Paul,
I would not use the term "very easy", Joe. It's possible, but I
haven't done so in 27 years with 5 rigs and 3 different D-104s, all
with the stock amplifiers in the base.
You said: "Just crack open the amplifier pot on the bottom enough to
get a bit of audio" ... that's the right way to do it. I've seen (or
heard) too many people turn the pot all the way to the right and it
certainly overdrives the mic preamp in most rigs designed for dynamic
mics. Unlike the K3 that has selectable high and low gain preamps,
most rigs designed for dynamic (~5 mV RMS) mics (Yaesu, Kenwood,
Ten-Tec, etc.) have a fixed high gain preamp *before* the mic gain
pot that distorts if driven by an "amplified" (typically 200+ mV RMS)
mic. The Astatic amplifier is capable of overdriving dynamic mic inputs
if not used properly.
I have also got up to 5 years out of a 9-volt battery, but these
days I change them every January just because.
The reports I had received were different ... notice that the negative
battery lead runs through the PTT switch so the battery is connected
only when the rig is keyed. I suspect the reports of battery drain are
with D-104s that had been modified for VOX.
I have one D-104 with the preamp but it was bypassed (it's also my
"spare" - I need to get re-chromed one of theses days so it does
not get a lot of use). In any case, with the K3, I'd just connect
the preamp power lead to the +8V line on the mic jack and forget
about changing batteries <G>.
73,
... Joe, W4TV
On 11/26/2012 12:31 AM, Paul M Dunphy wrote:
On 11/26/2012 1:09 AM, Joe Subich, W4TV wrote:
Later D-104s manufactured for solid state rigs had an FET amp such as
Don suggests built into the base. You turn the mic over and remove a
few screws to see if it has the amp. It uses a 9V battery that is in
the base as well.
The Astatic amplifier uses bipolar transistors - not FETs. There are
two issues with the stock amplifier ... it uses a 9V battery that does
not last very well and the gain level is rather high (it is very easy
to overdrive the mic input in any rig). The schematic can be found
here: http://www.nucow.com/image/D104.jpg
73,
... Joe, W4TV
I would not use the term "very easy", Joe. It's possible, but I
haven't done so in 27 years with 5 rigs and 3 different D-104s, all with
the stock amplifiers in the base. I have also got up to 5 years out of
a 9-volt battery, but these days I change them every January just because.
If one is concerned, one can replace the stock amplifier with the
one(s) you described. I am not an electrical engineer (as I believe you
are), and all I can do is go by my experience and that of 2 other VE1s
who have done similar to what I have . . . and we are all three DXCC HR
on SSB. In other words, a LOT of operating with that configuration
because we found 25 years ago that nothing beat an amplified D-104 for
punching through a pileup. We haven't over driven any of our rigs. If
you want to rag-chew, then another microphone is likely better. I'm not
an audiophile, and as long as my signal doesn't splatter and isn't
distorted, I don't look for studio or FM quality audio.
I think the OP was looking for the wiring for an amplified D-104
with a T-UP9 base to a K3, not a schematic to make a 50-year old vintage
D-104 work on one. I gave him the pin-out and hookup instructions for
the model he had. Your points are valid, and are probably something
that all users of older microphones should consider when trying to match
vintage accessories to modern equipment. I am not disputing your
expertise or intentions.
73, Paul VE1DX
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