[hpsdr] Proposal for a 'low-end' RX/TX board for HPSDR

[CT1IZU]

----- Original Message -----
From: "Lyle Johnson" <kk7p at wavecable.com>
To: "CT1IZU" <hands at iol.pt>
Cc: "Ray Anderson" <ray.anderson at xilinx.com>; <hpsdr at hpsdr.org>
Sent: Saturday, July 22, 2006 12:18 AM
Subject: Re: [hpsdr] Proposal for a 'low-end' RX/TX board for HPSDR


> What if we build the radio for only one band, or only two? The filters
> then require less space.


I wonder if we are looking at this from the wrong angle. If we configured
the board as 50R broad band in/out then are no longer limited to any given
use. A simple filter on vero in the coax lead gives you a Soft Rock, a loop
on the end on the coax a wide band sniffer right through to a 10 band
switched PA on a seperate board and enclosure.

In respect of my concerns about RFI into the mixers, a broad band board will
be much easier to properly screen. One of the DK6 guys does some nice
tinplate boxes beloved of the Microwave crowd. These boxes go as small as
37mm square and have top and bottom lids. Without the bottom on, a box could
be soldered onto the board around the mixer area and the bottom tack solder
on the other side. (Horst will know the manufacturer with the logo S)

If we put the LNA on the board with couple of gate switches we could use it
bi-laterial but under software control. This would allow us to drop it out
on rx on the lower bands but retain on TX.

Looking around at some my h/b transceivers here and then at the Atlas
backplane, a 10 band 10W board is a large lump to put on it even without
considering where the heatsink goes!

Shel CT1IZU



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