455kHz SSB Exciter

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Re: 455kHz SSB Exciter

Post by Admin on Sun Feb 03, 2013 3:36 pm

The ladder filter gives a more flat response and is particularöly useful for wider bandwidths. For SSB operation you only really need three of your crystals in a ladder formation, but that may be a bit too much. Try with three crystals, but if you find the bandwidth is too wide then you can always chop it down to two.

It is also interesting that crystals always deviate from the marked frequency, depending on the manufacturer and the process used. You may find three consecutive with a centre, +850 and -850, which will give you a perfect response for SSB.

If they came from a crystal synthesise then the chances are that they are fairly accurate, although they may have aged somewhat (crystal synthesis was popular 50 years ago).

BR Harry

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455kHz SSB Exciter

Post by John on Sat Jan 19, 2013 10:34 pm

I have been looking at the design for the HF SSB transmitter, and have found 9 crystals from 420 to 429kHz in 1kHz steps in my junk box, probably from a scrapped crystal bank synthesizer. How does the 2 crystal lattice filter compare with a ladder filter, and is it usable on receive as well?

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