[hpsdr] Software Radio, Mixers and oscillators

[Phil Harman]

Hi Ulrich,

Please let me add my warm welcome to the group as well.  Your work has been an inspiration to me for many years. As I young ham I built the synthesised transceiver that you published in Ham Radio in the 70's. I used it as my main radio for many years and it was my pride an joy. 

The are a couple of areas where I would appreciate your comments.  Firstly is the local oscillator for  HF use. This is intended to divide down a GHz VCO. A discussion paper is at 

< http://www.hamsdr.com/dnld.aspx?id=356 >


One problem already pointed out is that we can't divide the 10MHz GPS locked reference within the LMX25** to give us an 800kHz reference. We could either use 400kHz steps and re do the math or double to 20MHz ( or phase lock a 20MHz VCXO to the 10MHz reference)  and stay with 800kHz steps.

The second is the design of the preamp for the high speed ADC front end. Here we are using an LT2208 135MSPS 16 bit A/D converter. My initial tests indicate a 100dB dynamic range with an overload point of 0dBm. Please see the discussion on the Wiki at 

< http://hpsdr.org/wiki/index.php?title=HpsdrWiki:Community_Portal >

under Mercury.

Your comments on the gain/attenuation prior to the ADC would be appreciated. 

73's Phil...VK6APH 




  ----- Original Message ----- 
  From: KA2WEU at aol.com 
  To: hpsdr at hpsdr.org 
  Sent: Saturday, July 08, 2006 10:25 PM
  Subject: [hpsdr] Software Radio, Mixers and oscillators


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




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  Hi guys

  let me know if I can help with mixers or oscillators 


  http://synergymwave.com/default.asp

  Ulrich L. Rohde, N1UL


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