开云体育

On 03/08/2023 04:23, Roland Turner via groups.io wrote:

With respect to those sound cards which *do* provide mic bias, it would appear that it's a non-issue for Softrocks anyway;

Roland,

Maybe things have changed.

My understanding is that if there is a polarising voltage then the mic input is mono.
In the older laptops this same socket could be switched to a stereo input with no voltage.
Some "professional" sound devices have the 48 volts, usually switchable.

As mentioned often newer devices have a single headset jack with mono input. I do not know if there are any that may be set to stereo input.

These circumstances may be avoided by using a USB sound device, just be certain it has a stereo line input.

73 Alan G4ZFQ

Alan,

On 3/8/23 15:13, Alan G4ZFQ wrote:

My understanding is that if there is a polarising voltage then the mic
input is mono.

Oh!

OK, that explains why there's an issue. Many thanks for persisting.


- Roland 9V1RT

Can I be excluded from this group thanks.
________________________________
From: [email protected] <[email protected]> on behalf of Roland Turner via groups.io <roland@...>
Sent: Thursday, August 3, 2023 12:31 AM
To: [email protected] <[email protected]>
Subject: Re: [softrock40] Getting started

On 1/8/23 17:13, Shirley Dulcey KE1L wrote:

It's best to turn off mic bias if you can. But it won't actually matter to
the Softrock because it has blocking capacitors on its I/Q outputs, so that
bias won't reach the rest of the circuit.

So... why bother?

If you use a fancy interface with
phantom voltage support, turn that off; it's a much higher voltage,
nominally 48V, that could cause issues.

Sure. This is comparable to Power-over-Ethernet, which a friend learned
the expensive way when connecting a cable tracing aid to a socket which
had a PoE-enabled switch behind it.


- Roland 9V1RT

See the links at the bottom of every message. Find several links including one to leave the group. Click or tap on that link to leave the group. You might still get a few messages before that request gets processed.

Bye. Have a good life.

73,

Bill KU8H

I have a Behringer UMC222 usb interface which sells for about $30. It works well with any computer. It is stereo in and 2 chan out on USB. It is 16 bit and samples at e.g. 44k or 48 K. It is much more portable than a fancier Behringer interface. It is good enough that I can use it with a softrock RXII for nuclear magnetic resonance and not just ham radio. You will probably need a stereo 3 mm to RCA adapter cable.
David
K0IMH