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!
Ted WA8ULG

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