D104 Question

[EDWIN J FORWOOD]

All points well taken and agreed.  I had not noticed the hum problem.
However I rarely work close stations on HF.  More usually on VHF.
73 de Jerry, KØEJF

On Wed, 18 Jun 2003 13:08:06 -0700 (PDT) Glen Zook <gzook at yahoo.com>
writes:
> Although my Heath SB equipment will work fine without
> the amplifier, I have found that by using it that I
> can keep down the microphone gain (usually run it at
> about 9:00 o'clock with the preamplifier) which
> results in much lower hum and noise on the transmitted
> audio.  On my SB-110A this is well over 30 dB less
> hum!
>
> The hum certainly meets specifications without the
> preamplifier in use.  But, for example, when I am
> working a local about a mile away my hum level runs
> about S-8 when I am not using the preamplifier.  Of
> course I am a true "60 dB over S-9" on my peaks.  When
> I reduce the gain and then use the preamplifier, he
> can just hear the hum and I am still "60 dB over S-9"!
>  Of course, stations over 3 or 4 miles away cannot
> hear the hum no matter which way I run the microphone.
>
> My Collins S-Lines, on the other hand, seem to have a
> lot more gain in the audio chain and are definitely
> over driven by the D-104 with the preamplifier.
>
> My Heath Apache and DX-100 work fine either way and my
> Hammarlund HX-50A likes the microphone with the
> preamplifier a bit better but will work fine without
> it in use.
>
> Most problems are due to the fact that the microphone
> gain on the transmitter is not reduced by many
> operators to compensate for the gain in the
> preamplifier.  Thus, the audio circuits in the
> transmitter are overdriven and definitely distort.
> Also, like in my Collins S-Lines, in many rigs there
> is already so much gain available that using the
> microphone with the preamplifier engaged is just
> asking for trouble!
>
> That is why I rewired my D-104 with a switch that
> allows me to engage the preamplifier when the rig
> works better with it.  I have a switching box set up
> so that I can use the same microphone on a number of
> different rigs.  Not only do I switch the microphone,
> but I also switch the push-to-talk function on the
> microphone and on a foot pedal as well.
>
> Glen, K9STH
>
>
> --- EDWIN J FORWOOD <e.j.forwood at juno.com> wrote:
>
> While it is true that some equipment may have some
> additional gain when using the amplifier in the base
> of the D104, I have found that none of my Heath SSB
> equipment really need it.  The usual result is that a
> lot of people ruin their audio output due to over
> driving when using the amplifier.
>
> =====
> Glen, K9STH
>
> Web sites
>
> http://home.attbi.com/~k9sth
> http://home.attbi.com/~zcomco
>
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