Re: [IRCA] [DXFlorida] Re: [NRC-AM] 1610 mystery station - Invitation to #mwdx

["Bob Foxworth" <rfoxwor1@xxxxxxxxxxxxxxx>]

Curt, the 1609 lower sideband, 1610 carrier and 1611 upper sideband
can appear to fade somewhat independently, just because of the
way the ionosphere can behave. I experienced this myself when listening
to 1610 with the DX390, in CW mode,  as I posted a couple of days ago.

Another manifestation of this is the "selective fading" sometimes
heard with AM detection when the carrier fades but the sidebands
do not, resulting in distortion that sounds like a single-sideband
signal.

A spectrum analyzer is the best reasonable tool to demonstrate this.

Curt wrote,

>There are a bunch of tones heard in AM mode, around what I think are
>three carriers, accounting for both modulated tones and heterodynes
>produced by the beating carriers. As I've mentioned, I get tones
>every 1 kHz from 1607-1613, in AM mode.


Possibly the modulator stage at the xmtr being overdriven by the
audio input, creating a spectrum of tones, which is being modulated
faithfully onto the RF carrier. That's a possibility, not an absolute
answer.


>I have also observed that the carriers vary in strength independently
>amongst themselves, which would tend to suggest separate signals, not
>a common one.


Not necessarily. See my remark at top.


>Last night there was one carrier at the times I checked and an
>impressed 1 kHz tone. Tonight it sure seems to me that there are
>three carriers, possibly with 1 kHz tones on some or all and the
>resulting hets as well. Also, I believe at some point last night
>there may have been three carriers -- reported by other -- but only
>for a short period, unlike tonight.

>Curt


- Bob        sent at 1052 est



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