Notes regarding the 1998 QST Spectrum Analyzer   
Updated on 22 Jan 2020,  Revised on 18 March 2021

I should have known.
  In early 2020 I was extracting old files from the w7zoi webpage in an effort to gain more room for new things.   The part of the web page relating to the 1998 QST paper that K7TAU and I coauthored (QST, August and September, 1998) had not seen much activity in two years, so I shaved it down.    But now, in late 2020 and early 2021, I'm seeing renewed interest in the spectrum analyzer project, including some folks who have actually built one.   (How gratifying!)  So, I'm pulling some of that old material back into this section.     Those building this spectrum analyzer, or a similar one should be sure to take a look at the refinements that we included in Chapter 7 of Experimental Methods in RF Design.

While this material relates specifically to the 1998 QST system, many of the items may have broader application.  

RCA Plugs and Sockets 
   This excellent piece from K7NHI is of general interest for those not wishing to specialize in SMA connectors.
VHF LC Bandpass Filters
     This module is an improvement over the one we used in the 1998 article.   There's more shielding, including a lot between filter resonators, but it's worth it.
A Simple VHF LC Bandpass.
     This circuit was one I built long ago, but the circuit may still be a useful element in an experimenter's bag of tricks.
Other variations for the VHF Bandpass LC Filter
      This note describes some experiments by VU2ESE and K3NHI.
VHF Crystal Oscillator Experiments
      Experiments led to a refinement for the 100 MHz and 110 MHz 5th overtone oscillator used in the spectrum analyzer. 
Early Spectrum Analyzer Updates and Mods
      This outlines some of the earliest activity, including hints about adopting other narrow filters.
Later SA Refinements
      The saga goes on.....
Spectrum Analyzer Operation with a Digital Storage Oscilloscope
       Triggering and similar details related to a DSO.   Bottom line:  It's the only way to go.
Tracking Generator Modifications and Recommendations
        Bob Kopski, K3NHI, and John Lawson, K5IRK, came up with a modification for the tracking generator going with the QST SA. Great work.