[Tech-Assist] Convert Harris FM5K to SS IPA

[Alan Kilgore]

It is not quite that simple. Using a large exciter instead of having 
separate IPA is not the issue; it is matching the input to PA.

The PA does not have a 50 Ohm input. There is high-impedance 
interstage coupling between the IPA and PA. The tube IPA is built 
directly under the bottom of the PA cabinet. There is no cable 
between the cabinets. IIRC, only the FM2.5 models had 50 Ohm 
interstage cabling,

So, someone still had to add a big honking swamping resistor or 
otherwise modify the PA grid input.

____________________________________
Alan Kilgore, CPBE
WRVM Chief Engineer

At 08:43 PM 3/31/2012, you wrote:
Here's another idea:

I haven't converted any myself, but I know of a couple FM5K and 10K's 
that had their IPA's removed altogether.  Just replaced with a 300 
watt exciter and went straight to the PA input.

Kevin