[AMRadio] 1500 KHz trap for NC-156

Larry Szendrei ne1s at neandertech.com
Mon Aug 11 13:54:07 EDT 2008

Hi Jim,

Apologies if my post was confusing.

Yes, I'm attempting to reject 1500 KHz, which is the IF frequency.

The receiver covers 0.3 - 1.2 MHz, and 1.7 - 17 MHz, skipping a band
approximately centered about the IF frequency. Therefore, the ideal (and
impossible) filter would be a brick wall stopband from 1.2 - 1.7 MHz, with
zero attenuation outside of that range.

I mentioned 80M only to comment that I noticed no attenuation that far
removed from the filter center frequency.

Yes, I wanted minimal attenuation at 160M as well. There were no signals
on that band when I was playing with this last night around 7PM local time
to use for reference, which is why I didn't quote attenuation for 160M.
However I was hearing plenty of static crashes on 160M with and without
the filter. I imagine the attenuation on 160M will be somewhat similar to
what I saw at 1.13 MHZ, roughly 12 dB - nothing to write home about, and
hardly optimized, but good enough considering the time and effort I care
to invest in this particular project.


----- Original Message -----
From: "Jim Tonne" <tonne at comcast.net>
Sent: Mon, August 11, 2008 13:33
Subject:Re: [AMRadio] 1500 KHz trap for NC-156


Let me jump in on that trap thing for just a

You are trying to reject what frequency / frequencies?

And you want to pass what frequency / frequencies?

Reading your last mail here leaves me confused as to
what you wanted to do.  I thought you wanted to
reject 1500 or so and still pass 160 meter band but
you just now mentioned 1100 and the 80 meter band.

- JimT

----- End of original message -----

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