A DC9-30 IN CLB AT 14000 FT DIVERTED DUE TO A SUDDEN LOSS OF CABIN PRESSURE DUE TO RADIO FREQ INTERFERENCE CAUSING THE DIGITAL PRESSURE CTLR TO MALFUNCTION.

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CABIN PRESSURE AUTO FAIL LIGHT ILLUMINATED DURING CLB THROUGH 14000 FT. FOLLOWED BY A CABIN PRESSURE BUMP AND CABIN VERT CLB INDICATION OF OVER 2000 FPM CLB. CABIN PRESSURE ANNUNCIATOR LIGHT ILLUMINATED AND SHORTLY AFTER THE CABIN OXYGEN ON. PERFORMED CABIN PRESSURE AUTO FAIL AND CABIN PRESSURE LOSS PROCS. UNABLE TO REGAIN AUTO PRESSURE CTL. RETURNED TO DEP ARPT WITH PRESSURE SYS IN MANUAL MODE. DUE TO SMALL ALT CHANGE REQUIRED; DID NOT ACCOMPLISH EMER DSCNT. CABIN STATUS WAS NORMAL AND EMER WAS NOT DECLARED WITH ATC. THE DIGITAL PRESSURE SYS INSTALLED IN THIS ACFT IS RELATIVELY NEW. SYS INSTALLATION; DESIGN AND RELIABILITY MUST BE QUESTIONED TO PREVENT A RECURRENCE OF THIS EVENT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR SAID THE ACFT WAS A DC9-30 WITH P&W JT8D-9 ENGS. THE RPTR STATED THIS AIRPLANE WAS 1 OF 2 OR 3 AIRPLANES IN THE CARRIER'S FLEET FITTED WITH NEW DIGITAL AUTO PRESSURE CTLRS WITH AIR DATA COMPUTER INPUTS. THE RPTR SAID THE DEPRESSURIZATION WAS SUDDEN AND COULD NOT BE CTLED IMMEDIATELY WITH THE MANUAL CTLR AS IT TOOK ABOUT 75 SECONDS TO GAIN CTL MANUALLY. THE RPTR SAID THE AIRPLANE WAS OTS FOR SEVERAL DAYS AND ALL SYS OPERATED NORMALLY. THE RPTR STATED IT WAS THEN DISCOVERED THE AUTO PRESSURE CTLR WAS AFFECTED BY RADIO FREQ INTERFERENCE WHICH WAS EMITTED BY DISBONDED DME AND TCASII ANTENNAS. THE RPTR SAID MAINT RELATED TO THE RPTR OF ANOTHER INCIDENT OF THIS TYPE THAT OCCURRED IN GERMANY. THE RPTR SAID THE MANUFACTURER OF THE AUTO PRESSURE CTLR IS UNKNOWN.