Re BIAS TEE for powering antenna....

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Re BIAS TEE for powering antenna....

Postby USAFE501 » Wed Jan 01, 2020 9:57 pm

Happy New Year everyone,
Quick question if that's ok...

...getting started in hobby of monitoring Inmarsat transmissions and I have and sdr dongle with L band patch antenna.
The dongle has the capability of powering via software , the antenna however I also want to power the antenna NOT via the software.
I have seen bias tee available on ebay fairly cheap - the circuit board constructions are fine with two sma connectors and an input for power - Being rubbish at these things , what amount of power should be supplied to the circuit board ?
Descriptions say 50v max , but can I not just use a simple plug in the wall 12v adaptor (i have one with various voltages from 12v down to 0.5v)

Can anyone help please ?

Thanks in advance
K :smiles:
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Re: Re BIAS TEE for powering antenna....

Postby radiostationx » Wed Jan 01, 2020 10:26 pm

You can squirt power along a bit of coaxial from something like a labgear PSUFC (using the Amp output) and terminate this at the bias tee + -, nice unit, 12vdc @ 300ma..I use one for adsb, or you could use 1x or 2x 9volt smoke alarm batteries for 9v/18v but you would have to install the bias tee, battery/batteries and a little toggle or slide switch inside a box or something and turn off when not in use.
I take it you want to use a nooelec amp with the patch antenna from sdr kits which already has an amp built in ?
Sometimes people struggle with software for bias tee activation and drivers.
By far the most reliable dongle for this is the noolec smartee one with built in bias tee, you wont need the separate bias tee , it sends 5v down to the patch with no worries

https://www.amazon.co.uk/NooElec-NESDR-SMArTee-Integrated-R820T2-Based/dp/B079C3FHPG/ref=sr_1_2?


The patch will work much better if it is rotated 90 degrees for LHCP and even better if you use it facing an old sky mini dish . The donor dish you will find at a local dump or skip or volunteer to remove an unused one.
To do that some mods/fabbing will be needed to make a metal base on a small piece of ( around 32/35mm diameter ) pipe to fit the sky lnb arm or be creative and experiment with a bent coat hanger and a tin can and a cable tie !

Image

note the patch is rotated for LHCP

Image
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Re: Re BIAS TEE for powering antenna....

Postby USAFE501 » Thu Jan 02, 2020 1:08 am

Radiostationx,
Thanks for reply and photos, fantastic. :thumbup:
So I have the L band patch antenna and rtl sdr v3 dongle that via software, activates the bias tee powers the antenna.
If I use the noolec dongle as my sdr instead, as you suggest , I understand this dongle powers bias tee automatically WITHOUT software ?
So my next question is what sdr software do I use with the noolec ? my rtl v3 dongle currently uses SDR Uno and also sometimes sdr#

So sorry if my questions are really basic and you're probably thinking " What a numpty !!!!"......apologies for that :embarrased: :embarrased: :embarrased:

Thanks again for reply,
K :smiles:
USAFE501
 
Posts: 134
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Re: Re BIAS TEE for powering antenna....

Postby radiostationx » Thu Jan 02, 2020 1:31 am

USAFE501 wrote:Radiostationx,

So sorry if my questions are really basic and you're probably thinking " What a numpty !!!!"......apologies for that :embarrased: :embarrased: :embarrased:
K :smiles:




Not at all, You could spend many hours faffing with no results..been there,done that...so I will try to save you the pain.
You will defo need as much help as poss from as many users as poss for starting this branch of radio...we are all in learning mode with Jaero.


I have been there with V3 dongle led me a merry old dance with Jaero working sometimes and sometimes not, BE WARNED your software bias tee tick box could be lying to you or just when you think the 5 volts are on, they dissappear at random !, Such is RTLSDR V3 "witchcraft" the dongle is great for HF but not very good for this im afraid with bias tee volts essential.

TIP: to activate the bias tee sometimes needs a physical change on the PCB by soldering up 2 pads for early V3s to work see here

http://www.merseyradar.co.uk/airband-radio/two-dongles-compared/


I have loads of dongles,perhaps 15-20 or so in my little collection been buying them since about 2011 when the fc4000 tuner was the only one Ari at Cosycave in Gurnsey had, before the Rafael Micro r820t family came out.


The one I pointed out ( nooelec smartee) will give you no issues, it just works, better switching and no messing.

In terms of sdr radio Jaero set up isnt that easy at all for a beginner.

Before pi4 came out, Making Jaero work on a octo core android TV box with a dongle and armbian software was extremely difficult indeed, a solid 5 spanner job in the haynes manual of radio twiddling but nice challenge. :0)


sdr# seems more popular for Jaero as you can do more things with the output you are looking for but I very much like the scanning feature in SDRuno which is brill for civ/mil airband.
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