[AMRadio] Microphone assistance


Mike Dorworth, K4XM k4xm at arczip.com
Thu Aug 31 20:24:03 EDT 2006


. I was thinking of a transformer in the microphone case and the 9 foot cord
which goes against my grain. I know we can make any of them work. When I
hear AM radio guys talk about HighZ I think of a D-104 and it's ilk at about
5 megohms, this is high Z! When I hear 30K ohms I am thinking of a Hi-Z SSB
like Kenwood TS520s,Drakes and Collins. That is what they call high Z. Most
broadcast mics, I think are about 50 ohms ( dynamic types). I notice that a
Shure 515SB is rated at 150 ohms, actual is 170 ohms and is for use on 19 to
300 ohm inputs..I too like the mixer plan.. 73.. Mike
----- Original Message ----- 
From: "John E. Coleman (ARS WA5BXO)" <wa5bxo2006 at pctechref.com>
To: "'Mike Dorworth, K4XM'" <k4xm at arczip.com>; "'Discussion of AM Radio in
the Amateur Service'" <amradio at mailman.qth.net>
Sent: Thursday, August 31, 2006 5:40 PM
Subject: RE: [AMRadio] Microphone assistance


> You are correct Mike,
> One way to help with the cable capacitance trouble, if a XFMR is to
> be used to step up the voltage, is to put the XRMR close the input circuit
> or preferably in the speech amp chassis and incorporate a 3 pin XLR
> connector.  Run balanced low Z from the microphone to the XLR input and
> using the shield of the cable for just a shield and not common the audio
of
> the microphone.  The mixer is a good plan if available and may have other
> uses.




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