Technical Info needed

[kd8dey]

Anybody know what the peak output voltage is for an unamplified astatic DN-500 .

Anybody got one with access to an O-scope?

Don't care if you speak, whistle, shoot, or lob nasty farts in it's direction as long as I get the numbers :-D

[WØTKX]

About 2-3 volts P-P. It depends on the "load" the testing puts on the circuit. I'm guessing your using maybe a 1 meg probe?

The old VTVM meters with 50K Ohms/Volt would show about half that. AFAIK the old "salt crystal" elements were a little hotter.

[kd8dey]

Don't have that kind of equipment here at home. I have the amplifier for the d-104 duplicated in multisim BUT I do not know what kind of signal voltage is being fed from the microphone element/transformer INTO the amplifier .
not up to it this late but I got the formula somewhere to figure the input impedence.....

[NQ6U]

Can't find info on a DN-500 but according to this site (http://www.jt30.com/jt30page/oldsite/micids/astid.html), a DN-50 has a 38 ohm impedence

[kd8dey]

Can't find info on a DN-500 but according to this site (http://www.jt30.com/jt30page/oldsite/micids/astid.html), a DN-50 has a 38 ohm impedence

Is that at the output transformer ? :)

[NQ6U]

Is that at the output transformer ? :)

I have no idea. If you followed the link I provided, you know as much as I do!

[kd8dey]

It was late. I must have been asleep at the switch. didnt realize the link was there lol.

[NQ6U]

It was late. I must have been asleep at the switch. didnt realize the link was there lol.

I shouldn't have tried to be clever and just done it like this:

http://www.jt30.com/jt30page/oldsite/micids/astid.html

[kd8dey]

I got a chance to hook it up to a O-scope today. Didn't get much of a reading out of it lobing farts in it's general direction but acting like a CB'er and whistling like mad into it I saw around 150mv peak :) Didn't see any distortion looking at the amplifier and Multisim seems to like the numbers as well.

I checked the specs and it looks like the mic will handle 5k ohms max input impedence to the XCVR. and frequency responce starts at 100Hz and starts falling off rapidly at 3Khz

The DN-500 "Commentator" has a response from 50Hz all the way to 10 KHZ :) maybe I should open it up ESSB (Wide 2) Style (50Hz-6.05Khz) :)

I have seen 2 different resistor values going to the 1st stage collector in different copies of the schematic. Some list a 1 meg while others list 10 meg. I will have to open it back up and check for myself :(

Since the output from the first stage is taken off the emitter(emitter follower) I'm pretty sure that stage is just a buffer between the head and the actual amplifier stage.

http://www.nucow.com/image/D104.jpg



BUT you can see that output goes from the center tap of a 5k pot through a 5uf capacitor then a 33k ohm & 800 pf cap(parallel RC) going to ground.
I would guess that the 5uf passes anything over 100Hz and the 33k ohm &800pf shunt the higher frequencies to Ground??