Re: [Discuss-gnuradio] WBX needs external filter?

[Matt Ettus]

On 02/08/2010 09:31 AM, Kunal Rele wrote:
> Hi, I am using the new WBX board and wanted to know if it needs external
> filters for better reception.


The WBX has a wide-open front end, so strong signals can cause intermod. 
 It does have very good dynamic range, so that shouldn't be a problem 
except in the more extreme cases.

The small front end board (the grand-daughterboard or GDB for short) has 
a place to put a filter.  Mini-circuits has a whole family that fits 
that footprint.  Populated on the board as it ships is a 2.2 GHz LPF.

Also keep in mind that the transmitter will output harmonics, primarily 
the 3rd and 5th.  So if you're transmitting at about 750 MHz or lower, 
your third harmonic will also be transmitting.

The main purpose to having the GDB system is for people to be able to 
have different frontends for different purposes.  For example, you could 
make one with filters for all the mobile phone bands, or you could make 
one with filters for the amateur bands, or TV bands, etc.  You can also 
build in a higher power amplifier there if you like.  It should be 
simple to do that if you look at the schematics.

Matt