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
>
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