[hpsdr] New HPSDR card for VHF/UHF ?

[ct1izu]

Sam G4DDK's SUFFOLK is typical of a good 2mtr transverter and a front end that will handle a contest.
 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

Shel CT1IZU



  ----- Original Message ----- 
  From: Phil Harman 
  To: ct1izu ; hpsdr at openhpsdr.org 
  Sent: Monday, September 06, 2010 11:31 AM
  Subject: Re: [hpsdr] New HPSDR card for VHF/UHF ?


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  Ok - lets do a few back of the envelope sums to see it this will work or not.

  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.

  So with 40dB of gain the ADC will overload at +15dBm -40 = -25dBm.

  Is a VHF/UHF receiver with an overload at this level usable in Europe?

  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.

  73's Phil...VK6APH 
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