[Elecraft] K3s rear mic connector and shure SM58.

[Joe Subich, W4TV]

It doesn't matter if the input is balanced or unbalanced.  The shield
and mic return should *never* be connected together.  The shield is
connected to the case of the microphone *not* a signal (mic -) line
and connecting shield to mic - simply adds common mode noise and hum
to the low level mic (-57 dBV) signal.

If you want to connect a 6 foot radial to the mic input of your rig,
be my guest, but don't suggest it to others due to the potential for
hum, RFI and other garbage.   The only case where the shield and
mic - is tied together for unbalanced inputs is where the mic (-)
is *properly* returned to the chassis *at the input* and that is not
the case with the K3/K3S *or any other transceiver that I know of*.

73,

    ... Joe, W4TV


On 10/6/2017 8:58 AM, Bob McGraw K4TAX wrote:
> Joe.    He is using the rear panel MIC input.  It is unbalanced.
> 
> Bob, K4TAX
> 
> 
> Sent from my iPhone
> 
>> On Oct 6, 2017, at 7:50 AM, Joe Subich, W4TV <lists at subich.com> wrote:
>>
>>
>>> Pin #1 & #3 to ground
>>
>> Pins 1 and 3 should *never be tied together*.  If your transceiver has
>> a balanced input *or* a *separate* case/chassis connection, connect
>> pin 1 (shield/mic case) to the case/chassis connection (ideally to the
>> *shell* of a Foster mic jack that is bolted securely to the metal case
>> of the transceiver).
>>
>> If your transceiver does not have a separate case/chassis connection
>> (the K3/K3S rear mic jack *does not*) leave pin 1 disconnected
>> (floating).
>>
>> 73,
>>
>>    ... Joe, W4TV
>>
>>
>>> On 10/5/2017 9:30 PM, Bob McGraw K4TAX wrote:
>>> No preamp required.  Set the Mike gain via the menu to high. Easy to wire the mike XLR to an unbalanced circuit.   Pin #1 & #3 to ground and Pin #2 to MIC high.  See page 55  of the manual [MIC SEL] for details.
>>> If you close talk the mike it will be bottom end heavy. Typically no closer than 4" will be OK.  Move in closer and the bottom end comes up, back away and the bottom end falls off. This is due to the proximity effect of they type dynamic mike.
>>> Otherwise, they sound quite good/.
>>> 73
>>> Bob, K4TAX
>>>> On 10/3/2017 1:50 PM, Stewart wrote:
>>>> Is anyone using a Shure SM58 mic with their K3s? If so are you using a preamp? My O'scope shows that the mic and cable are good but level is pretty low.
>>>>
>>>> I don't get anything with the mic connected to the rear mic jack. Config is set to rp l , bias off. I tried mic gain from 0 - 100.
>>>>
>>>> K3s is new so I may be missing some menu item.
>>>>
>>>> Regards,
>>>>
>>>> Stew ke4yh
>>>>
>>>>
>>>>
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