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Does the suffix of a VNA ever change the freuqency range?

Question asked by drkirkby on Sep 21, 2012
Latest reply on Sep 22, 2012 by bhokkan
*Short question*
Does the suffix of a VNA, such as 8753A, 8753B, 8720A, 8720D ever effect the frequency range? Is it safe to assume that any VNA starting with the model 8720 covers 50 MHz to 20 GHz? I think this is true for the 8720, but does it apply to all VNAs that support the GPIB interface? 

*My reason for wanting this.* 

I'm trying to write a bit of code to control a couple of VNAs by GPIB. I'm mainly doing this for my 8720D and 8753A, but I thought I might as well make it as generic as possible, so it works with as many VNAs as possible. Then I can open-source it, so anyone can use it if they want. 

One thing I need to ensure is that any frequency I try to set is within the range of the instrument. So I check an identification string  and use that to decide 

   if( (strstr( identification_string ,"HEWLETT PACKARD,8720") != NULL ) && ((frequency < 50) || (frequency > 22000))) {
      fprintf(stderr,"The HP 8720 VNA works from 50 MHz to 22000 MHz\n");
      exit(1);
   }
   else if( (strstr( identification_string ,"HEWLETT PACKARD,8753") != NULL ) && ((frequency < 0.3) || (frequency > 3000))) {
     fprintf(stderr,"The HP 8753 works from 0.3 MHz to 3000 MHz\n");
     exit(1);
   }

I know some of the newer instruments like the FieldfFox have a frequency range set by an option. But I'm not too bothered about that, since it is not GPIB.  

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