($60) 1Watt 2.4G Amplifier at DealXtreme

Thanks Ujjwana

This looks very promising and economical too as the 500mw amplifier posted as photo is available for Rs 5500/- in ebay.in

How is the feedback on buying from dealsextreame

Thanks @ Kalyan. But is it not desirable to leave the 2.4 Ghz Tx PCB in the radio and build on that so that when you are not flying Long range FPV, Just remove the addon Amp and antenna and replace with rubber ducky for regular flying.

Kalyan,
Though not much tested, the AMP method would be more straight forward, enjoying more power along with reliability of OEM encoding and Receivers. All you would need is the AMP and you can use all your receivers, like Sunderam sir says, you can switch between normal and high power mode at will.

Sumderam sir,
DealX is genuine shop but they have bad reputation for indefinite delays in shipping. Make sure you spend extra $2-$3 and add 'Tracking' option in the checkout page.

Do research more before buying it as I have myself not tried the Amplifier.

Thanks will do. I have seen a similar 1 watts amps being tried on rcgroups.

So definitely worth a try as I already have the pig tail and 18dbi omni directional rubber ducky. Only thing left was the amp.

Today received the 2.4 Ghz 1 watts amplifier from Rangevideo.com. It was for only $45 but with EMS of $25 for sure delivery along with many other products, proportionately it adds up $5-10 for shipping. At say $55 good buy. It came with the antenna, Pig tail SMA to Amp connecting cable.

http://www.rangevideo.com/index.php?main_page=product_info&products_id=245

Some Photographs of the Booster Amp which I have bought.

This Project of mine was extremely delayed basically due to two reasons.

Reason one I did not have the required UBEC for powering up the Booster RF 2.4 Ghz AMP from the transmitter Battery Pack. Second reason was that I was unable decide, as to which Radio I should pop open for this modification.

The 6EX with me was already modified for 900MHz Micro flying and had the 900 Mhz module inside. The question was between 7C and 10CHG. I was not able to get myself to risk attempting to modify the new 10CHG though that was what I wanted in the first place for future utility.

Decision was made easier for me by coincidence and bad luck, two weeks back when I dropped  the 10CHG, though from only 1 ft height only on the cemented hard floor. Bad luck for me it landed on the toggle switches on to one side and one of them, lever broke and other is bent and can break any time.  

Lucky for me I could find the Toggle Switch for me from ebay.com. Ordered two sets of all types in case of future breakages also . today the first set landed safe.

Since I have to open the 10CHG and do all the repair work now I think I will strap the Booster to the 10CHG itself.

Since this Booster amp requires a 5V 2 Amps Power supply, I have been able to obtain a 5V UBEC of Turnigy from HK. Which has also landed safe with other components. Now this project is good to go for me.

Quote from: sundaramvelar on July 13, 2011, 04:24:10 PM
I have been able to obtain a 5V UBEC of Turnigy from HK.

The Voltage specification on Rangevideo site says 6V.
Since you would be using the Tx Battery to power the AMP, I would recommend to use a Buck-Boost DC-DC converter. It has following advantages:

1. Lower noise than the BECs
2. Lower Heat
3. Lower energy waste(Due to (2))
4. Has a Pot with which you can more accurately set the O/P voltage.
http://cgi.ebay.com/DC-DC-Stepdown-Converter-Module-4-5-30V-OUT-1-25-26V-/280708249067?pt=LH_DefaultDomain_0&hash=item415b83f5eb

Thanks Ujjwanna,

I thought about that and wanted to buy it also later seeing that it was only for two amps long term rated output I dropped the idea.

Further this UBEC of turnigy is what is recommended by Range video for the booster Amp. Since it is housed in a metal enclosure and and has a heat sink it has low noise and has very low heat dissipation. This has further jumper to select between 5V/6V both 3 A output.

I even bought a Filtered Linear Power supply form Range video Which can be used for 5.8 Ghz Vedio Tx. But it is not supplying the recommended 3A Supply. So I am using it only for the 5.8Ghz Video Tx.

What is the range you are expecting?
According to me it may give upto 20 to 30 km LOS without glitch! if it is genuine
the one i am using wifi modem with 1 Watt ,manual says 60+miles i.e more than 100km but practically it is only 20 to 30 km LOS.

Quote from: sundaramvelar on July 13, 2011, 05:38:50 PM
Thanks Ujjwanna,

I thought about that and wanted to buy it also later seeing that it was only for two amps long term rated output I dropped the idea.

I even bought a Filtered Linear Power supply form Range video Which can be used for 5.8 Ghz Vedio Tx. But it is not supplying the recommended 3A Supply. So I am using it only for the 5.8Ghz Video Tx.

I have seen few 'Sealed' 5Amp DC-DC converters. Can send you the URL. Why did you need 5AMP on 5.8G Video Tx ? What is power of that ? should be max 600mA if you are using the immersion RC or the HK one. I am using a 3AMP Buck-Boost 'Up-Converter' and supply solid 12v to Video Tx using a 7.2V Lipo and everything remained cool!

Please give me URL of 5A DC DC converter if you have it.

I did not mentioned 5.8 Ghz Tx requires 5A supply!

The 5.8 Ghz tx  is of  range video only it is a metal box sealed COB. it is not consuming more than 500ma. The linear filtered power supply I am talking about is also only 700ma without heat sink. Only with heat sink it can supply more but even then it cannot cross 2A.

@praveen this is also 1watts wifi 2.4 Ghz Amp. Claimed to improve your range to 20 KM plus garunteed upto 10 KM with matching antenna. Better still with directional antenna.

There is a demonstration video in the range video where he takes the plane to 45 KM LOS on the same set up. Expends 12760 mah bty power. But he is not able reach back. Just 15 Kms short of home he crashes and plane recovered next day lipo fully wasted.

Quote from: sundaramvelar on July 13, 2011, 08:53:13 PM
Please give me URL of 5A DC DC converter if you have it.

You got it sir:

http://cgi.ebay.com/5A-LM2587-DC-DC-Converter-Boost-Power-Supply-Regulator-/220759523893?pt=LH_DefaultDomain_0&hash=item33664b0235

http://cgi.ebay.com/DC-DC-Converter-12V-24V-Step-Down-5V-5A-25W-/140571118755?pt=LH_DefaultDomain_0&hash=item20bab10ca3

http://cgi.ebay.com/KIM-055L-DC-DC-12V-Wide-I-P-9-35V-Step-Down-5V-5A-/260817459053?pt=LH_DefaultDomain_0&hash=item3cb9ee976d#ht_6551wt_1139

Thanks Ujjwaana,

@Praveen the Link for 45KM LOS demonstration FPV flight on the same setup is as below

How to find out whether the video tx is capable of giving the same or more range as of the radio. It really makes sense to have radio range less than video range so that rth kicks in. Is it only trial and error we could do to find out the actual range. There may be various factors affecting the range, but atleast I need the setup such that video tx exceeds the radio range.

Quote from: foamybuilder on July 14, 2011, 02:25:05 PM
It really makes sense to have radio range less than video range so that rth kicks in.

I dont think RTH has a dependency on the Video Tx Range to be less/more than the range of the Radio controller. The moment RSSI goes down, the RTH on the OSD/AP would kick in, whether there is a Video feed or naught.

what i meant was if you loose video link and you still have radio link to play with, how will you know the rth has kicked in. Most osds displays on the screen about the rth switch.
And in your previous post, rssi goes down means you have lost the radio link not the video link.