Hi Dennis.
I manage quite well with a simple two reasonator filter with tapped
capacitors for input and output impedance matching, response as follows,
centre 501.9,
3dB, 495.8 & 508.26, 6dB, 492.77 & 511.3, 24dB, 468.43 & 532.52,
30dB, 453.97 & 543.25.
73
Ken
M0KHW
----- Original Message -----
From: "Dennis" <[email protected]>
To: <[email protected]>
Sent: Tuesday, August 18, 2009 9:17 PM
Subject: LF: 500kHz qrg range
Hi!
For some hours now I'm sitting in front of the computer, modelling a new
and of course much much nicer :) preselector-filter for 500kHz. With a
3-inductor nodal capacitor-coupled bandpass, a 12kHz passband seems to be
a good tradeoff beetween insertation loss (2-3db), passband ripple (1db)
and shape (-24db at 518KHz, -43db at 531kHz).
So far I haven't noticed any transmissions below 500.000kHz (SK6RUD) and
above abt. 507kHz (Gus' SSB-Tests).
So I ask myself and now You :) , would You say it's important to keep the
full rx range from 495kHz to 510kHz and pay the price of a worse stopband
attenuation, or do You think, it's unlikely to hear any transmission at
the band corners?
vy73
Dennis
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