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

Tue Apr 26 16:55:16 EDT 2016

OOPS!  Meant 50Hz, of course. 

Mac
On Apr 26, 2016, at 15:18, D C _Mac_ Macdonald <k2gkk at hotmail.com> wrote:

I never heard of any US area that used 60 Hz power but areas around Niagara Falls used 25 Hz as late as 1950s! 

Mac, K2GKK/5 in OKC, OK 

Sent from my iPhone

On Apr 26, 2016, at 13:30, Richard Knoppow <1oldlens1 at ix.netcom.com> wrote:

    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
> 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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-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL
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