[RTTY] bandpass filters

[Jerry Flanders]

When I operated SO2R years ago I had bandswitching filters ahead of 
the amps and homemade stubs after. I could operate anywhere except 
within 15-20 Khz of the second harmonics.

50 ohm coax is not required for the stubs - I was using free 75.

Jerry W4UK

At 12:21 AM 3/20/2016, Jim W7RY wrote:
>George Cutsogeorge, W2VJN's, book is really great for using tuned 
>stubs (coax cable) for low notching out other bands for SO2R. I use 
>on on my 80 meter antenna to keep from getting into 40 meters.
>Something I cant do with a Dunstar filter between the exciter and amplifier.
>
>
>73
>Jim W7RY
>
>
>-----Original Message----- From: Bill Turner
>Sent: Saturday, March 19, 2016 8:15 PM
>To: RTTY Reflector
>Subject: Re: [RTTY] bandpass filters
>
>Bandpass filters at the 1500 watt level are quite expensive - around
>$400 for each band. Do the math.
>
>If you want to save some money, you can build your own.  Accompanying
>each ARRL Handbook is a CD which contains design software for high
>pass and low pass filters. By choosing the cutoff frequencies
>carefully and putting them in series, you could save a considerable
>amount of money.
>
>This particular software is especially useful because it uses standard
>value components. In fact that is the name of the program: SVC Filter
>Designer.  Here's a hint: Each filter segment can be looked at as a
>parallel resonant circuit, i.e. a coil paralleled by two capacitors in
>series. You can use a grid dip meter to carefully adjust the coil to
>resonate at the frequency given by the standard equations for
>resonance. Do each filter segment separately, then connect them
>together. You can check the final result by sweeping it with an SWR
>meter while terminated into a dummy load or a real antenna.
>
>It is also available at this website:  http://tonnesoftware.com/
>along with other filter design software and there may be others as
>well. It is well worth browsing around.
>
>73, Bill W6WRT
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