[GE] Mastr III amplifier question

[n griggs]

I am trying to find the correct LBI for a 19D902757G12.  This is a Mastr III PA, 150.8 - 174 MHz.  I have LBI-38531 (versions A-G).......BUT......all the versions show a MMIC (U101) as the first item the RF hits (UPC1677).  The schematic shows an eight pin part.  However, the amplifier I am working on (no RF out after the fans died), has two transistors OR one transistor and a MAR IC before the M57719.  Is there a technical service bulletin concerning this change or did GE/Ericsson make the change and not document it?  Right now I am just doing simple checks (shorts, opens, fried stuff) and haven't put any RF into it yet to see where the issue is.  I know that a circulator would help on the output, especially since the antenna it was connected to, at 100 watts out, has a reflected power of approximately 20 watts.  This antenna is now being used for receive - halfway up the tower - the top antenna is now being used for transmit (reflected power of
 approximately 8 watts).  This amplifier is also odd in that it has two smaller fans mounted on the bottom blowing up across the heatsink fins as opposed to the normal larger fan mounted on the cover blowing directly onto the circuit board.    I am hoping it is just something inexpensive to repair like the 7808 or one of the transistors used to feed power to the M57719 for power control. 

As always, I thank anyone in advance for their assistance.


Neal  KC4YCM