Feedback FM610 digital frequency meter
  
     
    
  This frequency counter by a manufacturer named
  “Feedback” doesn't really look like a very
  professional instrument.
  It comes in a cheap plastic case.
  But its
  Sperry Panaplex flat panel displays make it special.
  It doesn't work well yet, but it will.
    
   
  
  
  I had never heard of the “Feedback” brand
  until I saw this counter on the quarterly
  
NVHR
  swapmeet.
  It didn't look very special, but the size and colour of the
  display window made me curious.
  When I peeked through the front window
  with the light coming in at the right angle,
  I saw the shiny metal strips of a Panaplex display.
  The price was right, so I bought it.
  A manual didn't come with it though. And I will need it.
  
  This British made, Belgian used counter has three ranges:
  
  There are also buttons to select the trigger slope, set
  an input filter and set the input sensitivity and two
  controls to set the time between measurement cycles and the
  trigger level. A very basic counter.
  
  The display consists of two Sperry Panaplex displays
  and has a total of 6 digits.
  Panaplex displays are flat, 7-segment neon displays.
  I haven't yet opened the counter so I don't know what
  more technology is inside.
  
  When I switched it on, the display lit.
  The “GATE” light reacted to a signal I gave
  at the input.
  But the number on the display didn't have any bearing to
  the frequency of the signal.
  
  So I will have to find a manual or find out how it works myself.
  In the meanwhile, I'm happy to have this Panaplex counter.
  The numbers are wrong, but they are beautiful!