[Elecraft] D104 mic

[Chris Hembree]

Anyone ever use a D-104 (non amp) on a K3. How does it sound?
Chris W7CTH

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[Don Wilhelm]

Chris,

Unmodified, it will probably sound terrible (very 'bright with lots of
highs, weak lows), but with a bit of work, it will sound great - just
like Astatic intended.
The D-104 element is either crystal or ceramic, and wants to work into a
high impedance (like the grid of a vacuum tube with a 1 megohm 'grid
leak' resistor) load. Modern transceivers present a much lower
impedance load (nominally 600 ohms).

I have seen some comments that the simple insertion of a 1 megohm
resistor in series with the AF line is all that is needed. That may be
the first thing to try. I strongly suggest you use the K3 monitor
function with the K3 in TEST mode and record your audio on the computer
- listen to the recording to see what it sounds like (that is almost
impossible to judge while listening

With a single FET buffer or an op amp between the D-104 and the K3 (or
any other transceiver), the D-104 will "come to life" just as it did
with the old vacuum tube rigs.

An op amp solution is a natural because the characteristic of an op amp
is very high input impedance and low output impedance - perfect for the
D-104. An LM358 wired as a unity gain buffer should do the job nicely,
and for the voltage swings involved (small) the LM358 can be powered
from the +8 volts available at the front microphone jack pin 6. If you
would want to use the rear microphone jack, the FET solution would be
better because the voltage to drive the FET can be supplied by turning
bias on.

I am not going to give you a circuit diagram because I have not
developed and tried it out.
There is another solution - that is to replace the original element with
an electret element, or with a Heil HC-4 or HC-5 element (Heil offers a
kit for that).

73,
Don W3FPR

[WA6L]

Hi, Chris,

Heil makes a conversion kit for the D-104. I am using it and have had great
results. If you would like more information, please see my eHam review at
http://www.eham.net/reviews/review/65769

73,

John, WA6L

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[Tom W8JI]

It will sound great if you add a J310 or similar JFET source follower. Very
flat clean response.

A source follower is very simple. Use a low voltage .01 uF or .05 uF disc
cap to the gate. Use a 100k to 1 meg ohm resistor from gate to ground. Put a
560 ohm source resistor to ground, and couple the source to the K3 through a
.47 uF cap. The drain is bypassed and decoupled to a 9 volt battery or clean
12 volt supply. If you have a lot of RF you might need to decouple the audio
output line.

The size of the gate resistor will control loading on the D104 and the
frequency response. The higher the resistance the more the low frequency
response.

Until I started using a Sennheiser computer headset I used a D104 head on
all my rigs.

73 Tom

[Hank Garretson]

On Fri, Jul 9, 2010 at 5:00 PM, Don Wilhelm <w3...@embarqmail.com> wrote:

Unmodified, it will probably sound terrible (very 'bright with lots of
> highs, weak lows), but with a bit of work, it will sound great - just
> like Astatic intended.
>

My experience is different.

When I first got my K3, I used an unmodified crystal-element D-104 I've had
since 1956. No amps, no anything. I didn't do anything special with the K3
except adjust gain and ALC controls per the K3 manual. On the air checks
with guru K9YC and on the 3830 net after an NCCC Sprint resulted in superb
voice-quality reports.

So, plug it in and give it a try (with on-the-air checks from people you
trust).

73,

Hank, W6SX

Mammoth Lakes, California

Elevation 8083 feet in John Muir's Range of Light

[Paul Christensen]

> Use a 100k to 1 meg ohm resistor from gate to ground. Put a
> 560 ohm source resistor to ground, and couple the source to the K3 through
> a
> .47 uF cap.

I agree with comments from Tom and Don. However, the "leak" resistor from
the FET's gate to ground usually isn't necessary as the crystal cartridge
itself often provides ample leak to bias the FET.

The source resistor can be calculated to set mid-point bias a bit more
precisely by taking the reciprocal of the FET's transconductance (gm or gfs)
value. For example, the Fairchild MPF-102 is specified with a gm value
between 2000 uS and 5000 uS. The geometric mean of those values is about
3,000 uS. The reciprocal value is 333. So, a 330-ohm source resistor to
ground is a good choice when the actual gm value is unknown.

I would stay away from op-amp solutions for a number of reasons: First,
unless a bi-polar supply is used, a voltage divider must normally be set up
to bias the op-amp's non-inverting input, and consequently, the op-amp
output to half the supply voltage. However, some op-amps are designed to
operate from single supplies, contain internal dividers, and require no
external divider components. Second, the parts count can get to be quite a
bit more than a single FET. Finally, unless a JFET-input op-amp or biFET
op-amp is used (e.g., Texas Instruments TL071), obtaining stable operation
and achieving a high input Z into the megohm range is pretty difficult. The
biFET designs can more easily achieve this.

