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New CHEAP LNA

Posted: Fri Aug 08, 2014 5:27 pm
by jonfear
All

Same as me, I guess every one wants a cheap 1090MHz amplifier. I have just found this on Cosycave and thought I would share it. I will be buying one to trial.

https://www.cosycave.co.uk/product.php?id_product=316

Best wishes

Jon

Re: New CHEAP LNA

Posted: Sat Aug 09, 2014 7:32 pm
by T-EGJA1
Interesting ... I look forward to your evaluation :)

Re: New CHEAP LNA

Posted: Thu Aug 14, 2014 7:46 am
by jonfear
Just got the LNA, this is my initial thoughts.

Using an internal GSM magmount antenna, R820T dongle from Cosycave and RTL1090 Beta 3.

Without LNA, about 50-80/messages per second, with LNA >180/second.

I will need to try it in a more controlled environment but it does look very good.

HTH

Jon

Re: New CHEAP LNA

Posted: Thu Aug 14, 2014 8:17 am
by manaesh
Thanks Jon

I am soon to be moving location, and will be looking to finally mount my CoLo outside, so am thinking of the best way to go about doing it.

How do you overcome the loss on the antenna cable to the antenna (i imagine it will be around 8 - 10m)? Will this preamp be any use at the dongle end - or will i need an amp sitting up at the antenna?

Cheers!

Mike

Re: New CHEAP LNA

Posted: Thu Aug 14, 2014 10:07 am
by jonfear
Hi Mike

If it only 8 -10m then the losses will be small. This LNA would certainly overcome any losses incurred. The LNA plugs into a USB port so it can be local to the machine.

HTH

Jon

Re: New CHEAP LNA

Posted: Sun Aug 17, 2014 11:33 am
by jonfear
OK, I have now had some time to play with the LNA here at home.

I have used a mag-mount GSM antenna similar to that used at work.

The LNA certainly has lots of gain, rather too much in fact. I have had to wind the gain on my RTL dongle back to approximately 40dB otherwise the front end overloads, even with an out of band antenna.

With the gain set at 40dB, It seems to be picking up aircraft much quicker than without. Due to the location of the antenna, I would say I am not seeing much greater range.

When I get my new antenna's from Nic Storey, I will set them up side by side and then feed two dongles so that I can compare the outputs and range. Should be interesting as the Antenna has 9dB already.

I would suggest to Cosycave that the connectors are better positioned in future builds. With the standard SMA to MCX lead from Cosycave, it is stretched and certainly under stress. If the connectors could be reversed, it would be better. If the connectors we put on the end of the PCB (opposite end to the USB connector, even better. Remember that most USB socket banks have little space between them!

So my gut feeling? For the money, well worth getting one to play with. It may be the answer to many systems which have poor performance. Remember however you do need a spare USB socket. I doubt that most Raspberry Pi's with a 1A power supply will be able to cope. I will try it out later with my new RPi B+ with the 2A power supply. I have a co-linear just waiting to be played with!

Hope this helps...

Jon

Re: New CHEAP LNA

Posted: Wed Aug 20, 2014 7:49 am
by milairuk
I've found these work well but you do have to feed power up the coax and make sure your antenna doesn't have a termination resistor on it if it's a colinear design.
http://www.ebay.co.uk/itm/330355208708? ... 1423.l2649
They provide adequate gain if run off the 5v USB line as well.

Because the power goes up the coax, they can be mounted at the antenna, which will give the best results.

John

Re: New CHEAP LNA

Posted: Wed Aug 20, 2014 8:53 am
by jonfear
John

Snap! I use one of those built into a diecast box, PSU connection, F Type chassis the works!

See my post about design in the thread: http://forum.virtualradarserver.co.uk/v ... ?f=9&t=425

Jon

Re: New CHEAP LNA

Posted: Wed Aug 20, 2014 1:35 pm
by milairuk
jonfear wrote:John

Snap! I use one of those built into a diecast box, PSU connection, F Type chassis the works!

See my post about design in the thread: http://forum.virtualradarserver.co.uk/v ... ?f=9&t=425

Jon
Great minds etc ... I'm using an 8 element homemade colinear mounted approx 10m AGL, so haven't really bothered to use this after I first purchased it. Also have 12 element home made one on my shed for experimental purposes !

Also played around with a MiniCircuits CBP-1090C filter I managed to get as a sample, but it didn't seem to make any difference apart from acting as a useful DC block to the DC coming out of the amplifier (always terminate my colinears with 75R !)

Have you looked at the nifty antenna from Adam http://ads-b-antenna.blogspot.co.uk/
This does need a preamp to get best results, I've mounted mine in a CCTV plastic dome, but haven't had time to get it put into use yet.

John

Re: New CHEAP LNA

Posted: Wed Aug 20, 2014 1:54 pm
by jonfear
Hi John

Just awaiting delivery of some antennas from China via Nic Storey. Hopefully be here for the weekend. From early results, it appears to be outperforming some of the best antennas on the market.

I am not sure that Nic will run a second batch order, perhaps someone else can take that on.

When I have my results I will publish them here. I do have some early screen shots from Nic if anyone is interested.

That will be the limit on my mode-s purchasing for now. I cannot justify a Beast or Cape or for that matter an SBS-3! Dongles are the future!

Jon