KEXP's streaming archive. You'll have to do you some manual navigation from here. Choose
show type--Blues, Country, Roots then click GO
Now Johnny Horn's show, Preachin the Blues is top of the list. Click it.
Now Johnny's show only has the last two shows in the archives at any one time, so it is in your best interest to listen regularly. For those who want is live stream, it's 9 am to 12 pm Sundays (PDT). Not to be missed. As good as church, probably better.
Sorry to bust your wish, Griff.