Sunday, November 22, 2009

HF3 grabber setup

This is what the present grabber setup looks like. The difficult thing is to adjust the BFO such that it is clear where it is. This receiver will not be modified, however, there is a second of this make on the way into my shack. One of the two will be modified, severely ;-)

The grabber is set to listen to QRSS signals on 3,599,900.0Hz. This may look odd, but, the HF3 is not aimed at radio amateurs, it is aimed at yachtsmen (like me). It particular to receiver TTY weather reports, weather charts via FAX, NAVTEX and occasionally some news on HF-BC using A3E. In marine station listings, the frequency for teletype stations given is the frequency between mark and space. To help the sailors, the processor of the radio sets the radio's PLL to the dial frequency for A3E and 2kHz below for J3E/USB. I have not checked J3E/LSB yet, since it is of no importance to me.
When using the HF3 as a grabber receiver, I thus set the dial to the actual frequency I want to listen on, knowing about the 2kHz difference.
To adjust the clarifier, use a time signal, or a known to be stable BC station, to adjust the carrier such that it precisely results in a 2kHz tone.
I tell spectrumlab the dial-frequency minus 2kHz as offset, in this example, it would be 3,597,000.0Hz.

The FRT-7700 makes a good general purpose tuner. It helps to improve all sorts of mis-matches.


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