ACR HVT LOSS OF COM DURING RADAR VECTOR FOR ILS 28R AT PDX. PIC SAW LIGHTS AFTER PASSING LOCALIZER AND ATTEMPTED TO DESCEND AND STAY VFR. FO WAS CONCERNED ABOUT ACFT POSITION AND ADDED POWER TO INITIATE A CLIMB. PIC CONTINUED CLIMB TO SAFE ALT UNTIL RADIO COM WAS REGAINED.

Narrative

WE HAD BEEN GIVEN AN 060 DEG HDG AND 3000' VECTOR TO ILS 28R AT PDX AND WERE #2 FOR THE APCH. AS WE APCHED CLOSER TO THE LOC THE F/O AND MYSELF BEGAN TO WONDER WHY WE HAD NOT BEEN GIVEN A NORTHERLY HDG FOR THE ARPT. THE F/O WAS GETTING CONCERNED ABOUT THE TERRAIN CLRNC. I HAD NOT BECOME TOO UPSET OVER THIS BECAUSE ATC HAD GIVEN ME 3000' ALREADY WELL BELOW THE MINIMUM SECTOR ALT AND I ASSUMED THAT THE 3000' WOULD PROTECT ME IN THE AREA AROUND THE LAKER (LOM) AS DEPICTED. HOWEVER; AS WE GOT CLOSER I THOUGHT 'THIS GUY (ATC) IS GOING TO GIVE ME A HELL OF A TURN TO INTERCEPT; MAYBE HE PLANS ON RUNNING ME THROUGH AND BACK ONTO THE LOC DUE TO THE OTHER TFC.' AT THIS POINT THE F/O WAS QUITE CONCERNED ABOUT OUR LOCATION AND POS RELATIVE TO THE TERRAIN AND SAID THAT WE WERE THROUGH THE LOC. AT THIS TIME I HAD FULL DEFLECTION UP ON MY LOC WHICH WAS TUNED AND IDENTIFIED ON MY SIDE. THE LOM WAS ON MY ADF AND THE F/O HAD HOOD VOR ON HIS SIDE. THE ADF SHOWED I WAS ALMOST ON THE LOC AND THE OMEGA SHOWED APPROX 15-18 DME TO THE FIELD. I TOLD HIM TO CALL AND ASK IF THEY WERE GOING TO TAKE US THROUGH THE LOC OR WHAT. AS THE F/O WAS TRYING TO ESTABLISH CONTACT WITH ATC I TOLD HIM TO TRY THE TWR; GND; ANYONE AND TO TRY THE HF'S. AT ABOUT THIS TIME I BROKE OUT INTO VFR CONDITIONS AND COULD SEE LIGHTS BELOW. I TURNED W AND DESCENDED RAPIDLY IN AN EFFORT TO MAINTAIN VFR CONDITIONS WITH THE THOUGHTS OF CONTINUING TO THE FIELD VFR. AT THIS SAME TIME HE REMINDED ME AGAIN OF HIS CONCERN FOR THE TERRAIN AND THAT WE WERE ON THE N SIDE OF THE LOC. I DO NOT KNOW EXACTLY HOW FAR TO THE N OF THE LOC I GOT AS I WAS LOOKING OUTSIDE AND DSNDING TRYING TO STAY VFR. I THOUGHT I WOULD BE SAFE TO DESCENDED TO 2000 OR 2500' FIGURING THAT THE 3000' VECTOR ALT WOULD PROVIDE AT LEAST 1000' OF OBSTRUCTION CLRNC. ABOUT THIS TIME I BECAME UNEASY DUE TO OUR DISTANCE FROM THE FIELD AND DECIDED TO CLB TO 6200' AS I WAS NO LONGER GOING TO BE ABLE TO MAINTAIN VFR. (I CHOSE 6200' MERELY BECAUSE I COULD NOT REMEMBER EXACTLY THE MINIMUM SECTOR ALT FOR THIS AREA; BUT KNEW FROM APCH PLATE THAT 6200' WOULD CLR ALL OBSTACLES.) I PROCEEDED TO BATTLEGROUND VOR. THEN MY INTENTIONS WERE TO DESCENDED TO 4000' AND HOLD AS DEPICTED ON THE MISSED APCH PROC. I HAD CALLED FOR THE ENGINEER TO GIVE ME AN ENDURANCE ON FUEL