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D 104

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CHARLES WHITE

D 104

I would like to connect a D 104 mike to the K3 but the D 104 is a 4 pin jack and the K3 is 8 pins.

I have not been able to find a 8 pin jack for the mike at either MOUSER or DIGIKEY suppliers.

Does any one use the D104 with the K3?

Any advise?

Thanks

Charlie White
K6TBB
San Diego
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k5oai

Re: D 104

I use an amplified D-104 with my K3, excellent audio reports.
I have also used an un amplified D-104, with equally good reports.

Try your local radio shack for the 8 pin jack.

8-Pin Ham Microphone Plug
Model: 274-025 | Catalog #: 274-025
$4.19

http://www.radioshack.com/product/index.jsp?productId=2062445

GB & 73
K5OAI
Sam Morgan

On 6/4/2011 12:22 PM, CHARLES WHITE wrote:

> I would like to connect a D 104 mike to the K3 but the D 104 is a 4 pin jack and the K3 is 8 pins.
>
> I have not been able to find a 8 pin jack for the mike at either MOUSER or DIGIKEY suppliers.
>
> Does any one use the D104 with the K3?
>
> Any advise?
>
> Thanks
>
> Charlie White
> K6TBB
> San Diego

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Lou Kolb

Re: D 104

You'd also be well advised, if its an unamplified D-104, to add one of the
op-amp matching circuits which can be powered from the K3. It'll make the
D-104 look into the 10 megohms or so that it likes and it will sound much
more natural. a Quic google search should yield a few of these circuits.
Lou WA3MIX
----- Original Message -----
From: "Sam Morgan" <[hidden email]>
To: <[hidden email]>
Sent: Saturday, June 04, 2011 1:30 PM
Subject: Re: [Elecraft] D 104

>I use an amplified D-104 with my K3, excellent audio reports.
> I have also used an un amplified D-104, with equally good reports.
>
> Try your local radio shack for the 8 pin jack.
>
> 8-Pin Ham Microphone Plug
> Model: 274-025 | Catalog #: 274-025
> $4.19
>
> http://www.radioshack.com/product/index.jsp?productId=2062445
>
> GB & 73
> K5OAI
> Sam Morgan
>
> On 6/4/2011 12:22 PM, CHARLES WHITE wrote:
>> I would like to connect a D 104 mike to the K3 but the D 104 is a 4 pin
>> jack and the K3 is 8 pins.
>>
>> I have not been able to find a 8 pin jack for the mike at either MOUSER
>> or DIGIKEY suppliers.
>>
>> Does any one use the D104 with the K3?
>>
>> Any advise?
>>
>> Thanks
>>
>> Charlie White
>> K6TBB
>> San Diego
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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Grant Youngman

Re: D 104

Or a simple matching transformer -- Hi-Z to Low-Z. But in either case, you can't run a naked D-104 into the K3 mic input. The element needs to see a very high impedance.

Grant/NQ5T

Sent from my iPhone

On Jun 4, 2011, at 1:45 PM, "Lou Kolb" <[hidden email]> wrote:

> You'd also be well advised, if its an unamplified D-104, to add one of the
> op-amp matching circuits which can be powered from the K3. It'll make the
> D-104 look into the 10 megohms or so that it likes and it will sound much
> more natural. a Quic google search should yield a few of these circuits.
> Lou WA3MIX
> ----- Original Message -----
> From: "Sam Morgan" <[hidden email]>
> To: <[hidden email]>
> Sent: Saturday, June 04, 2011 1:30 PM
> Subject: Re: [Elecraft] D 104
>
>
>> I use an amplified D-104 with my K3, excellent audio reports.
>> I have also used an un amplified D-104, with equally good reports.
>>
>> Try your local radio shack for the 8 pin jack.
>>
>> 8-Pin Ham Microphone Plug
>> Model: 274-025 | Catalog #: 274-025
>> $4.19
>>
>> http://www.radioshack.com/product/index.jsp?productId=2062445
>>
>> GB & 73
>> K5OAI
>> Sam Morgan
>>
>> On 6/4/2011 12:22 PM, CHARLES WHITE wrote:
>>> I would like to connect a D 104 mike to the K3 but the D 104 is a 4 pin
>>> jack and the K3 is 8 pins.
>>>
>>> I have not been able to find a 8 pin jack for the mike at either MOUSER
>>> or DIGIKEY suppliers.
>>>
>>> Does any one use the D104 with the K3?
>>>
>>> Any advise?
>>>
>>> Thanks
>>>
>>> Charlie White
>>> K6TBB
>>> San Diego
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>
> ______________________________________________________________
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> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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Jim Brown-10

Re: D 104

In reply to this post by Lou Kolb

On 6/4/2011 11:45 AM, Lou Kolb wrote:
> You'd also be well advised, if its an unamplified D-104, to add one of the
> op-amp matching circuits which can be powered from the K3.

