[hpsdr] New HPSDR card for VHF/UHF ?

[Phil Harman]

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 

 
  ----- Original Message ----- 
  From: ct1izu 
  To: hpsdr at openhpsdr.org 
  Sent: Monday, September 06, 2010 4:23 PM
  Subject: Re: [hpsdr] New HPSDR card for VHF/UHF ?


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  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 
  to a level 17 mixer on VHF/UHF ???

  My thoughts were a digital tx that doubled as a LO for a high level mixer as being a compromise solution.
  Shel CT1IZU


    ----- Original Message ----- 
    From: Maximo EA1DDO_HK1DX 
    To: hpsdr at openhpsdr.org 
    Sent: Monday, September 06, 2010 9:03 AM
    Subject: Re: [hpsdr] New HPSDR card for VHF/UHF ?


    ***** High Performance Software Defined Radio Discussion List *****




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    Hi,

    I am not sure if I understand you guys but what I think is a DDC in VHF/UHF.
    I am not talking about a HF SDR with analogic downconverters (as GNURadio).

    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.

    73, Maximo - EA1DDO






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