> From: K9AY <k9ay@k9ay.com>
> Subject: Birdies
> To: "Mike Waters W0BTU" <mrscience65704@yahoo.com>
> Date: Monday, February 22, 2010, 11:45 AM
> Mike,
>
> The birdies are just part of the 160M landscape -- the fact
> that you hear them clearly is a credit to your receiving
> capabilities.
>
> Like you, I am not very close to an AM BC station (15
> miles), but there are quite loud birdies on 1820 and 1830,
> and smaller ones elsewhere. Most of that RF is coming from
> the Chicago area, where there are several 50 kW stations
> within a few miles of one another. Not hard to imagine a
> watt or two of intermod coming out of that mess!
>
> 73, Gary
> K9AY
Thank you, Gary.
At the prompting of Robin, WB6TZA, I did do some further quick checks about 3
PM, which showed me that a preamp here causes the birdies to appear during the
day. (I think it's the back-to-back protection diodes on the preamp's input,
but I'm not sure yet.)
No birdies during the day unless I switch in that preamp. Then, in the AM mode,
I can hear the audio from two stations.
But now, at 7 PM (still on the Beverages) I'm getting them without using a
preamp; even on a high-dynamic range receiver with input attenuation.
Robin kind of lit a fire under me to investigate the birdies further, and I'm
glad he did. More tests to follow. Maybe I'll find something else wrong here.
:-)
73 Mike
_______________________________________________
UR RST IS ... ... ..9 QSB QSB - hw? BK
|