As a pro audio engineer, I would advise trying the D104 straight into
the K3 and using TX with someone listening to you carefully on the air
before going any further.

73, Jim Brown K9YC
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Grant Youngman

Re: D 104

That would be a COMPLETE AND TOTAL waste of time. The K3 mic input Z is 600 ohms nominal per spec.

The D-104 element needs 500k minimum and better no less than 5M. Last I heard the input stage of a K3 was not a 12AU7/12AX7.

That's why Z transformation (preamp, xformer) IS required for this element

Grant/NQ5T

>>
>
> As a pro audio engineer, I would advise trying the D104 straight into
> the K3 and using TX with someone listening to you carefully on the air
> before going any further.
>
> 73, Jim Brown K9YC
> ______________________________________________________________
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P.B. Christensen

Re: D 104

In reply to this post by Lou Kolb

If an active transformer/buffer is really desired, I recommend staying away
from an op-amp circuit. A single-stage JFET transistor uses fewer parts, is
generally less susceptible to RF, and there's no voltage-divider bias needed
** -- and still have the benefit of a high-Z input and low-Z output. See my
QRZ.com page for D-104 alternatives with the K3.

Beware of Google searches on this topic. Most active transformer D-104
circuits I've seen on the web are incorrectly designed and several use
superfluous components, the exception being W8JI's design which is similar
to the one shown on my QRZ.com page.

Paul, W9AC

** Most op-amps are designed for use with bi-polar power supplies. When
used with a single-supply rail, the op-amp input must be biased such that
the output is 1/2 the supply rail with no input signal present.

----- Original Message -----
From: "Lou Kolb" <[hidden email]>
To: "elecraft" <[hidden email]>
Sent: Saturday, June 04, 2011 2:45 PM
Subject: Re: [Elecraft] D 104

> You'd also be well advised, if its an unamplified D-104, to add one of the
> op-amp matching circuits which can be powered from the K3. It'll make the
> D-104 look into the 10 megohms or so that it likes and it will sound much
> more natural. a Quic google search should yield a few of these circuits.
> Lou WA3MIX
> ----- Original Message -----
> From: "Sam Morgan" <[hidden email]>
> To: <[hidden email]>
> Sent: Saturday, June 04, 2011 1:30 PM
> Subject: Re: [Elecraft] D 104
>
>
>>I use an amplified D-104 with my K3, excellent audio reports.
>> I have also used an un amplified D-104, with equally good reports.
>>
>> Try your local radio shack for the 8 pin jack.
>>
>> 8-Pin Ham Microphone Plug
>> Model: 274-025 | Catalog #: 274-025
>> $4.19
>>
>> http://www.radioshack.com/product/index.jsp?productId=2062445
>>
>> GB & 73
>> K5OAI
>> Sam Morgan
>>
>> On 6/4/2011 12:22 PM, CHARLES WHITE wrote:
>>> I would like to connect a D 104 mike to the K3 but the D 104 is a 4 pin
>>> jack and the K3 is 8 pins.
>>>
>>> I have not been able to find a 8 pin jack for the mike at either MOUSER
>>> or DIGIKEY suppliers.
>>>
>>> Does any one use the D104 with the K3?
>>>
>>> Any advise?
>>>
>>> Thanks
>>>
>>> Charlie White
>>> K6TBB
>>> San Diego
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

Jim Brown-10

Re: D 104

In reply to this post by Grant Youngman

On 6/4/2011 12:16 PM, Grant Youngman wrote:
> That would be a COMPLETE AND TOTAL waste of time. The K3 mic input Z is 600 ohms nominal per spec.

Nominal is the operative word here. It's designed to have enough gain
for the low impedance mics commonly used with ham gear. If you study the
schematic, you see that the mic input stage of a K3 is NOT 600 ohms,
it's an opamp, which is a fairly high Z load. The input Z is at least
10K, probably more like 15K -- there's a 10K resistor in series with the
input!

> The D-104 element needs 500k minimum and better no less than 5M. Last I heard the input stage of a K3 was not a 12AU7/12AX7.

