[ARC5] What is a "radio range filter"?

[Michael Bittner]

While we are on the subject of range/beam filters, I am still looking for a schematic diagram and/or wiring diagram for my F-90/AIC range/beam filter.  

Scott W7SVJ confirmed that its input and output impedances are 150 Ohms, and Mike Hanz provided information on its use in the Intercommunication Set AN/AIC-8.  However, its correct hookup and internal circuitry remain an enigma.

BTW, 1020 Hz is the 17th harmonic of 60 Hz.  Back in the day, the power line was used as a readily available frequency standard.

Mike, W6MAB
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  ----- Original Message ----- 
  From: DSP3 
  To: arc5 at mailman.qth.net 
  Sent: Tuesday, April 26, 2016 8:20 AM
  Subject: Re: [ARC5] What is a "radio range filter"?


  Brian has is pretty much correct.  The "range filter" was designed to pass 1020 Hz audio through the phone audio system of certain aircraft receivers when tuned to a "range station".  1020Hz became the de facto standard for Morse audio identifiers  of NDBs, VORs, Marker Beacon, etc. as well as the keyed tones for the now defunct Adcock system (the true range stations). Both the AAF and the Navy had their versions of the filter, some controlled at the filter, and some remotely switched in and out.  The FL-8 is one of the more prolific models.  Most current audio panels and Nav or NavCom sets will have a 1020 Hz filter circuit for the Marker Beacon channel and to selectively filter the identification audio from the other VOR/ILS modulations present.

  Jeep - K3HVG



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