[Elecraft] MD2 resistor mod - a different approach?

[W3FPR - Don Wilhelm]

Tom and all,

There is a solution to using a mic requiring the 5 volts (through a 
resistor) and switching to a mic that does not need it which does NOT 
require the resistor to be in the mic plug.

Wire the resistor at the mic jack between pins 5 and 6 (pin 5 = FUNC which 
is not used), then in the mic plug for the microphone(s) needing the 5 
volts, add a jumper from pin 5 to pin 1.  The mic jack will have only AF on 
pin 1, and will have +5 volts through the resistor on pin 5.

When wired this way, your Elecraft mic will work on other K2s wired for the 
standard Elecraft mic, but another standard Elecraft mic will not work on 
your K2.

Additional note - if NONE of your mics have the UP and DOWN buttons 
implemented, you can use pins 3 and 4 for any purpose you wish - including 
piping the +5 volts on one of these pins instead of pin 5.

73,
Don W3FPR


----- Original Message ----- 

I want to be able to switch between my MD2 mic which needs DC applied to the 
AF line and my Heil Proset Plus headset which doesn't.

I'm not sure I could fit the resistor that comes with the MD2 inside the 
female connector at the mic side so I'm looking into connecting pins 6 and 1 
together in the female mic connector and putting the resistor in  SERIES 
with the 5 VDC line going to pin 6 at the male end of the jack.

When the MD2 is plugged in the AF line would get DC applied through the 
dropping resistor in the 5 volt line.   When I plug in the Proset Plus pin 1 
is just audio and no DC applied.

Does anyone see a problem with doing it this way?   I know you won't be able 
to pull a lot from the 5 volt line after this mod but I don't plan on 
powering anything else off of the mic connector.    Also...I would not be 
able to plug my mic into someone else's K2 as it would put the unlimited 
5VDC line directly to my mic element.   I practice safe microphoning and 
never insert my mic into any other K2 except my own so I'm not concerned in 
either case.

Comments?  Suggestions?

Tom K2TA
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