Comments about using D-104 elements and 10DA elements on G stands. Yes, the
amp in the base if best viewed as an active circuit to work as an impedance
transformer. These mike elements are most happy seeing a load of 3.3
megohms or higher. The amp in the base of the GA stand provides that
condition. Don't consider the circuit in the base as such although it will
provide a good bit of voltage gain.
Newer solid state radios, and I'm speaking of those made from the 70's on,
typically state that the mike input impedance is High. Well, high as
compared to what? These radios and their solid state input provides
something in the order of 50K to 100K ohms input impedance for the mike. In
general terms one would consider 100K ohm today as high impedance, but to
these mikes, this is nowhere near what they expect or were designed for.
Alas, enter the good old amplified Astatic G stand.
And again, using a G stand with the active circuit in the base, one will
find it quite capable of overdriving the input or 1st audio stage of today's
solid state radios. Once the input stage is overdriven, distortion exists
and no amount of reducing the mike gain in the radio will resolve the
problem. This is due largely to the fact that the mike gain is after the
1st stage.
A second point specifically with the D-104 crystal element is the fact they
are fragile. Fragile in the way that heat and moisture will cause it to
become brittle and eventually fail. This is one reason that the D-104C was
introduced. The C is for ceramic element which is less prone to heat and
moisture effects. I've heard mike after mike that sounded bad. That's the
first sign of a bad element. Bad not as in no output but simply bad
sounding output. A good crystal element in a "lollypop D-104" with a 3.3
meg load on the output sounds great on SSB or AM. Feed one of these into a
100 K or less ohm input and they rapidly begin to sound bad, thus muddy, and
lacking in a good clean crisp sound. From there the bad reputation exists
when indeed the condition of the mike and the application is the part that
is truly at fault.
Regarding the Argo, the "banana" mike sold with/for the radio worked well as
do some other "high impedance" mikes such as the Shure 444. Keep in mind
here that the use of "high impedance" is likely something in the 10K to
100K ohm range.
73
Bob, K4TAX
----- Original Message -----
From: "Geoffrey S Mendelson" <gsm@mendelson.com>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Cc: <nf7v@cox.net>
Sent: Tuesday, November 27, 2007 9:20 AM
Subject: Re: [TenTec] Argo 509 mic
> On Tue, Nov 27, 2007 at 02:52:58PM +0000, jones_winston@bellsouth.net
> wrote:
>
>> I've used several mics with my 509, including the Ten-Tec banana style
>> mic that was sold with it. I get the best results with a Shure 444 high
>> impedence. It gives more punch than the Ten-Tec mic. A D-104 works fine
>> also, but if it's the amplified model, you have to be careful not to
>> overdrive it.
>
> Reading this over I noticed a second part of the question, I also want
> to make a comment about the D-104 (and 10DA). The amplifier in these
> mikes is not to make them "hotter" or "better", it's to match a high
> impedance microphone to a low impedance radio. It won't have any
> effect on the audio, except as you say to overdrive the radio
> if the gain is set too high.
>
> As to the second original question:
>
>> > I have just aquired an Argonaut 509 and I need a mic for it.
>> > What recomendations do some of you have, and is something with an
>> > equalizer
>> > going to get through a bit better then a standard mic?
>
> Maybe. A speech processor, or the SSB "improvment" mod that is floating
> around might help. A microphone that works better for your voice,
> for example a 10-DA over a D-104 for mine, or a D-104 over a 10-DA
> for my wife, would also help.
>
> With that said, while the Argo's have been around a long time and
> lots of people have published mods for them, they are fine performers
> as they are. There were many rigs of the time that needed help
> (the HW-8 comes to mind), the Argo is not one of them.
>
> Geoff.
>
> --
> Geoffrey S. Mendelson, Jerusalem, Israel gsm@mendelson.com N3OWJ/4X1GM
> IL Voice: (07)-7424-1667 U.S. Voice: 1-215-821-1838
> Visit my 'blog at http://geoffstechno.livejournal.com/
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