The spectrum analyser is based on the W7ZOI design       PART 1       PART 2       SEE ALSO

I chose to design the analyser for 0 to 100 M Hz and settled on a 149.3 M Hz first IF.  This was because I already had a 160 M Hz Xtal oscillator and planned 10.7 M Hz (160 minus 149.3) second IF.
The VCO is a minicircuits POS300 and most of the other components were scavenged from the junk boxes., including a variety of double balanced mixers!
The POS 300 easily tunes from about 140 M Hz to over 300 M Hz with Plus 16V and minus 12 supplying the timebase.  
The first filter is critical and I found that a Toko 145 M Hz helical filter was quite selective enough and could be tuned to 150 M Hz.  However there were a few spurious responses and these were cleared by adding in series an old 144 transmitting bandpass filter which has very little loss but is too broad to be used on its own.  Its spurii must be different from the Toko filter as its addition cleared up all spurii.
The 10.7 filter is as in the articles and the narrow filter is a 25K FM Xtal filter, but as you will see in the pics below this is not ideal.
I used the modified Log amp using the ad603 and ad8307.  This chip is AMAZING!!  over 80db linear to log conversion and very linear on the output.
DISPLAY.
Only a scope with DC coupling and  xy input is needed. Low frequency response only
LAYOUT
Mindful of the need for screening I adopted a simple layout with all units in diecast boxes (mostly reused) and the many controls in the respective boxes fitted along the front of the analyser rather than design a custom front plate with leads to the controls.  This means that the only external interconnections are the power leads and the coaxial links.  The coax links were run through home made bulkhead type connectors to maintain integrity of the screening as suggested in the updates to the original articles. The faceplate was finished off with a half screen over the controls.  While not the most elegant solution this works well and looks reasonable..............