This whole issue of impedance matching in audio is widely misunderstood.
In a passive mic (that is, one that is unamplified), it mainly affects
gain and sensitivity. The high-Z D104 is a very hot mic, and the K3 has
a LOT of available gain, so you can afford to lose a lot with the
mismatch. The second way that impedance CAN affect the sound of a
passive mic is frequency response (due to stray L and C in the capsule
or output network), but the K3 has VERY good and very flexible TXEQ,
which is very likely to be able to correct for any response deviations.

> That's why Z transformation (preamp, xformer) IS required for this element

The mic input stage of the K3 is quite well designed so that it can work
very with a wide range of mics. Calling it a 600 ohm input stage is
technically WRONG and misleading (just as it misled you). Like I said, I
would try the mic first.

73, Jim Brown K9YC

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Grant Youngman

Fwd: D 104

In reply to this post by CHARLES WHITE

Sent from my iPhone

Begin forwarded message:

> From: Grant Youngman <[hidden email]>
> Date: June 4, 2011 3:12:03 PM CDT
> To: "[hidden email]" <[hidden email]>
> Subject: Re: [Elecraft] D 104
>

> 10-15k is not high enough for good performance from a D-104 element. It will sound like a squeaker at best, ir worse.
>
> Like I said. 500K MINIMUM. 5M better.
>
>
>
>
> Sent from my iPhone
>
> On Jun 4, 2011, at 3:03 PM, Jim Brown <[hidden email]> wrote:
>
>> On 6/4/2011 12:16 PM, Grant Youngman wrote:
>>> That would be a COMPLETE AND TOTAL waste of time. The K3 mic input Z is 600 ohms nominal per spec.
>>
>> Nominal is the operative word here. It's designed to have enough gain
>> for the low impedance mics commonly used with ham gear. If you study the
>> schematic, you see that the mic input stage of a K3 is NOT 600 ohms,
>> it's an opamp, which is a fairly high Z load. The input Z is at least
>> 10K, probably more like 15K -- there's a 10K resistor in series with the
>> input!
>>
>>>

Don Wilhelm-4

Re: Fwd: D 104

Grant,

Then why not just put a 1 megohm or so resistor in series with the mic
element. I believe the K3 mic input has adequate gain to compensate for
it, and it will keep the crystal (or ceramic) mic element happy.
The KISS principle applies - a resistor is much more simple than an FET
or a transformer.

73,
Don W3FPR

On 6/4/2011 4:12 PM, Grant Youngman wrote:

>
> Sent from my iPhone
>
> Begin forwarded message:
>
>> From: Grant Youngman<[hidden email]>
>> Date: June 4, 2011 3:12:03 PM CDT
>> To: "[hidden email]"<[hidden email]>
>> Subject: Re: [Elecraft] D 104
>>
>> 10-15k is not high enough for good performance from a D-104 element. It will sound like a squeaker at best, ir worse.
>>
>> Like I said. 500K MINIMUM. 5M better.
>

Jim Brown-10

Re: D104

In reply to this post by CHARLES WHITE

I'm re-sending this because it seems to have gotten lost.

> That would be a COMPLETE AND TOTAL waste of time. The K3 mic input Z
> is 600 ohms nominal per spec.

Nominal is the operative word here. It's designed to have enough gain
for the low impedance mics commonly used with ham gear. If you study the
schematic, you see that the mic input stage of a K3 is NOT 600 ohms,
it's an opamp, which is a fairly high Z load. The input Z is at least
10K, probably more like 15K -- there's a 10K resistor in series with the
input!

> The D-104 element needs 500k minimum and better no less than 5M. Last
> I heard the input stage of a K3 was not a 12AU7/12AX7.

This whole issue of impedance matching in audio is widely misunderstood.
In a passive mic (that is, one that is unamplified), it mainly affects
gain and sensitivity. The high-Z D104 is a very hot mic, and the K3 has
a LOT of available gain, so you can afford to lose a lot with the
mismatch. The second way that impedance CAN affect the sound of a
passive mic is frequency response (due to stray L and C in the capsule
or output network), but the K3 has VERY good and very flexible TXEQ,
which is very likely to be able to correct for any response deviations.

> That's why Z transformation (preamp, xformer) IS required for this
> element

The mic input stage of the K3 is quite well designed so that it can work
very with a wide range of mics. Calling it a 600 ohm input stage is
technically wrong and misleading (just as it misled you). Like I said, I
would try the mic first.

