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<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>
<DIV> </DIV>
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<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: black"><B>From:</B>
<A title=ct1izu@sapo.pt href="mailto:ct1izu@sapo.pt">ct1izu</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <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 4:23
PM</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
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<DIV><FONT face=Arial>I fully understand the objective but question if there
are any A to D converters that will allow a high performance front
end with equal performance </FONT></DIV>
<DIV><FONT face=Arial>to a level 17 mixer on VHF/UHF ???</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>My thoughts were a digital tx that doubled as a LO for a
high level mixer as being a compromise solution.</FONT></DIV>
<DIV><FONT face=Arial>Shel CT1IZU</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial></FONT> </DIV>
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<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: black"><B>From:</B>
<A title=ea1ddo@hotmail.com href="mailto:ea1ddo@hotmail.com">Maximo
EA1DDO_HK1DX</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <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 9:03
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>
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Hi,<BR><BR>I am not sure if I understand you guys but what I think is a DDC
in VHF/UHF.<BR>I am not talking about a HF SDR with analogic downconverters
(as GNURadio).<BR><BR>Now some hams are using HF SDR with analogic
downconverters, for example 144/28. What I said is to go VHF directly with
DDC, NO analogic downconverter used.<BR><BR>73, Maximo - EA1DDO<BR></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial></FONT> </DIV></BLOCKQUOTE>
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