Was the D-104 a good match to an SB-101?

[Glen Zook]

I don't have an SB-101 but do have an SB-110A which is
very similar except that it is for 6 meters only.

Since I use my D-104 with quite a number of "boat
anchor" equipment I modified it so that I can either
use the preamplifier or come directly off the
microphone element.  This was done by installing a
DPDT toggle switch in the microphone base.

I have found that my Heath SB-110A and my Heath SB-401
both like the use of the preamplifier better than just
the microphone element by itself.  There is no
distortion, etc., and the audio gain of the Heath
units is at the 9 to 10 o'clock position.  If I run
the microphone without the preamplifier I have to run
the audio gain at 3 to 4 o'clock.

My Collins S-Lines, on the other hand, are MUCH
happier without the preamplifier!

One thing that I have found is that the 9 volt battery
needs to be in very good shape.  The D-104 tends to
"eat" batteries on a regular basis.  If the terminal
voltage of the battery starts to drop, the audio does
start to get distorted.  About a month of "average"
(whatever that is!) operation (actually about an hour
or so in the evenings) and the battery needs
replacing.  Or, a good SSB contest weekend and it
needs replacing!

I have thought about replacing the battery with a good
"wall wort" type of supply.  However, the filtering of
the power supply would have to be very good to insure
that no additional hum is placed on the audio.

You do need to be careful as to how you set the audio
gain from the microphone when using the preamplifier.
I have found that running it no more than 50% works
best.

Glen, K9STH


--- "Randall C. Iliff" <riliff at COMMSPEED.NET> wrote:

Would a normally functioning D-104 crystal mic provide
enough output to drive the SB-101 if it too were
functioning properly?  Right now I get lousy SSB drive
using the bare mic at full input gain, or distorted
audio if I resort to the amplifier that Astatic built
into the base.

=====
Glen, K9STH

Web sites

http://home.attbi.com/~k9sth
http://home.attbi.com/~zcomco

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