ATX PLT OF A CESSNA 208B CARAVAN WAS INFORMED BY TWR CTLR DURING A BACK COURSE LOC APCH THAT A LOW ALT ALERT WAS RECEIVED JUST OUTSIDE OF THE FINAL APCH FIX. HE IMMEDIATELY CLBED BACK TO THE TRANSITION MINIMUM ALT. HOWEVER; HIS COMMERCIAL CHART DEPICTED THE LOWER ALT AT WHICH HE HAD DSNDED AS THE MINIMUM ALT FOR THE FINAL APCH FIX.

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I WAS VECTORED TO INTERCEPT THE LOC BACK COURSE OUTSIDE FRITS INTXN AT 5200 FT. AROUND 10 ILBB DME; I STARTED MY DSCNT FROM 5200 FT TO 4800 FT. APPROX 6 OR 5 ILBB DME THE CTLR (I BELIEVE I WAS NOW ON THE TWR) NOTIFIED ME HE WAS RECEIVING A LOW ALT ALERT. I CHKED MY ALT AND IT READ 4800 FT; AND I STARTED A CLB BACK TO 5200 FT. NOW I'M PASSING FRIER AND NOW I'M DSNDING AGAIN TO 3820 FT. I HAD GND CONTACT; BUT DID NOT HAVE RWY ENVIRONMENT IN SIGHT. I WAS 2 DOTS R OF COURSE AND CORRECTING AND THE 'RABBITS' CAME IN VISUALLY AT ENZIE AND I LANDED WITHOUT FURTHER INCIDENT. AFTER TAXIING TO THE RAMP I ASKED THE TWR WHAT ALT THEY THOUGHT I SHOULD BE AT BTWN FRITS AND FRIER AND I WAS INFORMED THAT I NEEDED TO BE AT 5200 FT. AS YOU CAN SEE; THE APCH PLATE CLRLY SHOWED 4800 FT IS THE ALT. BY HAVING TO RECHK MY APCH PLATE AT THE FINAL APCH FIX; MADE FOR EXTRA WORKLOAD AT A CRITICAL TIME OF THE APCH. I CLBED BACK TO 5200 FT; BECAUSE I WOULD RATHER BE ALIVE; HIGH; 'THAN BE DEAD RIGHT.' I TURNED THIS INFO OVER TO OUR SAFETY DIRECTOR AND SUGGESTED HE CHK WITH COMMERCIAL TO SEE IF THERE IS A MISTAKE ON THE APCH PLATE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT OTHER ATX; AND OTHER COMPANY PLTS; HAVE ALSO GOTTEN A LOW ALT ALERT WHEN MAKING THAT SAME APCH DOWN TO THE CHART DEPICTED 4800 FT ALT. THEREFORE; WHEN THE CTLR STATED THAT THEY SHOULD BE AT 5200 FT IT SEEMED REASONABLE DUE TO THE ALT ALERTS. THERE ARE 2 HIGH XMITTING ANTENNAS JUST OFF TO THE L OF THE FINAL APCH COURSE WHICH PROBABLY CAUSES THE ALT ALERTS. HE ALSO CHKED THE GOV CHART AND FOUND IT TO SHOW THE 4800 FT.