The stock D-104 requires a very, very high impedance for it to operate
with its designed frequency response curve. Depending on the vintage of
the crystal element it works best from somewhere between 1.5 meg and 3
meg input load impedance. When the mic element is swamped down into a
much lower load value the microphone output takes on a very pinched
sound with little lows or lower mid range audio. This may sound ok to
some when used for DX or contest type operation but under normal chat
communications it will sound very thin and easily over-driven. The
impedance of the Paragon mic circuit is from somewhat to significantly
less than 1 meg depending on the capacitive reactance of a capacative
voltage divider. Check the schematic to see what the D-104 is looking
into. Certainly not as bad as other 'modern' transceivers but still not
what the Astatic crystal element was designed to work with.
Check out the following link:
http://members.cox.net/n4jk/d104.htm
This was the buffer amplifier that I put in my D-104. The resultant
audio is rich with fulness with the slight upper mid-range bump in
frequency response needed for voice clarity. I have compared,
on-the-air, a stock un-amplified D-104, a stock amplified D-104, and my
modified D-104. Not trusting to other's opinions I did multiple
recordings with my voice keyer and then transmitted from the Omni-VI+
and the Paragon to my Jupiter with the audio openned up. The difference
was more than remarkable and turned many a skeptic back toward the D-104.
Have fun!
Jerry, KG6TT
>I have used my D-104 (vintage, stock and non-amplified version) with my Omni
>6 Plus for years with great results. I would imagine that the tx audio input
>for the Paragon is similar to the OMNI 6 Plus and therefore should work very
>well. I would avoid the newer "amplified" D-104's.
>
>
>
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