On Mar 9, 2025, at 9:31?AM, Gordon Gibby KX4Z via groups.io <docvacuumtubes@...> wrote:

?It is possible he’s trying a dynamic microphone

On Mar 9, 2025, at 12:23, K9HZ via groups.io <bill@...> wrote:

?

Bad mic. ?Is drawing the bias provided by RD21 down from 11.9v to 2.1V.?

Dr.?William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

?

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

?

Owner – Operator

Villa Grand Piton - J68HZ

Soufriere, St. Lucia W.I.

Rent it: www.VillaGrandPiton.com

email:??bill@...

?

On Mar 9, 2025, at 9:03?AM, WF4RC Carroll <WF4RC@...> wrote:

?

I have a new sBitxV3 board only. Everything is working except the Mic input. I started experimenting with some microphone I had and the recorded transmission has lots of noise and very low audio. I measure 2.1v on mic input tip. I think it should be 5v. Can anyone guide me as to what the issue may be and where I should look. Here are my measurements/ calculations.?

<sBitx.MicIn.WF4RC.png>

On Mar 9, 2025, at 12:23, K9HZ via groups.io <bill@...> wrote:

?

Bad mic. ?Is drawing the bias provided by RD21 down from 11.9v to 2.1V.?

Dr.?William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

?

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

?

Owner – Operator

Villa Grand Piton - J68HZ

Soufriere, St. Lucia W.I.

Rent it: www.VillaGrandPiton.com

email:??bill@...

?

On Mar 9, 2025, at 9:03?AM, WF4RC Carroll <WF4RC@...> wrote:

?

I have a new sBitxV3 board only. Everything is working except the Mic input. I started experimenting with some microphone I had and the recorded transmission has lots of noise and very low audio. I measure 2.1v on mic input tip. I think it should be 5v. Can anyone guide me as to what the issue may be and where I should look. Here are my measurements/ calculations.?

<sBitx.MicIn.WF4RC.png>

On Mar 9, 2025, at 9:03?AM, WF4RC Carroll <WF4RC@...> wrote:

?

I have a new sBitxV3 board only. Everything is working except the Mic input. I started experimenting with some microphone I had and the recorded transmission has lots of noise and very low audio. I measure 2.1v on mic input tip. I think it should be 5v. Can anyone guide me as to what the issue may be and where I should look. Here are my measurements/ calculations.?

<sBitx.MicIn.WF4RC.png>

On Mar 9, 2025, at 12:02, WF4RC Carroll via groups.io <WF4RC@...> wrote:

?

I have a new sBitxV3 board only. Everything is working except the Mic input. I started experimenting with some microphone I had and the recorded transmission has lots of noise and very low audio. I measure 2.1v on mic input tip. I think it should be 5v. Can anyone guide me as to what the issue may be and where I should look. Here are my measurements/ calculations.?

<sBitx.MicIn.WF4RC.png>