This got blocked. The SCR-274-N parts list gives 3500, 4600, 6200 and 8000 KC. I have also had 5205 and 5500 DC-8's. The ATA/ARA manual adds 2500 KC. Robert Downs - Houston <http://www.wa5cab.com> (Web Store) <wa5cab at cs.com> (Primary email) <wa5cab at houston.rr.com> (Backup email)