SM7HKM/Bruno



Radio Operatör R136 VÄSTERVIK.

Tips från SM7HKM Bruno
Modification of the new ICOM HM-36 Microphone
The first step is to figure out what type you have, the old or the new one.
The old version of the HM-36 has always sound good and has an electret
microphone with three connections.
It is recognized by the three wires, red, black and shield. If it looks this way
you got the old version and no modification is needed. This microphone is
 marked 'MADE IN JAPAN' or no marking at.
 The first step is to figure out what type you have, the old or the new one.

 The new HM-36 entered the market at the end of 2007 and beginning of 2008. This
 new type has too less of the higher frequencies and too much of the low ones. On the
 back side of the microphone you can find 'MADE IN CHINA'.
The new type only have too wires connected to the element.
It is simple to modify the new type to sound as the old one.

 1. Remove R1, 1 kOhm and C2, 10 µF.
 2. Change C1 from 0.22 µF (sometimes schematic shows 0.33 µF) to 0.01 µF (equal to 10 nF or 10 000 pF)
These components are marked on the circuit board and easy to locate.
The C1 can be replaced with a tantalum or ceramic capacitor

 
 

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