Telex Corp. has told its employees to be ready for a takeover by New York financier Asher B. Edelman. The company said that the stock market collapse has limited its options to fend off the unsolicited buyout bid. "When our stock is selling substantially less than the offer price, our stockholders may likely sell their stock to TLX Partners (Edelman) unless there is a better offer on the table," a letter signed by Telex Chairman S. J. Jatras and President G. L. Bragg said. Telex shares closed up $3.125 at $51 Friday. Edelman's offer is $65 a share.