I'm always amazed at the midunderstandings about the poor old D-104. With
proper impedance matching, with an appropriate transformer or a suitable
preamp with the right load on the D-104 element, there's no reason it won't
play well on an SSB radio or an AM radio regardless of the specific radio's
mic input Z.
Elements can go bad (especially the one's you buy that have been sitting for
hours on the hood of a car in 105 deg bright sun summer heat at a hamfest),
the gain on a preamp can be turned up to overdrive the radio, or you can
hook the bare element into a nice low Z mic input on a modern radio. If
those things happen, or you do those things, you get lousy audio. Easy
enough to blame the D-104 for being a crummy mic, rather than admit one
simply doesn't know any better :-)
Grant/NQ5T
> -----Original Message-----
> From: tentec-bounces@contesting.com
> [mailto:tentec-bounces@contesting.com] On Behalf Of Bob McGraw - K4TAX
> Sent: Friday, November 16, 2007 12:27 PM
> To: geraldj@storm.weather.net; Discussion of Ten-Tec Equipment
> Subject: Re: [TenTec] Using a comptuer microphone with a
> Triton 4 (544)
>
> Interesting........ the non amplified D-104 that I use on the
> Collins 32S-1
> always receives "outstanding audio" reports. I guess that's
> due to a crappy
> radio and crappy microphone combination.
>
> 73
> Bob, K4TAX
>
>
> ----- Original Message -----
> From: "Dr Gerald N Johnson" <geraldj@storm.weather.net>
> To: <tentec@contesting.com>
> Sent: Friday, November 16, 2007 10:36 AM
> Subject: Re: [TenTec] Using a comptuer microphone with a
> Triton 4 (544)
>
>
> > On Fri, 2007-11-16 at 07:25 -0600, Bob McGraw - K4TAX wrote:
> >> The D-104 has proven to be a time tried consistent performer.
> >> Unfortunately, many D-104 mike today have an element that
> is defective.
> >> Defective not as in no or low output, but brittle thus one
> that sounds
> >> bad.
> >> New replacements are hard to come by and somewhat expensive.
> >> Replacements
> >> such as the Heil HC-5 work and typically sound good.
> However, to drive
> >> older radios, the amplified base stand is usually
> required. But this
> >> then
> >> is no longer a D-104.
> >
> > The D-104 is a crappy microphone for SSB, always has been. It has a
> > rising characteristic intended (in the 30s) to emphasize
> the highs at
> > the transmitter that were rolled off in the typical AM receiver IF
> > selectivity that had a very rounded pass band. Further the
> crystal and
> > ceramic D-104 were designed to work with a very high
> impedance load for
> > solid state, preferred load a megohm. Today a high
> impedance solid state
> > audio input impedances is likely to be under 100K. That
> load on a D-104
> > changes it from rising to peaked and falling, makes it
> sound muffled. It
> > it still had the rising characteristic with the solid state
> input Z, it
> > can overdrive audio and balanced modulator with audio components
> > rejected by the SSB filter unless in super wide SSB mode
> which draws a
> > lot of fire on the bands.
> >>
> >> Secondly, those with the amplified base stand may have
> their problems
> >> too.
> >> Many due to efforts to configure them to drive different loads and
> >> various
> >> PTT switching arrangements.
> >
> > Or simply from supply VOLTs of audio to an input circuit
> designed for a
> > couple millivolts. NO ham rig has ever needed an amplified
> microphone.
> > Amplified microphones were only needed with fixed transmit
> audio gain
> > CBs that were intentionally very under modulated to
> absolutely prevent
> > over modulation.
> >>
> >> At the same time, in view of all of the above, a good D-104 is an
> >> outstanding performer on SSB and AM too. The following
> link is very
> >> helpful
> >> in wiring the mike, configuring the PTT switching and such.
> >> http://www.shadowstorm.com/cb/Astatic_D-104_Papers.html
> >>
> >> 73
> >> Bob, K4TAX
> >>
> > Yes, I have a D-104 (case) hooked to my Corsair II. The
> cartridge is a
> > Shure limited bandwidth communications element no longer made.
> >
> > 73, Jerry, K0CQ
> >
> > _______________________________________________
> > TenTec mailing list
> > TenTec@contesting.com
> > http://lists.contesting.com/mailman/listinfo/tentec
> >
>
>
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