As Don pointed out, some folks use a 1 to 5 meg resistor between the D-104
cartridge and the low-Z input of a transceiver. That re-establishes balance
in frequency response from the cartridge but it also sets up a very
asymmetric voltage divider, the equivalent of which is a pot with its wiper
arm nearly at ground potential. Often, the result is low level and poor
audio SNR.

All things considered (RF immunity, single supply, low parts count, low
current, super high input Z, and very low output Z), it's pretty hard to
beat a single FET when used as a source follower with crystal mics.

Although I do own a condenser mic, my primary mic is ca. 1935 Shure 70H
crystal type with a JFET interface. With that combination, response is
reasonably flat to about 80 Hz.

Paul, W9AC

[Jim Brown]

On Fri, 9 Jul 2010 20:47:36 -0400, Tom W8JI wrote:

>It will sound great if you add a J310 or similar JFET source follower.

Hams spend WAY too much time hand-wringing about impedance matching in
audio circuits. Audio circuits have not been impedance matched for
nearly 50 years! As long as the input Z of the preamp is not so low
that it loads the mic severely, everything should be fine. The input Z
of the K3 mic circuit is on the order of 10K. That's pretty high, and
most mics ought to be quite happy with it.

For a passive mic, the downside of excessive loading is usually some
modification of the frequency response, some loss of level, but no
distortion. TXEQ can easily fix any response problems, and the K3 has
plenty of mic gain to make up for any loss.

Tom's advice is solid if it's a VERY high Z mic, BUT it may also depend
on the version of D104 that you have. I haven't played with a D104 for
nearly 40 years, so don't know enough about that to have an opinion
that matters. :) I would first try it straight into the K3 as Hank did,
adjust levels per Elecraft intructions, then get someone with good
audio ears to talk you into TXEQ settings on the air. If you can't make
it sound right, then follow Tom's advice and build the follower
circuit.

73, Jim K9YC

[Tom W8JI]

I like a microphone that has proper level and response so I don't need to
run gain up near full open and works with any rig without cranking the lows
up ten or 15 dB, thus the reason the reason my D104 has a source follower
that makes the mic output Z lower than the radio input Z so it appears as a
voltage source.

:-)

[Bob Stevens]

I'm using one too. It Works great, good reports and is easy to install.
Plus, the D104 is a beautiful mike.

Hi, Chris,

Heil makes a conversion kit for the D-104. I am using it and have had great
results. If you would like more information, please see my eHam review at
http://www.eham.net/reviews/review/65769

73,

John, WA6L

--

______________________________________________________________

[Eric Fitzgerald]

This will probably end up qualifying for the lamest question ever asked but I would really like to get on the air for IARU.

I just set up my K3 in a new location after Field Day and I've been working the digital modes no problem. I switched over to USB on 20m this morning and plugged in my Heil ProSet and... no audio into the K3. I checked the obvious - mic gain, monitor gain, connections, etc but no joy - I cannot budge the ACL meter and nothing heard in my monitor. PTT is working just no audio into the radio. I even tried a different mic into the front panel jack (Obviously switching to the front panel input) and same result, no audio.

I double checked that the Line In is still delivering audio and it is. Just nothing via the mic inputs.

Any ideas about what stupid thing I'm doing?

TIA

73 de Eric, KG6MZS

[Don Cunningham]

Eric,
Does the Heil ProSet need bias on to work?? I don't have one, but remember
someone else having that problem, I think.
73,
Don, WB5HAK

[Eric Swartz WA6HHQ - Elecraft]

Only the one with the iC element, which we sell as the Proset-K2 (for
the K2 and K3).

The Heil HC4, HC5 and Goldline dynamic elements do not need bias turned on.

73, Eric

_..._

[Eric Fitzgerald]

Hi Don,

Thanks for the reply. It was working fine on whatever setting the bias was on before Field Day. Also the same thing happens with a Kenwood MC-60 plugged into the front panel jack after switching to that input. Only my computer's sound card seems to move the ALC meter via the Line In input.

I have memory settings for digital and SSB on each band so the inputs, mode and the like get switched with the memory.

