[Elecraft] SSB TX signal mystery SOLVED !!!

[Ken G3WCS]

Cyberia wrote:
> Is your KSB2 manual revision E (July 20, 2004)??
> 
> If so, then you need to carefully examine the notes at the top of the table
> for the ICOM mikes. The note at the top of the table says NOT to connect pin
> 2 unless the MIC is pre-amplified. It says to connect AF (pin1) to 5V
> through a 10K resistor for HM-12 (your MIC) or 820 Ohms for HM-7.

Yes it is Rev E and it says, to quote "Do not connect pin 2 unless mic 
has internal preamp".

My mic does have an internal preamp and therefore according to the table 
pin 2 would appear be the logical choice.

OTOH a dynamic moving coil mic, such as the early Kenwood models which 
have the mic insert directly connected between pin 1 and earth do not 
have an internal preamp and do not require the 5v being presented via a 
resistor.

What I think the table is referring to is that some later mics have the 
preamp voltage fed up a dedicated wire connected to pin 2. In my older 
mic the signal cable (pin 1) doubles as signal and preamp voltage carrier.



73,

Ken.

-- 

Ken G3WCS <ken at g3wcs.com>
IO83rh : Cheshire : NW England
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