More D-104 Questions

[WA2SQQ]

I was reading AB2EZ's post about D-104's.
http://amfone.net/Amforum/index.php?topic=8975.0

I have two, one that I guestimate is from the early 1960's and the amplified "Silver Eagle" version. Th eolder version was used on my old Swan 500CX and various other tube radios, so I have to believe it was one of the "high impedance" crystal elements. I'm not sure about the newer versions, or even if it uses the same type of element. Does anyone know of any historical data on the D104 - perhaps some time line on when and what changes have occurred? I'm looking for a circuit to use so I can dry my older version on my new Flex 6500. Suggestions? Also does anyone know who makes some of the gray hammertone paint the D-104 base used? Someone sprayed mine candy apple blue!

[Pete, WA2CWA]

Here's some history: http://www.k3dav.com/astaticd104microphone.htm
Google can probably bring up more.

I've used my un-amplified D-104 with my Flex 5000A. Connected it to the audio input jack on the rear. It worked like a crystal mike should but I wouldn't consider D-104's to be hi-fi sounding audio. Even my $1.95 Lafayette lapel mike worked.

[W3GMS]

I was reading AB2EZ's post about D-104's.
http://amfone.net/Amforum/index.php?topic=8975.0

I have two, one that I guestimate is from the early 1960's and the amplified "Silver Eagle" version. Th eolder version was used on my old Swan 500CX and various other tube radios, so I have to believe it was one of the "high impedance" crystal elements. I'm not sure about the newer versions, or even if it uses the same type of element. Does anyone know of any historical data on the D104 - perhaps some time line on when and what changes have occurred? I'm looking for a circuit to use so I can dry my older version on my new Flex 6500. Suggestions? Also does anyone know who makes some of the gray hammertone paint the D-104 base used? Someone sprayed mine candy apple blue!

I am assuming that your Flex does not have an extremely high input input impedance.    The low frequency response goes away when a xtal element is driving a lower input impedance.  When the xtal element is loaded with 4.7M or so, the low end response is very good.  A simple FET source follower will do a great job in interfacing your very high impedance microphone to a rig with a lower input impedance.  The output voltage of a D-104 xtal element is quite high when loaded properly, so there is no need to further amplify it.  I personally do not like the design of the amplified versions and remove them and put in the source follower circuit.   

Joe - W3GMS   

[W2VW]

I was reading AB2EZ's post about D-104's.
http://amfone.net/Amforum/index.php?topic=8975.0

I have two, one that I guestimate is from the early 1960's and the amplified "Silver Eagle" version. Th eolder version was used on my old Swan 500CX and various other tube radios, so I have to believe it was one of the "high impedance" crystal elements. I'm not sure about the newer versions, or even if it uses the same type of element. Does anyone know of any historical data on the D104 - perhaps some time line on when and what changes have occurred? I'm looking for a circuit to use so I can dry my older version on my new Flex 6500. Suggestions? Also does anyone know who makes some of the gray hammertone paint the D-104 base used? Someone sprayed mine candy apple blue!

I am assuming that your Flex does not have an extremely high input input impedance.    The low frequency response goes away when a xtal element is driving a lower input impedance.  When the xtal element is loaded with 4.7M or so, the low end response is very good.  A simple FET source follower will do a great job in interfacing your very high impedance microphone to a rig with a lower input impedance.  The output voltage of a D-104 xtal element is quite high when loaded properly, so there is no need to further amplify it.  I personally do not like the design of the amplified versions and remove them and put in the source follower circuit.   

Joe - W3GMS   

You are 100% correct Joe however you are fighting a losing battle.

There is far more incorrect information about D-104s on radio sites than correct info.

New guys read it in several places and take it as truth.

#1 botched subject in radio land.

73,
Dave

[N2DTS]

I have had the same un amplified D104 for the last 35 years.
Got it new direct from Astatic and its been fine ever since.
Its nice to be able to 'tune' the sound with the grid input resistance, lower is restricted audio, higher is more low end.
Someplace between 2 and 4 meg is the sweet spot for me.
1 meg (used in most stock rigs) is contest audio.
Lower is even worse.

[WD8BIL]

On the Viking Bud the grid resistor is a 5 Meg pot with a 1 Meg resistor in series with it. I call it the tone control!

[N2DTS]

That is a great idea, how come I did not think of it?
(as long as you can keep the hum out)

On the Viking Bud the grid resistor is a 5 Meg pot with a 1 Meg resistor in series with it. I call it the tone control!

[WD8BIL]

Haven't had a problem with that Brett.

I do find a need to adjust it for each D104 I have. Each element is a bit different.

[WBear2GCR]

I think that the answer to one of the questions is that all the elements are made from the same Rochelle Salt crystal, except for those that use a "ceramic" element. There are not very many with the ceramic element, maybe none in the D-104 package. Not certain if there are any ceramic elements in the D-104, but you can assume a crystal element. Which all vary somewhat in sound and response.

You can take the head off the amplified one and use it on the other stand, etc.  They are all interchangeable.
They all sound a bit different. Pick the one you like.

The Jfet preamp is a best bet.

                              _-_-

[Steve - K4HX]

Yes, the load-Z has a big effect on the low frequency response.




Here's a slightly more sophisticated circuit for both bass and treble tone controls with a D-104.

[WB2CAU]

There are not very many with the ceramic element, maybe none in the D-104 package. Not certain if there are any ceramic elements in the D-104, but you can assume a crystal element. Which all vary somewhat in sound and response.

            

The D-104C had a ceramic instead of a crystal element.

[W2VW]

There are not very many with the ceramic element, maybe none in the D-104 package. Not certain if there are any ceramic elements in the D-104, but you can assume a crystal element. Which all vary somewhat in sound and response.

            

The D-104C had a ceramic instead of a crystal element.

And the enclosure was the same form factor as for the crystal element. Not many of those to be found.

[DMOD]

I was reading AB2EZ's post about D-104's.
http://amfone.net/Amforum/index.php?topic=8975.0

I have two, one that I guestimate is from the early 1960's and the amplified "Silver Eagle" version. Th eolder version was used on my old Swan 500CX and various other tube radios, so I have to believe it was one of the "high impedance" crystal elements. I'm not sure about the newer versions, or even if it uses the same type of element. Does anyone know of any historical data on the D104 - perhaps some time line on when and what changes have occurred? I'm looking for a circuit to use so I can dry my older version on my new Flex 6500. Suggestions? Also does anyone know who makes some of the gray hammertone paint the D-104 base used? Someone sprayed mine candy apple blue!

STU's testing and analysis of the D-104 should be made a "sticky."

Phil - AC0OB