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

[Richard Knoppow]

     So what did they do in areas with  50Hz power, there were plenty of 
them in the U.S.
     There are detailed descriptions of the four course (sounds like a 
dinner special at the local chop house) radio ranges in several of the 
old engineering texts at www.tubebooks.org and elsewhere on the web.
     Not all range stations had voice communication, those that did had 
a separate transmitter and a center antenna for it.  The method of 
feeding the antenna array was interesting because it was arranged to 
move the overall orientation electrically and also to "squeeze" the 
beams to line them up with particular air routes. There were many 
problems with the range stations; planes could get on reciprocal 
bearings, the beams could be distorted by nearby large objects, and 
skywave transmission could be confusing and unreliable.  Most stations 
eventually had a VHF marker in the center pointing straight up to 
indicate when an aircraft was just over the station.  The range pattern 
was null straight up, called the Zone of Silence.
     A lot of the transmitting equipment was made by Wilcox Electric, I 
don't know what happened to them.

On 4/26/2016 10:06 AM, Michael Bittner wrote:
> 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
> --
>
>     ----- Original Message -----
>     *From:* DSP3 <mailto:jeepp at comcast.net>
>     *To:* arc5 at mailman.qth.net <mailto: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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-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL

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