Microphone Setup

[Elecraft mailing list]

Is there an FAQ for microphone setups for the K3(S)?

Particularly, I am looking how to set up the Heil PR-781 on the K3,
including the menu setup.

TIA,

'73 de JIM N2ZZ


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[Jim Brown-10]

On Tue,11/3/2015 7:44 PM, James F. Boehner, MD via Elecraft wrote:
> Is there an FAQ for microphone setups for the K3(S)?

Yes. It's called read the manual.

73, Jim K9YC
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[Richard Fjeld-2]

James,

Sorry about that.  I'd be glad to help you.  You can email me off-line
if needed.

It's been a few years, but the review would do me good. I can remember
this; at the time, it was the same as a Kenwood except for one
wire/pin.  The bias battery had
me wondering as I recall.  But it is easy to understand, once explained.
I like the arrangement that Elecraft uses.

Dick, n0ce


On 11/3/2015 9:59 PM, Jim Brown wrote:
> On Tue,11/3/2015 7:44 PM, James F. Boehner, MD via Elecraft wrote:
>> Is there an FAQ for microphone setups for the K3(S)?
>
> Yes. It's called read the manual.
>
> 73, Jim K9YC
> ______________________________________________________________

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[Don Wilhelm-4]

Dr. Jim,

There is no FAQ that I am aware of.
Actually the information is pretty basic.  Microphone elements come in
two basic types - Electret and Dynamic.
The Electret types need a DC bias applied to the AF line.
The Dynamic elements should *not* have bias applied or they will be
distorted.

The other thing that often causes confusion is the mic plug pinout. The
mic plug wiring must match the pin arrangement used in the transceiver,
and that information is shown in the transceiver manual.  In the case of
the Elecraft K3 and K3S, the 8 pin mic pinout differs only from that
used by Kenwood in that the use of pins 5 and 6 are reversed.  Since
most Kenwood unamplified dynamic microphones do not use pins 5 and 6,
most all Kenwood dynamic microphones will work directly with the K3 and K3S.

Heil microphones normally use a 4 pin XLR as a generalized connector
*and* use an adapter or special cable to change that XLR connection to
that required for the transceiver.  The adapter to be used with the K3
and K3S is the one for the Kenwood (which has a red band).

Heil microphones come in both the dynamic and the electret types,
although most are dynamic.  If the microphone is designated with a "-iC"
or "-K2" it is an electret type.

A lot of information on microphones and transceiver connections can be
found at http://homepage.ntlworld.com/rg4wpw/date.html.  G4WPW has done
an excellent job of collecting information about microphones, mic
pinouts and even schematics.

In your particular case with the Heil PR-781, use the Kenwood cable
(Heil CC-1XLR-K) with that microphone and make certain the bias is
turned off.
I believe that microphone has a rather low output, so you may have to
use the high range for the mic gain.
So - the K3(S) MIC SEL menu should be set to "FP H".
Set the mic gain as described in the K3 manual - first set compression
to zero, then adjust the MIC GAIN until you see 5 to 7 bars illuminated
on the ALC meter (that can be done in TX TEST so no RF is produced).  
Then bring the compression up to your tastes, usually in the 3 to 6 dB
range.

73,
Don W3FPR


On 11/3/2015 10:44 PM, James F. Boehner, MD via Elecraft wrote:
> Is there an FAQ for microphone setups for the K3(S)?
>
> Particularly, I am looking how to set up the Heil PR-781 on the K3,
> including the menu setup.
>
>

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[Charlie T, K3ICH]

If you ever wondered why a bias voltage can cause
distortion in a dynamic microphone element, just
consider what happens when you connect a DC source
to a speaker.  The voice coil move in one
direction depending on the polarity.  Now think of
a dynamic mic element doing the same thing.  After
all, electrically, the element and speaker are
essentially the same.   The DC bias causes the mic
element's static condition to be physically moved
from its normal resting position, so the output
waveform will not be an accurate electrical
representation of the audio wavefront arriving at
the element.

73, Charlie k3ICH





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[Bob McGraw - K4TAX]

Jim:

I use the PR -781 on my K3S with excellent results.

 From the MENU scroll to  MIC SEL - choose FP.H meaning front panel
high.   {See page 55 of the K3S manual.}

 From the MENU select TX EQ  {See page 56 of the K3S manual.}
set frequencies as follows
#1  50 Hz     -16
#2  100 Hz    -8
#3  200 Hz     0
#4  400 Hz     0
#5  800 Hz     0
#6  1600 Hz   0
#7  2400 Hz   +3
#8  3200 Hz   +6

Scroll to VOX gain and set the value to 020
Scroll to ANTIVOX and set the value to 010
Exit MENU to save.

Go to the CONFIG menu and scroll to  TX ESSB   {See page 66 in the K3S
manual for details.}
Set this value to ON and  3.0
Exit menu to save.

