[R-390] Can you please help identify this?

[Bob Camp]

Hi

I used one of these for quite a while as a CW filter. They were a 
staple item on the surplus market for quite a few years.

Here's what it does:

1) Both setting: does no filtering at all.
2) Phone setting: notches out a narrow band at something like 1KHz.
3) Range setting: passes the 1 KHz tone through a fairly narrow band 
pass filter.

I'm not totally sure what the tone used was after all these years. It 
was a bit higher than the normal CW tone most hams use.

They were used in conjunction with aircraft navigation beacons. The 
beacons were AM modulated and generally operated below the AM broadcast 
band. They transmitted both CW and voice at the same time. Sitting 
there listening to the CW for hours just to keep up with the weather 
must have been a bit much.

An interesting variation on the system used two transmitters. They both 
sent CW at the same time. One transmitted only when the other one was 
off the air. One would send dots and the other one dashes. You could 
pick out the louder one by ear. Since the louder one was closer you 
could steer a line at an equal distance (range) from the two 
transmitters.


	Take Care!

		 Bob Camp
		KB8TQ





On Dec 18, 2004, at 4:03 PM, RLucch2098 at aol.com wrote:

> Hi All;
> I know this list in for R-390's but milcom List seems to be dead, maybe
> someone can tell me where to ask if no one here knows?
> Now, the unit:
> It would be nice to know its use & possible Part Number.
> I know the name marked is Beam-Finder.
> Seems to be an Audio filter & works nice.
> Any ideas?
> Pics:
> http://www.myradioroom.com/navybeam-finder1.jpg
> http://www.myradioroom.com/navybeam-finder3.jpg
> Tnx & 73..
> Rich WA2RQY
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