<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META http-equiv=Content-Type content="text/html; charset=iso-8859-1">
<META content="MSHTML 6.00.2900.6003" name=GENERATOR>
<STYLE></STYLE>
</HEAD>
<BODY class=hmmessage bgColor=#ffffff>
<DIV><FONT face=Arial>Sam G4DDK's SUFFOLK is typical of a good
2mtr transverter and a front end that will handle a contest.</FONT></DIV>
<DIV><FONT face=Arial> It has typically a 2dB noise figure and an input IP3
of 0dBm. I would expect with a Merc 2nd IF, SYSTEM IP3 would be better
than -3dBm</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>Shel CT1IZU</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<BLOCKQUOTE
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=phil@pharman.org href="mailto:phil@pharman.org">Phil Harman</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=ct1izu@sapo.pt
href="mailto:ct1izu@sapo.pt">ct1izu</A> ; <A title=hpsdr@openhpsdr.org
href="mailto:hpsdr@openhpsdr.org">hpsdr@openhpsdr.org</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Monday, September 06, 2010 11:31
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [hpsdr] New HPSDR card for
VHF/UHF ?</DIV>
<DIV><BR></DIV>***** High Performance Software Defined Radio Discussion List
*****<BR><BR>
<P>
<HR>
<P></P>
<META content="MSHTML 8.00.6001.18939" name=GENERATOR>
<DIV><FONT face=Arial>Ok - lets do a few back of the envelope sums to see it
this will work or not.</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>If we assume that the ADC will have a noise figure
of 30dB at the frequency we wish to receive then we will need approximately
40dB of gain before it. This will ensure that the receiver noise figure
is dominated by that of the VHF/UHF front-end.</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>So with 40dB of gain the ADC will overload at +15dBm -40
= -25dBm.</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>Is a VHF/UHF receiver with an overload at this level
usable in Europe?</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>Alternatively, one of our members has built a
very high performance 2m transverter using the 122.88MHz clock
from Mercury as the drive to a high level mixer and then tuning
from 144-122.88 to 148-122.88MHz on Mercury.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial>73's Phil...VK6APH
<BR></FONT></DIV></BLOCKQUOTE></BODY></HTML>