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Old Feb 11, 2007, 07:47 PM
GOK
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Need advice on a downlink system

I am looking into making a budget entry into FPV (first person video). and am looking through ebay for some cheap components.

I know a few people here use cheap off-ebay downlink setups on their AP ships.

Can anyone here comment on the usability of the below system as a basic downlink? I only want to be able to frame my stills and videos at this point so I am not really after a high quality system. A few things I am worried about with this setup though are the

-bulky cables and connectors, can these be replaced with smaller connectors?

-the tuning knob on the receiver. Do these manualy tuned receivers need constant attention to keep the reception good?

-and the need of a 9V battery. Can I use a 3s lipo for this?

Any feedback would be appreciated

http://cgi.ebay.com.au/2-4Ghz-200mw-...QQcmdZViewItem

Cheers,

GOK
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Old Feb 11, 2007, 07:53 PM
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I think most people will advise against the El-Cheepo cameras off of ebay. To give you an idea of what an El-Cheepo setup can do here's a few videos from a couple years ago when I went that route..

Around the court

Parking Lot

FPV Sailing

FPV Sailing part 2

The Sailboat and Car I was only able to get about 50 feet out before I'd get snow. Keep in mind that this is close to the ground transmission. To be more specific it was this setup I used back then..
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Old Feb 11, 2007, 07:57 PM
GOK
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Thanks for the advice,

They do look quite bad, but still seem usable for framing pictures.

mmhhh!?

Low range is an issue of course. This system on ebay says it has 1500m of range but i wonder if the claim can be trusted.

GOK
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Old Feb 11, 2007, 08:01 PM
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Quote:
Originally Posted by GOK
They do look quite bad, but still seem usable for framing pictures.
Hmm yeah using it for framing might not be so bad. In those cases you are flying 95% external and just using the video for a quick glance.

Quote:
Low range is an issue of course. This system on ebay says it has 1500m of range but i wonder if the claim can be trusted.
Keep in mind that WiFi boasts the same ranges outdoors. Depending on the environmental conditions your mileage may vary. Ask the seller if that is 200mw of output power, or 200mw of voltage draw. Some like to fool you by listing the power draw.
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Old Feb 11, 2007, 08:12 PM
GOK
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[/QUOTE]To be more specific it was this setup I used back then..[/QUOTE]

Hmm, I've seen that system as well, asked th eseller and he said that it had a 50-100m reception, and that the one I am currently looking at has much better range than that one.

I'll ask that 200mw issue.

Thanks,

GOK
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Old Feb 11, 2007, 08:58 PM
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I'm working on a project that hopefully will be funded. Against everyones advice I bought a cheapo system for $35 on E-bay. It was supposed to be 2.4 Ghz with a 100m range. To show the naysayers that this would actually work
It was a 1.2 Ghz system and had a 35 foot range (12m).. Pretty cool to put in your backyard but a true POS for anything else. To prove my concept I was zipping my Ez star at about 25 feet of altitude in a 15 mile an hour wind pretty hairball.. Ultimately they got the picture, but it was a weak display...

When I informed the seller that it was illegal for me to have a 1.2 Ghz system , he promptly offered to refund my cash.. We will see what happens.. Listen to the people here maybe a few have gotten decent systems on EBay but I for one won't be buying video equipment there

My 2cents...
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Old Feb 11, 2007, 09:04 PM
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Quote:
Originally Posted by monkeywrencher
Listen to the people here maybe a few have gotten decent systems on EBay but I for one won't be buying video equipment there
Yeah after looking at the pictures some more it looks like this TX is very close to the current setup everyone uses. That's why I wanted to be more specific on the setup I was using with those videos..

I tried Google'ing the model number of the unit, KL-2400, and didn't turn up very much. One hit was for a model forum over in France. The guy was asking how the wires are hooked up. Our current most of our setups are made in Taiwan where this one is from Japan. When you get the unit I'd love to see some video samples.
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Old Feb 11, 2007, 10:55 PM
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Gok, It's really hard to tell a good system on ebay, Most of the people here have at least one "it's so cheap, i've just got to try it" system around. I have a couple myself.

That being said, the xmitter does look like a resonable 200mw unit, and at least the reciever is missing the big silver tuning knob, which is a dead givaway of a really cheap set. It's a 9-12v xmitter, so you need 3 cells. It at least resembles the lawmate stuff, which is generally regarded as what to buy.

For that price, the camera has to be a cmos unit, which will not give you good results. At a minimum, be prepared to replace the camera with something for $70 USA or so, and be prepared to replace the rx antenna with a flat patch.

Even then, 1500M is streaching things for 200wm. I would expect 400m or so usable range under good conditions for 200mw with a 8db flat patch (YMMV)

It's about $55 Euros delivered, Which compares to about $114 + shipping for an equivelent power Xmitter and reciever from Future Hobbies. The difference is that the Future hobbies unit is a known element, from a known vender. You might get lucky, but there are a lot of threads over the years talking about too good to be true xmitters on ebay. Most turn out to be less than advertised.

Ken
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Old Feb 13, 2007, 02:28 AM
GOK
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Guys,

Thanks for all the advice. After hearing good stuff from a user of the same setup from the Australia forums, I decided to go ahead and buy the system. This person (cant remember the name now) (Rememberred it now. his nick was Pitts) said that he taped it to his kid's bike and followed him from his home on a laptop as far away as approx 1000meters without any breakups.

So I am guessing this would suit my purposes as a cheap entry into the 'downlik world'.

His only issue was with the CMOS camera that came with it. He said although it was usable, when he used his CCD camera with this setup connected to the TV he was getting briliant results.

I'll let you guys know how I go.

Thanks again,

GOK
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Old Feb 13, 2007, 02:30 AM
GOK
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Ohh,

Here are a few more questions. What exactly is a patch antena? what does it do and how does it do it? I am quite naive with electrics/electronics.

And would there be any suggestions as to how I can replace the bulky connecters with smaller ones?

Cheers,

GOK
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Old Feb 13, 2007, 10:52 AM
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Patch antenna is usually a square flat antenna that detects signals in a given direction.. You also have Omni's, and High Gain Directional.. Think of them this way. With light bulbs you have regular, flood, and spot lights. An Omni directional antenna is like a regular light bulb. It shines light all around the room. A patch antenna is more like a flood light. Instead of shining light all around the room, you're going to shine on one wall. Then a High Gain Directional antenna is like a spot light. Instead of filling the room, or shining on the whole wall... The light is focused on a picture on the wall.

When you look at most antenna specs it will list how the beam is focused.. For example..

Frequency 2400-2500 MHz
Horizontal Beam Width 75 degrees
Vertical Beam Width 65 degrees


And here is what it would look like...



Hope that helps out a bit!
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Old Feb 13, 2007, 02:20 PM
GOK
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Thanks for that great explenation.

GOK
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Old Mar 01, 2007, 04:09 AM
GOK
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My downlink system arrived today and with it some problems of course since it is off ebay

Actually, the system works perfectly fine when powered from the wall. However, when I use the 9V batteries with it I can't get anything I've even tried a 3s pack to see if 9V wasn't enough (on the wall adopter it reads 12V. But the 3s lipo didn't work either.

Can anyone guess why this would be?

On another note, When I connect the whole thing to the TV I can see the image perfectly, When I connect it to my MiniDV (which I want to use for recording) I get nothing

My hunch is that I am doing something silly because of my inexperience with these things.

Any comments would be appreciated.

Cheers,

GOK

Ohh, one more thing. When I power the TX off the wall it gets pretty hot. Is this common?
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