AM Monitor Scopes for free (almost)



Tektronix 1710B looking at 651S-1 IF, with WWV signal.

For sixty years US television used the NTSC standard.  Now digital television has replaced almost all analog transmission.  An essential part of analog television transmission monitoring was a good waveform monitor (WFM).  They started out life as a two hundred pounder with 50 vacuum tubes, but later, some very nice WFMs were built which were small and lightweight.  An example would be the Tektronix 1710B.  These items are surplus at most video facilities.  I bought a unit in perfect condition for a whole Dollar at a university surplus store! 

WFMs are essentially a specialized oscilloscope; they have horizontal scan at 60 Hz and 15734 kHz.  The vertical response will be from a few Hz to around 4.5 MHz.  This means they will work on receiver IF's in the  450-500 kHz  range and also on 160 and 75 Meters.  The input sensitivity is around 1 Volt.  The photo shown above is an example of a Tek 1710B looking at the IF of a 651S-1, the signal is WWV (more ticks-more often).  The disruption in the picture is a scan rate issue between the camera and the WFM.

These things are gnarly to repair so I would find a working specimen and pay even $20 for a nice one. 

You will find AM especially a fun experience with an incoming envelope monitor.  A word of caution:  the R-388 / 51J3 (4) had a very poor IF output signature; it is crushed on one side (- going) due to the diode load of the detector.  So don't be too quick to be a modulation cop with your new instrumentation, but otherwise....  Have fun!



Other examples of small WFMs include the Leader and Hitachi units shown above.