From: "Al Parker" 
Subject: Re: e: [drakelist] T4XC and D104


"Al Parker"  made an utterence to the
drakelist gang
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Hi agn,
    A thought occurred to me after I posted on this subject last nite -
The Astatic amp may serve another purpose that was also unintended.  Most
of us have seen the xtal cartidges lose their output, the amp will extend
the life of those.  What're we gonna do when the somewhat limited present
supply of new cartridges is gone?  I bought 3 or 4 abt 4 yrs ago (from a
CB source), only have 1 left as unused.  I"ve heard that the Heil #5 is a
good one, but somebody on this thread didn't like one of the Heils, maybe
the 4.  He wasn't selling just cartridges a while ago, hopefully he'll go
back to it.  I think they had broken a die & were having another made, but
that was several mo.s ago.
    Other than that, I go along with Jim.
73,
Al, W8UT
New Bern, NC
BoatAnchors appreciated here
http://www.thecompendium.net/radio/
http://www.hammarlund.info

----- Original Message ----- 
From: "Jim Shorney" 
To: 
Sent: Thursday, August 05, 2004 5:18 PM
Subject: Re: e: [drakelist] T4XC and D104


>
> "Jim Shorney"  made an utterence to the
drakelist gang
> ----------------------------------------------------------------------
> On Wed, 04 Aug 2004 21:18:47 -0700, Grant Youngman wrote:
>
> >Impedance matching is in part the reason for the preamp in the first
> >place.  Except that even the Astatic preamp doesn't have a high
> >enough input impedance to get the D-104 to sound as good as it
> >can.  That can be fixed by simply increasing the value of the input
> >resistor on the preamp.  Many alternate simple preamp designs,
> >some with variable input Z to allow tailoring of the mic's response
> >are around also.
>
>
> If that's the case (and I'm not doubting anyone's word here), it should
> be a simple matter to brew up a good low-noise op-amp configured as a
> unity gain amplifier with a suitably high input Z. Hang a pot across
> the output to attenuate in case the mic output is too high for those
> newer rigs. This I could be comfortable with. No need for a pre-AMP, in
> any case. Just a Z-matching buffer.
>


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