73, Jim Brown K9YC
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Grant Youngman

Re: Fwd: D 104

In reply to this post by Don Wilhelm-4

If there's enough gain, probably work fine. As large an R as possible. The termination Z affects the low freq response of the element. I realize some here aren't keen on that, but it makes a difference :-)

Sent from my iPhone

On Jun 4, 2011, at 3:37 PM, Don Wilhelm <[hidden email]> wrote:

> Grant,
>
> Then why not just put a 1 megohm or so resistor in series with the mic element. I
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AC7AC

Re: D 104

In reply to this post by Jim Brown-10

CONTENTS DELETED

The author has deleted this message.

Grant Youngman

Fwd: D 104

In reply to this post by CHARLES WHITE

Sent from my iPhone

Begin forwarded message:

> From: Grant Youngman <[hidden email]>
> Date: June 4, 2011 5:29:16 PM CDT
> To: Ron D'Eau Claire <[hidden email]>
> Subject: Re: [Elecraft] D 104
>

> Gain isn't the issue. It's the termination Z. A low Z termination will destroy the frequency response. Why do that and then attempt to fix it with TXEQ? Might as well just do something else from the start ....
>
> .
>>
>> Considering the K3's design to accommodate low-output mics, I'd be
>> astonished if an external preamp or impedance matching system was required.
>>
>> Ron AC7AC
>>
>>
>>

Hank Garretson

Re: Fwd: D 104

After reading all the comments about doing this and doing that, all I can
say is ...

I've made tens of thousands of SSB contacts using a fifty-year-old D-104
directly into the K3 with no resistors, no amplifiers, no transformers, no
nothing. Audio quality reports were always outstanding.

Don't let the naysayers discourage you. Try it. It will work just fine.

73,

Hank, W6SX

Mammoth Lakes, California

Elevation 8083 feet in John Muir's Range of Light
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AC7AC

Re: D 104

In reply to this post by AC7AC

CONTENTS DELETED

The author has deleted this message.

Grant Youngman

Re: D 104

I give :-/

Why use a D-104 if that's the only point? A $3 electret from " the shack" will do just as well.

Hopefully, someone will step in and kill this thread.

To the original poster - the simple solution is to use an Astatic stand with a preamp or something similar. Or as Don suggested, try a couple of meg in series with the element and see if the K3 gain is high enough to give you decent audio. If you have to EQ a D- 104, use some other mic.

Been using D-104's since 1957, and while I may not be a certified audio engineer, there is nothing wrong with "common knowledge". By the way, the ceramic version of this mike has lousy low freq response. You want the crystal element.

Grant/NQ5T

Sent from my iPhone

On Jun 4, 2011, at 5:55 PM, "Ron D'Eau Claire" <[hidden email]> wrote:

> Changing the termination only modifies the frequency response in the input
> circuit. What does it matter whether the frequency response is established
> at the microphone input or later in the audio system?
>
> Ron AC7AC
>
> -----
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Don Wilhelm-4

Re: D 104

Despite all the "solutions" presented, the D-104 Lollipop is one of
those classic mic frames that just will not give up. I have 2, one with
no PTT lever on it (anyone have one for sale?) and another with a Heil
HC-5 cartridge instead of the original mic element.

For those who have a D-104 frame and an element that does not work, YES,
go down to "the shack" and pick up one of those $3 electret mic
elements. Remove the original element and put the electret in its place
(with a lot of foam to take up the excess space). Turn on mic bias in
the K3 and you will have the classic D-104 mic look with good
performance (just as though it were an Elecraft MD2).

Be creative, and you too can have a working classic microphone.

BTW - I use an Elecraft MD2 mic (no longer available) and like it a lot.

73,
Don W3FPR

On 6/4/2011 7:25 PM, Grant Youngman wrote:

> I give :-/
>
> Why use a D-104 if that's the only point? A $3 electret from " the shack" will do just as well.
>
> Hopefully, someone will step in and kill this thread.
>
> To the original poster - the simple solution is to use an Astatic stand with a preamp or something similar. Or as Don suggested, try a couple of meg in series with the element and see if the K3 gain is high enough to give you decent audio. If you have to EQ a D- 104, use some other mic.
>
> Been using D-104's since 1957, and while I may not be a certified audio engineer, there is nothing wrong with "common knowledge". By the way, the ceramic version of this mike has lousy low freq response. You want the crystal element.
>

Don Wilhelm-4

Re: D 104

In reply to this post by Jim Brown-10

Jim and all,

Looking at the schematic for the K3 mic input, it is an op amp with a
gain of 10. It looks to be a classic differential amplifier with a 10k
resistor in both the + and the - inputs. That would produce an input
impedance of about 20k ohms. Matching is not necessary (nor desirable).

