Re: [FUNcube] Bias Tee
- View SourceHola Jose Maria!Thanks for all the good news. The bias tee feature then facilitates further howbrewing and tinkering. I will tinker, a lot!73,Franco iz2oosDa: jose maria trueba <josemariatrueba@...>
Inviato: Mercoledì 2 Novembre 2011 0:08
Oggetto: Re: [FUNcube] Bias TeeHi,
Filters located near FCD have to be prepared to pass RF to filter and DC to preamp at antenna feed point. Two choque and 3 capacitors make the job in my case (don't ask me the values, since I used what I had without much care).
No damage if grounded.
There's a resistor inside FCD that absorbs energy if output is to gnd.
5VDC are coming out FCD. Current can be as high as 100mA dropping to 4VDC, which is OK for MMICs. Your 39dBM IP3 preamp would be happy.
The TV pream probably accepts 24VDC+, so has to be modified to pass 5V bypassing regulator inside.
I think I had all your answers. Hope it helped.
Here I have some question about it:
1) I have helical filters as preselectors that are DC grounded. So, in the case I erroneously check the Bias Tee would I make any damage to the Funcube?
2) Which voltage is coming from the Bias Tee? How much current may be drawn? I have one "AM1" by "Watkins and Johnson" that has 14db gain from 60 to 3000Mhz and 39dbm OIP3 working up to 5.5V and 80mA and I wonder if I can use the Bias Tee to power it directly trough the coax.
3) I have one amplified TV internal aerial that is meant to be powered through coax. Would it be a so bad idea to power it by the bias tee of the Funcube?
73 and thanks,