[Lowfer] Loran Lines

Sun, 23 Nov 2003 06:43:57 -0500

John

I'll go with you on #1 through #3.

If the preamplifier or receiver were getting "crunched", 2nd and 3rd order
IMD products would not fall on the frequencies predicted by your loran chart
based on GRI.

A simple check for a "phantom" signal,  whether loran or otherwise, would be
to read the signal level of the suspect signal on Argo. Then,  insert a 10
dB attenuator between the antenna and the preamplifier and check to see that
Argo dropped by 10 dB (+ or - due to attenuator and Argo accuracy). If the
signal drops by 10 dB you can "safetly" assume it's real; if it drops at a
higher rate it is likely an IMD artifact - twice the drop for 2nd order, 3
times the drop for 3rd order and so on.

At my location, the RF-590 (with the normal amount of front end attenuation
and antennas tuned to 136 kHz) receiver sees a 100 kHz loran signal that is
100 uV using the 100' circumference shielded loop and 1 uV using the 14T 10'
octoloop. These signal levels shouldn't cause any receiver problems.

Jay

----- Original Message ----- 
From: "John Andrews" <[email protected]>
To: <[email protected]>
Sent: Saturday, November 22, 2003 2:56 PM
Subject: Re: [Lowfer] Loran Lines

> Mitch's post got me to thinking (ouch)...  I had assumed all along that
the
> Loran lines were a result of the transmitting process, and were simply
> signals that would be received along with everything else. Inability to
see
> them would be due to things like:
>
> 1. A receiving location that does not have strong Loran signals.
>
> 2. A deaf receiver/antenna system.
>
> 3. A directional receiving antenna.
>
> But perhaps some of the "damage" is done in the receiver or preamp when
> presented with a strong signal on 100 kHz. Has anyone tried either
bandpass
> filtering the 137 kHz area or notch filtering the 100 kHz region?
>
> John Andrews
>
>
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