[time-nuts] Acitve GPS antenna biasing
SAIDJACK at aol.com
SAIDJACK at aol.com
Fri Oct 9 03:32:59 UTC 2009
Hi Bruce,
these are very nice indeed.
I used these conical inductors in our 2004 FireFox broad-band synthesizer
prototype (working from DC to 1.64GHz), they are quite amazing.
But:
* you need a microscope and a VERY stable hand to solder them down, and
cut-off the unused wire. I damaged quite a few before I figured out how to
solder them. And once soldered, they need to be physically protected because
they are so extremely fragile
* if I remember correctly they won't sell to everyone due to military
applications (their main use)
* their current handling capacity is limited
* And they are very expensive.
I ended up designing the FireFox with a series connected bias-t using a
120nH inductor in series to a 150 Ohm power resistor in series to a 2.2uH/270
Ohm resistor combination.
That works very well up to over 1.6GHz, and costs pennies compared to $$.
bye,
Said
In a message dated 10/8/2009 19:33:06 Pacific Daylight Time,
bruce.griffiths at xtra.co.nz writes:
For broadband use a powdered iron filled conical choke such as:
http://www.piconics.com/BC/bc.pdf
May be more useful, provided it is oriented correctly with respect to
the microstrip transmission line.
Bruce
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