There is an interesting article in Electric Radio Magazine for September 2001 addressing the effect of load impedance on the "bare" D-104 element.
"With a crystal microphone, the bass response is governed by the value of the grid resistor in the first stage. And input resistor of 100k ohms will limit or "rolloff" at about 500 cycles, 500k at about 250 cycles, and a 1 megohm will extend the response to about 100 ycles." - W F Soules, W8HCW, Electro-Voice, Inc., 1958. This variation in response can make a big, little, or no difference, depending upon your individual voice characteristics. I assume the reference to the 470 ohm resistor below is actually to a 470k resistor? The base mounted preamp was in fact a product of the CB market, but was intended to extend the life of the D-104 into the solid state era of low impedance microphones rather than to enable overdriving the audio! The amp also eliminated the effect of load impedance on the mic, and allowed it to be used with both high and low impedance circuits. 73, Garey - K4OAH Atlanta ----- Original Message ----- From: "Tim Kass" <[EMAIL PROTECTED]> > > I also agree with the group, dont need a transformer, been using one for a > long time, great audio...also..better off w/o the preamp...stick a 470 ohm > 1/2 watt resister in the hot lead in series with the mic, improves audio > response...got this from Jack Geihl WB8BFS ...73 Tim K8WBL > > >From: "William J. Bennett" <[EMAIL PROTECTED]> > >Reply-To: "William J. Bennett" <[EMAIL PROTECTED]> > >To: "Drake List Server" <[EMAIL PROTECTED]> > >Subject: [Drakelist] Drake T4X Microphone Question > >Date: Thu, 3 Apr 2003 07:54:55 -0500 > > > > > >I would like to use a D104 with my T4XC. I purchased a HI impedance xformer > >from Hiel but I'm not sure of the pin out of the D104 (red, white, shield) > >and how to wire the transformer between the T4X and the D-104. Does anyone > >have any experience using a D-104 with a Drake transmitter? > > > >TIA > > > >Bill K3TNM ---------------------------------------------------------------------- Submissions: [EMAIL PROTECTED] Subscribe: [EMAIL PROTECTED] - subscribe drakelist in body Unsubscribe: [EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost: [EMAIL PROTECTED] - help in body of message Brought to you courtesy of TLCHost.net http://www.tlchost.net ----------------------------------------------------------------------
