On Jun 26, 11:34*am, wrote:
On Jun 26, 3:32*am, Paul Keinanen wrote:
why would anyone use the receiver CW filters

Probably a bit narrower than what I had in mind … *I'm currently
looking
at 500 KHz wide SAW filters.

As a rough guesstimate, the group delay in a 500kHz wide filter will
be 1/500,000 secs, or 2.0 microseconds. Now, depending on shoulder
steepness the change in group delay might get to 2, 3, maybe even 5
times 2.0 microseconds. But even at 20 microseconds I don't think any
of the HF digital modes you mentioned would be impacted.

Most of my comments regarding group delay and ringing in filters were
oriented towards narrowish (few kHz or less) filters.

Wow, a HF receiver with a 500kHz SAW filter after the mixer. I don't
have a clue what you're doing! I thought we were talking about HF
receivers for common bandwidths!

Tim N3QE