[K2] Interfacing a DTMF Pad

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[K2] Interfacing a DTMF Pad

Phil Kane-2

I need to interface a DTMF pad to the mic input for special-purpose
signaling but  I have not yet found a desk mic that has DTMF capability
built-in. Has anyone had any experience doing  that?  If an external pad
is required (I have one floating around here somewhere), how can it be
done?    Will a simple Y connection suffice?

73 de K2ASP - Phil Kane
Elecraft K2/100   s/n 5402

From a Clearing in the Silicon Forest
Beaverton (Washington County) Oregon
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Re: [K2] Interfacing a DTMF Pad

Don Wilhelm
Phil,

The only problem with a simple Y connection is that the mic will be
'live' when using the DTMF pad.
If you need an attenuator, try a 100k in series with the cable and a 10k
from the line to ground.  Those values are high enough not to interfere
with the mic.  Adjust the value of the 100k so you just light the ALC
one bar.

You may have to turn compression off if you do not get a clear DTMF
signal out of the RF.

The alternative is to get a DTMF microphone and rewire its plug to match
your K2 mic configuration.

73,
Don W3FPR

On 7/14/2020 4:22 PM, Phil Kane wrote:
>
> I need to interface a DTMF pad to the mic input for special-purpose
> signaling but  I have not yet found a desk mic that has DTMF capability
> built-in. Has anyone had any experience doing  that?  If an external pad
> is required (I have one floating around here somewhere), how can it be
> done?    Will a simple Y connection suffice?
>
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