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[Towertalk] MFJ 890

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Subject: [Towertalk] MFJ 890
From: (Tom Rauch)
Date: Fri, 14 Jun 2002 21:59:04 -0400
> MFJ had one on display at Ham Com 2002 in Arlington TX last weekend. 
> They looked very interesting.  I had MFJ President, Martin F. Jue
> demonstrate it to me personally since I had bought a couple of clocks
> from his booth.  He explained that it sampled the various HF beacons
> around the world on a periodic basis, like every minute or two on
> several HF frequencies that started at 20 meters and went up to 10
> meters I believe.  The LEDs light up to indicate which beacon is being
> checked and you hear a short morse code identifier if that beacon is
> being received.

I'm afraid he might not have explained the operation clearly enough, 
or he doesn't really know how it works.

What actually happens is the MFJ-890 has a VLF receiver for WWV, and 
a microprocessor inside that is programmed to light an LED at the 
proper time for the NCDXF beacons to transmit.

When you select a band, the lights light in the order and location on 
a "map" when the beacons are scheduled to transmit. So every few 
minutes, you see the lights cycle through all the beacons. 

The MFJ-890 ***does NOT*** have an HF receiver inside, it is a 
microprocessor programmed to light the lights when a beacon 
transmits, and has a VLF receiver to synchronize on WWV. You can also 
synchronize the clock manually. (The unit I have here in Georgia 
locks on WWV even during daytime, but it may not work that well in 
poor locations. If it locks just once for a few minutes, it will 
remain accurate at least for the rest of the it should 
automatically set itself at almost any location in the USA.)   

To hear the beacons, your tune your normal HF receiver to the beacon 
frequency on the band you have selected. Then if you hear the beacon 
transmit when the 890 indicates it should be transmitting, you know 
the band is open.

73, Tom W8JI 

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