A long time friend of mine who have cancer asked me to sell all his
amateur equipment. I have now an excellent good looking Silver Eagle
microphone, probably will become a piece of collection, who knows.
I just wondering if anybody try with success to use this microphone
with their K2 ???
73
JEAN-FRANÇOIS MÉNARD / VA2VYZ
=
I assume that's an Astatic D-104 Silver Eagle, Jean-Francois, sometimes
called a lolly-pop microphone because of its distinctive shape. If so, it
should have an amplifier built into the base (turn it over and there'll be a
place for a battery and a screwdriver adjustment for the gain). That mic
with the amplifier will drive a K2 beautifully. Avoid over-driving the K2
though. That amplifier has plenty of gain. If you set it up so you get a
little ALC action (shown on the bar graph in ALC mode) on the band that
needs the most audio (usually 10 meters) at full RF power out, it should be
fine. If the adjustment seems touchy because it's near the low end, don't
forget you can switch in an attenuator in the K2 using the Menu. Set SSBA to
1 for about 10 dB audio attenuation.
The D-104 is not a good mic to use with the K2 if it lacks the amplifier.
The D-104 uses a crystal element designed for a load impedance of about
50,000 ohms. That was very common for tube-type audio inputs half a century
ago, but modern gear, like the K2, expects an impedance in the range of
1,000 ohms. That's why Astatic started incorporating the amplifier in the
base of their later microphones.
If you don't have the amplifier and try to use the mic, you will find that
the audio frequency response is very different than what you'd expect due to
the impedance mismatch and the audio level will probably be quite low. In
that case you could try a matching transformer, if the mic has enough output
to drive the K2 without the preamp.
Ron AC7AC
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