 From the front panel:
Set the MIC gain at about 40.  This gets about 4 to 5 bars on the ALC meter.
Set the COMP at about 15.  This gets about 3 to 4 bars on the CMP meter.

Operate with a mike-to-mouth distance of about 1 fist or about 4" to
5".  If you get too close you will find the proximity effect will bring
the bottom end up a noticeable amount.

Get ready for "great audio" reports!

73
Bob, K4TAX

On 11/3/2015 9:44 PM, James F. Boehner, MD via Elecraft wrote:
> Is there an FAQ for microphone setups for the K3(S)?
>
> Particularly, I am looking how to set up the Heil PR-781 on the K3,
> including the menu setup.
>
> TIA,
>
> '73 de JIM N2ZZ


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[Jim Brown-10]

On Wed,11/4/2015 5:43 AM, Charlie T, K3ICH wrote:
> If you ever wondered why a bias voltage can cause
> distortion in a dynamic microphone element, just
> consider what happens when you connect a DC source
> to a speaker.  The voice coil move in one
> direction depending on the polarity.  Now think of
> a dynamic mic element doing the same thing.

This is one of those ideas that, while having a solid theoretical basis,
doesn't hold up once you plug numbers into the problem. That's because
the bias voltage is typically provided from a rather high impedance
source, so the bias current is too low and the sound pressure level is
too low to drive the diaphragm anywhere near its limits.

The simple fact is that it's virtually impossible to overload a dynamic
mic. One major mic manufacturer advertised that their dynamic mics could
reproduce a gunshot without distortion. It wasn't a lie -- almost any
pro dynamic mic can do that. When you hear distortion from a dynamic
mic, it's the mic producing enough output to overload the mic preamp,
and the solution is to either reduce the preamp gain or add a pad
(passive attenuator). Controls to do both are built into the mixers used
for live sound, broadcast, and recording.

73, Jim K9YC
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[Bob McGraw - K4TAX]

While I agree with Jim, K9YC on this.  Some dynamic mikes I've
encountered do use a transformer to get the voltage level from the very
low impedance Z element to a respectable output value.  Running a bit of
DC through the transformer on the secondary side could tend to cause
some DC saturation.   And transformers which are not designed to handle
DC can behave a bit odd under this condition. Other dynamic mikes I've
encountered provide an internal DC blocking capacitor to prevent this
issue, although that in itself has its issues.

Yes, with any dynamic mike being used, set the bias to the off
position.......just to be safe.    And don't worry about overloading a
dynamic mike, but do be concerned with the preamp or first analog stage
being driven into distortion.

73
Bob, K4TAX

On 11/4/2015 7:54 PM, Jim Brown wrote:
> This is one of those ideas that, while having a solid theoretical
> basis, doesn't hold up once you plug numbers into the problem. That's
> because the bias voltage is typically provided from a rather high
> impedance source, so the bias current is too low and the sound
> pressure level is too low to drive the diaphragm anywhere near its
> limits.


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[Jim Brown-10]

On Wed,11/4/2015 6:39 PM, Bob McGraw - K4TAX wrote:
> While I agree with Jim, K9YC on this.  Some dynamic mikes I've
> encountered do use a transformer to get the voltage level from the
> very low impedance Z element to a respectable output value. Running a
> bit of DC through the transformer on the secondary side could tend to
> cause some DC saturation.

Exactly right, Bob. And Don Wilhelm reminded me that some mics used with
a K2 didn't like bias. That can, of course, depend strongly on the value
of the bias source resistance.

73, Jim K9YC
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[Jim Brown-10]

On Wed,11/4/2015 6:39 PM, Bob McGraw - K4TAX wrote:
> Yes, with any dynamic mike being used, set the bias to the off position

Don Wilhelm says that some dynamic mics sold to hams DO get distorted
with bias applied. Whether it's a poor mic or a saturated transformer,
it's clearly better to turn off bias when using a ham dynamic mic.

73, Jim K9YC
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[Joe Subich, W4TV-4]

Even if the bias does not saturate the coil and cause distortion,  it
*will* reduce the output (sensitivity).  A dynamic mic typically has
a very low (< 5 mV) output level any reduction in output level is to be
avoided.

73,

    ... Joe, W4TV


On 11/5/2015 1:11 AM, Jim Brown wrote:

> On Wed,11/4/2015 6:39 PM, Bob McGraw - K4TAX wrote:
>> Yes, with any dynamic mike being used, set the bias to the off position
>
> Don Wilhelm says that some dynamic mics sold to hams DO get distorted
> with bias applied. Whether it's a poor mic or a saturated transformer,
> it's clearly better to turn off bias when using a ham dynamic mic.
>
> 73, Jim K9YC
> ______________________________________________________________
> Elecraft mailing list
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> Message delivered to [hidden email]
>

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