Topband: banpass filters & analyzer

[Telegrapher9 at aol.com]

Mike,

here is a link to a good filter design program that is free: 
http://www.aade.com/filter32/download.htm

This will let you explore some filters. I use this program at work and it 
saves lots of time. 

 The 90-deg coax stub looks a bit to 1.8MHz though. Using RG213 that is 
90-deg at 1.4 MHz, the impedance of the filter, when terminated into 50 ohms, is 
1.7 +j0 ohms  at 1.4 MHz and 10 +j18 ohm at 1.8 MHz. Making the stub 277 deg 
gives 5 +j5 ohms and 45 +j3 ohms. That's 13 dB of attenuation at 1.4 MHz. 

    Dave WX7G