73 de Eric, KG6MZS

[Bob Stevens]

I forgot to add that the element in the mic conversion is the HC5

-----Original Message-----
From: elecraft...@mailman.qth.net
[mailto:elecraft...@mailman.qth.net] On Behalf Of Bob Stevens
Sent: Saturday, July 10, 2010 11:49 AM
To: 'WA6L'; elec...@mailman.qth.net
Subject: Re: [Elecraft] D104 mic

[WA6L]

Hi, Eric,

I think you posted this to me instead of to the Elecraft reflector. I am
just about the worst person you could ask about this, as I work 99.9% CW and
digital modes and almost never connect a mic. You might want to repost it
to the reflector.

Good luck and 73,

John, WA6L

On Sat, Jul 10, 2010 at 9:56 AM, Eric Fitzgerald-2 [via Elecraft] <
ml-node+5278166...@n2.nabble.com<ml-node%2B5278166-66...@n2.nabble.com>
> wrote:

> This will probably end up qualifying for the lamest question ever asked but
> I would really like to get on the air for IARU.
>
> I just set up my K3 in a new location after Field Day and I've been working
> the digital modes no problem. I switched over to USB on 20m this morning
> and plugged in my Heil ProSet and... no audio into the K3. I checked the
> obvious - mic gain, monitor gain, connections, etc but no joy - I cannot
> budge the ACL meter and nothing heard in my monitor. PTT is working just no
> audio into the radio. I even tried a different mic into the front panel
> jack (Obviously switching to the front panel input) and same result, no
> audio.
>
> I double checked that the Line In is still delivering audio and it is.
> Just nothing via the mic inputs.
>
> Any ideas about what stupid thing I'm doing?
>
> TIA
>
> 73 de Eric, KG6MZS
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[Eric Fitzgerald]

Hi Mike;

Thanks for the reply. My memory presets switch the MIC SEL to rear panel, so MIC+LIN setting doesn't matter as you noted. Just for grins I just tried it both ways with no joy. I'm sure this is a really stupid thing I am doing but I just can't figure it out.

What is maddening is that I had this all set up and working fine before Field Day.

73 de Eric, KG6MZS

On Jul 10, 2010, at 12:05 PM, Mike Kravitz wrote:

> Hi Eric,
>
> If you leave CONFIG:MIC SEL showing LINE mode you also must have MIC+LIN turned on. (It's a MENU item, not a CONFIG item). If you don't need line-in, just turn the CONFIG:MIC SEL to either FP or RP.
>
> 73,
> Mike K2MK

[Grant Youngman]

I know a lot of people do this. But once done, it's no longer a D-104 -- it's just one more HC-5 in a fancy housing. This is one case where it may look like a duck, but doesn't necessarily sound like a duck. I recognize some may consider that a plus :-)

I understand it, but it is a shame that Astatic can no longer economically manufacture the original cartridge for something this venerable, if not downright iconic ...

Grant/NQ5T

On Jul 10, 2010, at 10:41 AM, Bob Stevens wrote:

> I forgot to add that the element in the mic conversion is the HC5
>
>
>

> Heil makes a conversion kit for the D-104. I am using it and have had great
> results.

[Phil Kane]

On 7/10/2010 7:37 PM, Grant Youngman wrote:

> I understand it, but it is a shame that Astatic can no longer
> economically manufacture the original cartridge for something
> this venerable, if not downright iconic ...

Definitely iconic - the D-104 was the overwhelmingly first
choice of the out-of-band-and-overpower CBers for use with
their modified Yaesu FT-101E transceivers in the 1970s. Some
of those folks eventually "saw the light", got their ham
licenses, abandoned CB, and became good hams.

'Nuf said... ;-)

-- 73 de K2ASP - Phil Kane
Elecraft K2/100 s/n 5402
(lic. before there was a CB)

[Tom W8JI]

> Definitely iconic - the D-104 was the overwhelmingly first
> choice of the out-of-band-and-overpower CBers for use with
> their modified Yaesu FT-101E transceivers in the 1970s. Some
> of those folks eventually "saw the light", got their ham
> licenses, abandoned CB, and became good hams.

My first exposure to the D104 was in 1962 when I rode my bicycle over to see
Bob, W8YAT, who had an outstanding 160 meter AM signal with his Viking
Valiant transmitter. My neighbor Fred, W8IQC, used one on his Ranger I
transmitter, so they were very popular even in the early 60's and for
non-CB'ers. My oldest D104 has been with me since the 70's when I used it
with a Drake line. Still ticking just fine and still excellent audio after
all these years, and with the little cheap FET mod works great with either
low or very high impedance loads 40 years later!

