If I recall correctly, and there is a chance I may not as my memory does 
tend to play small games with me sometimes:
 when I built the box I checked for continuity between the audio ground pin 
and the chassis ground pin on the radio mike socket.  There was full 
continuity which leads me to believe they are the same.
I suspect there are separate pins because it's easier to solder a single 
wire to a pin instead of two wires to the same pin...so they just tie the 
two grounds together in the radio's socket or somewhere beyond that point.
I kept them separate as well, but I don't know if you absolutely have to 
even when running a balanced mike line.
Unless there are some low value resisters or small caps to ground on the 
mike ground that are too small to effect a continuity reading.  My meter I 
think reads continuity below a couple ohms.
Or, the mike ground could be switched to a different path when the PTT is 
enabled, I didn't check that.

I initially had a bit of RF getting into my unbalanced chunk of XLR mike 
cable that I used for the project.  I simply wrapped the 3 feet of excess 
around the desk stand poll and it went away.
I use a round base desk stand with an 8 inch poll that extends out to about 
14 inches...I have it all the way down, and a 13 inch flexible goose neck. 
My operating position is such that that stand needs to be back on the desk a 
bit, so I needed the goose neck to extend out quite a bit.  It gets a little 
wobbly with a mike on the end of it, but I've got something on the back of 
the base plate to keep it stable...one could easily drill a couple holes and 
screw the base plate down to the desk.
Or, I could get a nicer boom arm that would be much more balanced.
Anyway, at the end of the day, I don't think the grounds on the mike socket 
are separate so you can tie them together or use the main ground for the 
audio line if you want.

Has anyone here used the audio in on the accessory jack for microphone 
audio?  it bypasses the mike preamp and if you run an external pre of some 
kind (like the art mp1), apparently the audio is far better than going into 
the mike jack.
Though, the mike preamp in the radio apparently does boost some frequencies 
in the voice range like between 400 and 1Khz...not sure which frequencies or 
their Q or gain factors, but some prefer that sound over a flatter sound.

73
Colin, V A6BKX
----- Original Message ----- 
From: "Michael Thurman" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Sunday, May 12, 2013 2:49 PM
Subject: Re: Building a PF key box for Kenwood


>I missed some of this thread, but I always kept the audio ground =
> separate because if memory serves, the mic input is actually balanced or =
> can be. a friend of mine wired up an xor mic adaptor so I could use my =
> audio technics mic with my ts2000. unfortunately the adaptor  wore out, =
> I need to have him make me another one
>
> On May 11, 2013, at 11:32 PM, Butch Bussen <[log in to unmask]> =
> wrote:
>
>> Thanks very much.  Do you keep the audio ground separate?  I always=20
>> wondered why Kenwood did that.
>> 73
>> Butch
>> WA0VJR
>> Node 3148
>> Wallace, ks.
>>=20
>>=20
>> On Sat, 11 May 2013, Steve Forst wrote:
>>=20
>>> Butch,
>>>=20
>>> Looking at the  end of the  mic plug (looking at the holes), notch
>>> pointing  down (6 o'clock position), pin 1 is to the left of the =
> notch
>>> (7 o'clock) then clockwise around to pin 7 which is  just to the =
> right
>>> of the notch (5 o'clock).  Pin 8 is dead center.
>>>=20
>>> I guess there is always  a chance of some variation, but in general =
> for
>>> the  Kenwood's:
>>> pin 1 =3D mic audio
>>> pin2 - ptt
>>> pin 3 - down
>>> pin4 - up
>>> pin 5 - 8 vdc
>>> pin 6 - not used in the 590, but may provide speaker audio in some =
> rigs
>>> pin 7 - mic ground  (may be a braid wire)
>>> pin 8 - ground
>>>=20
>>> 73, good luck with the new toy, Steve  KW3A
>>>=20
>>> On 5/11/2013 11:07 PM, Butch Bussen wrote:
>>>> How are the pins counted on the 8 pin cable?  Lokoking from wich end =
> of
>>>> the plug?
>>>> 73
>>>> Butch
>>>> WA0VJR
>>>> Node 3148
>>>> Wallace, ks.
>>>>=20
>>>>=20
>>>> On Sat, 11 May 2013, Steve Forst wrote:
>>>>=20
>>>>> After putting this off for a number of years, I finally decided to =
> build
>>>>> a box to give me more PF keys for the 590.  Turns out I had all I =
> needed
>>>>> right here.   It's not completely complete yet, since I have to =
> drill
>>>>> holes for switches, but it has  been  wired up temporary and seems =
> to work.
>>>>>=20
>>>>> Main component is an old MFJ TNC to radio interface.    The KAM is =
> long
>>>>> gone and I clipped the 13 pin DIN off it some time ago, but it has =
> an 8
>>>>> pin round mic jack on the front and  8 wire mic cable  with plug =
> coming
>>>>> in the rear.
>>>>>=20
>>>>> Also had the needed switches and other odds and ends  laying =
> around.
>>>>> One thing I learned is that the 590 will let you change the UP/DOWN
>>>>> buttons into additional PF keys,  so I will wind up with 6 pf keys =
> on
>>>>> the box and the original 2 on the radio.
>>>>>=20
>>>>> Anyone using a microphone with UP/DOWN buttons can reassign them as =
> PF
>>>>> keys if you don't need the UP/DOWN function.
>>>>>=20
>>>>> Also added an RCA jack for PTT, and a 1/8 jack for mic input, since =
> the
>>>>> mics I use  all the time have  1/8 plugs.   Maybe later I'll add  a =
> mic
>>>>> input for  a condenser mic, using the 8 vdc found  on pin 5 of the  =
> 8
>>>>> pin cable.
>>>>>=20
>>>>>=20
>>>>> 73, Steve KW3A
>>>>>=20
>>>>>=20
>>>>=20
>>>>=20
>>>>=20
>>>=20
>>>=20