[CQ-Contest] SO2R audio spike problem

[Grillo's]

Where can I get one of these boxes?

----- Original Message ----- 
From: "David A. Pruett" <k8cc at comcast.net>
To: "Barkey, Patrick M." <pbarkey at bsu.edu>; <cq-contest at contesting.com>
Sent: Friday, February 06, 2004 4:09 PM
Subject: Re: [CQ-Contest] SO2R audio spike problem


> Pat,
>
> I wonder if this has something to do with the fact that ICOMs have +8V on
> the mic pin of the radio for use with electret mics?  This voltage is not
> required for non-electret elements such as the Heil (either DX or
> standard), and indeed should be blocked with a capacitor of 0.22uF or
greater.
>
> The Heil ICOM adapter (from sub-mini jack to 8-pin plug) has the blocking
> capacitor built in.  If you've built the two-radio switch box just like
the
> schematic, and you're plugging the Heil in directly, your mic is seeing
> +8VDC on it.  The "pop" you're hearing on switching may be caused when the
> mic connects, and loads down the +8V supply.
>
> If one isn't present already, I would add a blocking capacitor at the jack
> where your Heil plugs into the switchbox.  This will block the +8VDC from
> getting both to the headset and the DVP.  The latter probably doesn't need
> the protection, as I'm pretty sure it's capacitively coupled.
>
> The cap value is non-critical - anything over .22uF and rated for 8VDC or
> more is OK.  An electrolytic is OK too - I would put the + end towards the
> radio.
>
> 73,
>
> Dave/K8CC
>
>
> At 03:06 PM 2/6/04 -0500, Barkey, Patrick M. wrote:
> >I've been running a pair of IC-765's with a N6TR-style
> >two radio switch box for quite some time.  This is the
> >one described in http://www.kkn.net/~k5tr/trlog/switch.pdf
> >
> >I have noticed on SSB for some time that whenever I
> >switch between radios, the VOX on the radio I am
> >switching towards pops.  I have a very short delay, so
> >this is not a big deal.
> >
> >The problem is this.  Many times after switching my mike
> >to radio #2 to work a multiplier, and then back to radio #1
> >to call CQ, I loose audio output from my microphone
> >and my DVP entirely.  It will be dead for about 5-10 seconds.
> >
> >If I leave the VOX off on both radios, this never happens.
> >But I like to use VOX, so this isn't a great solution.
> >
> >I am using a Heil Pro-Set mike with a DX element.
> >
> >Anybody got any suggestions for a solution?  Thanks.
> >
> >   - Pat
> >     N9RV
> >
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