73 Tom

[Bob W7AVK]

Tom and Gang - The D104 is a lot older. It was the first product of
the Astatic Corporation founded in 1934 and made in Youngstown, Ohio.
See http://en.wikipedia.org/wiki/Astatic_Corporation

73 Bob W7AVK
K3/100 kit s/n 4365

[Grant Youngman]

I purchased my first one in 1959 with the adapter for a standard mic stand -- couldn't afford the PTT stand in those days, and a DX-40 didn't have PTT anyway. Ultimately I had (and still have) several sitting on the shelf, including the boxed version Astatic sold just before the end of production -- never opened, waiting for a rainy day. The crystal elements will last a long time, too, if you don't leave them sitting out in the sun for the summer, don't store them in a sauna, and don't purchase the one you just saw fall off the tailgate of the pick-up truck onto the pavement :-)

The last radio I regularly used a D-104 (and sometimes 10DA) with was an IC-781. Maybe it's time to wire one of them up for the K3 :-)

Grant/NQ5T

On Jul 11, 2010, at 3:53 PM, Bob W7AVK wrote:

> Tom and Gang - The D104 is a lot older. It was the first product of
> the Astatic Corporation founded in 1934 and made in Youngstown, Ohio.

______________________________________________________________

[Bob Nielsen]

I have had my D104 since 1953 (used with a Viking II). It fell off
the desk one day and I cringed and and looked inside to see that the
crystal element had become detached. Isent it to Astatic asking them
to give me an estimate for repair. The repaired mike came back by
return mail, no charge. I haven't used it for many years, but
someday....

Bob, N7XY

[Bob Stevens]

The cartridge in mine went bad; too much West Texas heat I guess. But it
still looks good :-)

-----Original Message-----
From: elecraft...@mailman.qth.net
[mailto:elecraft...@mailman.qth.net] On Behalf Of Grant Youngman
Sent: Saturday, July 10, 2010 9:38 PM
To: Elecraft Reflector
Subject: Re: [Elecraft] D104 mic

[Don Wilhelm]

Bob,

Put a Heil HC-5 in it (Heil provides a kit) or put an electret element
in the D-104 head. It will work great again.

73,
Don W3FPR

Bob Stevens wrote:
> The cartridge in mine went bad; too much West Texas heat I guess. But it
> still looks good :-)
>
>

[Paul Christensen]

> The cartridge in mine went bad; too much West Texas heat I guess. But it
> still looks good :-)

Mouser carries close replacements of the original Astatic crystal cartridge.
Less than $5 each, plenty in stock. I've used them as replacement
cartridges in my ca. 1936 D104 and Shure 70H.

http://tinyurl.com/2vjlqeh

Paul, W9AC

[David Pratt]

Replacement crystal elements are available for $12 on ebay.com, Grant &
Bob. They are not the genuine article but they are a similar size and
the speech quality is indistinguishable from the original Astatic
version; I use one.

73 de David G4DMP

In a recent message, Bob Stevens <bob...@suddenlink.net> wrote ...

>
>The cartridge in mine went bad; too much West Texas heat I guess. But it
>still looks good :-)
--

David G4DMP
Leeds, England, UK
------

[Richard S. Lindzen]

Does anyone have experience with the amplified D104?

Dick, KA1SA, #911

[Tom W8JI]

> Does anyone have experience with the amplified D104?
>
> Dick, KA1SA, #911

I cut those boards out of mine, except for the PTT switch mounting. I prefer
something more simple and easily controlled.

[Bill NY9H]

I'd think that way to go would be to put a $ .50 electret capsule or
one swapped from an old telephone set ( you know the junkers) that
used an electret ,.,,,
set the bias on, tweak up the EQ IF preferred,,,and have a great
sounding d-104...

I put one in front of a dynamic cartridge in one of my old AKGs, not
acoustically correct but worked great for ssb... and had dual outputs
... one dynamic and one hot electret....
bill/3

[Jim Brown]

On Mon, 12 Jul 2010 10:22:06 -0400, Bill NY9H wrote:

>I'd think that way to go would be to put a $ .50 electret capsule or

It worked for Bob Heil!

73, Jim K9YC

[Mark - W5EZY]

Does anyone have experience with the amplified D104?

Dick, KA1SA, #911

Dick,

If you have a D104 with the original crystal element, you can build the
below amplifier to interface with your K2/3. I did, and it worked great;
had really good "punch" for dxing. I wired it to get power from the K2 for
the amplifier circuit. Check out: http://members.cox.net/n4jk/d104.htm

Mark - W5EZY

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[Richard S. Lindzen]

Thanks. This is what I was looking for. The D104 is a classy looking mic.

Dick

[Chris W7CTH]

This link from W5EZY should make all the old D-104's come back to life.

Chris W7CTH
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