So yes, it is not a "600 ohm input impedance" - it is the nominal
impedance for a typical driving device which will produce sufficient
voltage swing for maximum input - that is a LOT different than "matching
impedance".

In audio applications, this is quite common - the driving impedance is
not matched to the input impedance of the receiver. Instead, the
"impedance" of the driving device will dictate the voltage and current
required for operation. The op amp only cares about the voltage
reaching the input of the IC. The driving voltage will meet the input
impedance of the op amp and current will flow. As long as the driving
voltage is within the range of voltages expected by the transceiver
designer, then the impedance of the driving device does not matter either.

In other words, the K3 mic "input impedance" is a derived value, and has
nothing to do with reality - it all has to do with the voltage and
current characteristics of the driving device (in this case, the
microphone).

In other (2nd other) words, do not calculate based on the nominal "input
impedance" of the receiving op amp, it can be very different than stated
- the voltage swing is what really matters.

Jim is correct - it is quite common to have high input impedance devices
in the audio world - maximum power transfer is NOT the goal, but an
appropriate voltage swing is required to drive the device, and that is
often dictated by the capability of the driving device, and not by the
input device. Impedance matching is not required. That has been the
case since op amps came into common use in the audio field - no
impedance matching, just provide enough voltage swing to operate the op
amp as the designer has required. Low impedance driving devices may not
provide enough voltage swing - so the "600 ohm" specification can be
construed as stating "a typical 600 ohm driver of the type expected
(typical microphone output) will provide sufficient voltage swing for
proper operation" -- it says nothing about the actual input impedance of
the receiver.

This is quite different than transmitter PA stage output circuits which
require matching to (typically) a 50 ohm impedance for maximum power
transfer.

73,
Don W3FPR

On 6/4/2011 4:03 PM, Jim Brown wrote:

> On 6/4/2011 12:16 PM, Grant Youngman wrote:
>> That would be a COMPLETE AND TOTAL waste of time. The K3 mic input Z is 600 ohms nominal per spec.
> Nominal is the operative word here. It's designed to have enough gain
> for the low impedance mics commonly used with ham gear. If you study the
> schematic, you see that the mic input stage of a K3 is NOT 600 ohms,
> it's an opamp, which is a fairly high Z load. The input Z is at least
> 10K, probably more like 15K -- there's a 10K resistor in series with the
> input!
>
>> The D-104 element needs 500k minimum and better no less than 5M. Last I heard the input stage of a K3 was not a 12AU7/12AX7.
> This whole issue of impedance matching in audio is widely misunderstood.
> In a passive mic (that is, one that is unamplified), it mainly affects
> gain and sensitivity. The high-Z D104 is a very hot mic, and the K3 has
> a LOT of available gain, so you can afford to lose a lot with the
> mismatch. The second way that impedance CAN affect the sound of a
> passive mic is frequency response (due to stray L and C in the capsule
> or output network), but the K3 has VERY good and very flexible TXEQ,
> which is very likely to be able to correct for any response deviations.
>

P.B. Christensen

Re: Fwd: D 104

In reply to this post by Don Wilhelm-4

> Then why not just put a 1 megohm or so resistor in series with the mic
> element. I believe the K3 mic input has adequate gain to compensate for
> it, and it will keep the crystal (or ceramic) mic element happy.
> The KISS principle applies - a resistor is much more simple than an FET
> or a transformer.

Plenty of folks have been doing that for decades with their D-104 mics.
It's fine unless you want to optimize SNR as the source Z of the generator
(D-104) increases by the amount of the added resistance . I've tried it
both ways, and a JFET configured either as a source-follower or
common-source amp with a J201 JFET has always been noticeably quieter when
compared to the addition of a single resistor after mic element.

For the K3, it's easy to optimize the D-104 with a JFET by using exactly two
parts: a pair of resistors. That's just two more parts than one 1 meg-ohm
resistor. In the K3 menu, one simply activates mic bias. When using a
JFET as a common-source amplifier, the drain resistor is supplied by the K3
(R89 = 5.6K). A 1uF cap also internal to the K3 (C28) isolates audio from
the DC bias injection. That leaves only a source resistor and gate leak
resistor. Sure, not quite as economical as a single 1 meg resistor after
the mic element, but with only three total parts, I find that the added
performance more than offsets the addition of a two more parts. In one of
my D-104 mics, the JFET and two resistors are mounted with adhesive tape
right on the back of the D-104 element. It doesn't get much simpler.

The JFET is functioning only as an impedance transformation device -- it is
not matching impedance, nor does it need to for the reasons cited by you and
K9YC.

Paul, W9AC

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