AND KNEW I COULD HOLD FOR APPROX 2 HRS TO TRY TO SORT THE PROB OUT. AT THIS TIME I EITHER NOTICED OR WAS TOLD THAT WE WERE NOW SQUAWKING 7500 INSTEAD OF THE 7700 THAT WE HAD IN. I QUESTIONED THE 7500 SQUAWK. NO ONE SAID ANYTHING AND THE F/O ASSURED ME THAT THAT WAS LOST COM AND AT THE MOMENT I WAS MORE CONCERNED IN GAINING ALT AND PROCEEDING TO BATTLEGROUND VOR; SO I ACCEPTED IT. LATER ON THE GND WHEN TALKING TO ATC ON THE PHONE I REMEMBERED 7600 WAS THE PROPER SQUAWK. AS WE APCHED BATTLEGROUND WE STARTED RECEIVING ATC ON 121.5. THEY INSTRUCTED US TO MAINTAIN 4000' AND TURN TO A HDG I BELIEVE OF ROUGHLY 100 DEGS. I TOLD THE F/O TO ASK FOR THE MINIMUM ALT AVAILABLE SO WE COULD PROCEED VFR TO THE FIELD IN CASE OF ANOTHER LOSS OF COM. I TOLD THE F/O TO INFORM ATC THAT IF WE LOST COMS AGAIN THAT WE WOULD USE THAT ALT TO STAY VFR AND PROCEED VISUALLY TO 28R. THE RADIO WAS AGAIN CUTTING IN AND OUT AS ATC TRANSMITTED TO US. WE REMAINED ON 121.5 AND LANDED ON 28R W/O FURTHER INCIDENT. CAUSE OF THE PROB: I BELIEVE IT WAS DUE TO A FAULTY RADIO PANEL AT THE F/E STATION WHICH SOMEHOW BLOCKED ALL INCOMING TRANSMISSIONS. WAYS TO PREVENT RECURRENCE: OBVIOUSLY NO ONE CAN PREVENT A MECHANICAL MALFUNCTION; HOWEVER; I THINK A COUPLE OF THINGS MIGHT BE STRESSED OR IMPROVED. FIRST; FROM A PLT'S VIEWPOINT AS I AM NOW VERY AWARE; I FEEL ALL PLTS SHOULD INQUIRE EVEN WHEN #2 FOR THE APCH OR WHATEVER OF THE CTLR'S PLAN ON DISTANCE HE PLANS TO USE FOR TURNS TO INTERCEPT AND TURNS TO FINAL IF DISTANCE FROM THE FIELD ON DOWNWIND VECTOR BEGINS TO EXCEED 5-8 MI. TO NOT BE LULLED INTO BELIEVING EXTENSION IS FOR SEP OF TFC. SECONDLY; FROM AN ATC VIEWPOINT; HE OBVIOUSLY DID NOT EXPECT A TOTAL LOSS OF COM ON THE HDG AND ALT HE GAVE ME. IN THIS SITUATION ON A DOWNWIND VECTOR WHEN NOT CLRD FOR THE APCH BELOW THE MINIMUM SECTOR ALT I FEEL THAT ATC SHOULD ADVISE THE PLT HOW FAR FROM THE FIELD HE PLANS TO TAKE HIM BEFORE TURNING HIM INTO THE LOC TO INSURE SEP FOR THE TFC AHEAD OF HIM ON THE APCH IN CASE OF LOSS OF COMS. ESPECIALLY WHEN TERRAIN IS A FACTOR. SUPPLEMENTAL INFORMATION FROM ACN 81754: I ADVISED THE CAPT TO TURN LEFT AND INTERCEPT THE ILS COURSE. DURING THE LEFT TURN THE CAPT STARTED A DSCNT. I TOLD THE CAPT TO CLB INSTEAD AND ADVISED THERE WERE MOUNTAINS IN THE AREA. THERE WAS NO IMMEDIATE REACTION AND I PUSHED THE THROTTLES FORWARD AND PULLED BACK ON THE YOKE TO INITIATE A CLB. DURING THE CLB THE CAPT REGAINED CTL. I PUT 7700 IN THE TRANSPONDER. AFTER A MINUTE I ASKED WHAT LOST COM WAS AND RECEIVED 7500 AS THE ANSWER. LATER WE REALIZED THAT 7600 WAS CORRECT.