[ARC5] 75 Mtr to LF Converter - Ideas?

[Mike Feher]

Dave -

I would suggest changing the simple input lowpass filter to an elliptic
bandpass filter with sufficient attenuation in the image band. So, depending
on which 200 KHz segment of 75 meters you chose, you can design the BPF to
be centered on it remembering that the image will be 2 times the IF
frequency away, which in this case will vary from 400 KHz to 800 KHz.
Elliptics have a very sharp transition band and a good deal of attenuation
in the stop band, depending on the number of section you choose. 73 - Mike

 
Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960
 
 

-----Original Message-----
From: arc5-bounces at mailman.qth.net [mailto:arc5-bounces at mailman.qth.net] On
Behalf Of David Stinson
Sent: Tuesday, January 11, 2005 1:07 AM
To: ARC5 at mailman.qth.net; Boatanchors
Subject: [ARC5] 75 Mtr to LF Converter - Ideas?

I've uploaded a diagram, formated for printing, of a simple
converter I built to receive 75 meters on a Beacon Band
(200-400 KC) receiver.
It is at:

http://home.mindspring.com/~arc5@ix.netcom.com/convertr.jpg

It works, but images are a problem with that low IF, of course.
I didn't hope to eliminate them with this simple design,
only minimize them.  But they are more annoying than I expected.
The net is full of people smarter than me.
May I ask for your suggestions?
Thanks.



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