Hi Guys, A few weeks ago I got an Astatic DN-HZ microphone, it has the button type plug.
It measures 973 ohms DC. I hooked the mike up to the DX-60 and turned the xmtr. to AM
then holding down the CW key transmitted into a dummy load antenna. Didn't hear anything
from the receiver. Does this mike have to low of impeadance?
I was thinking of building an amplifier using an LM 741 opamp and a LM 386 audio amp.
like this.
http://makezine.com/magazine/make-39/electronics-fun-fundamentals-the-eclectic-electret-microphone/Think this would work?
Thanks for any ideas
Gary
The DN-HZ is supposed to be a high output impedance
dynamic mike.
You were probably measuring the DC resistance of the internal low-to-high impedance transformer, so measure with a high impedance DMM, not a VOM, or you'll frap the transformer.
The DX-60 prefers a mike impedance of > 50k ohms. Use a scope and trace the audio from input to modulator cathode. You should not need an amplifier since the mike output should be over 250 mV with a loud "YAYYY."
If the speech amp and modulator are working properly the DX-60 should have plenty of voltage gain.
Do you have good 12AX7 and a 6DE7 modulator tubes?
Phil - AC0OB