8400 Microphone requirements

Doug

The document says to use a dynamic microphone. Does that mean any dynamic microphone? Anything special I need to be aware of?

KD0RC

Hi Doug, the Flex 6000, 8000 and Aurora series will all accept dynamic or electret mics. The thing to be aware of is the pinouts of the mic connector and any power requirements for electret (condenser) mics. Be sure to create your own Mic Profile for each mic that you use with your Flex. That way the defaults won't overwrite what you have whenever you upgrade.

Mics that take "phantom" power will normally need a separate supply (typically high-end studio mics). Electret mics designed for use with computers can normally be used with the bias voltage supplied by the FLex.

For my desk mic, I use a Heil HM-12. It is a dynamic mic with a balanced output. I have a Flex cable that takes that and turns it into pseudo-balanced for my 6400. It also works the same with my 8600.

I also have a Yamaha CM-500 headset with an electret mic I built a simple adapter into a 3.5 mm plug housing.

Here is how I did it:

https://community.flexradio.com/discussion/8023958/cm-500-headset-blocking-capacitor-value

Doug

I have tried two different studio dynamic mics. I needed to turn the microphone gain up to a relatively high level. While listening through headphones, as I turned the gain up to get enough drive, there was quite a powerful hiss in the background. This rendered these mics unusable. I plugged in a Heil headset, which worked perfectly. I have a Heil HM-12, which I would like to use. It has a 4-pin connector. I have a 4-pin plug to fit it. But I don't know the pin-out for the microphone. Hopefully, the HM-12 will be compatible. I don't understand why the studio mics don't work.

The 6300 (which I am very fond of) has a Yaesu-compatible microphone jack on the front. Many years ago, I wired up a conversion cable that allowed an Icom microphone to work with a Yaesu radio. I used a Heil ICM mic with the 6300. It worked perfectly.

So I'm stuck. Common studio-type dynamic mics DON'T work with the 8400. They do not have enough output to meet the needs of the 8400. Raising the mic gain enough to get proper modulation introduces this unusual background hiss.

Rick N4RZ

Have you tried turning on the +20dB boost for the microphone?

Doug

I don't see a 20db boost anywhere. Where is it?

Doug

I found a solution to my problem. I had been using a1/4" to 1/8"adapter to fit the mic input on the 8400. I had used a 2-conductor 1/4" from the microphone to a 3-conductor 1/8". That was a mistake. That caused a great deal of noise to be introduced into the audio. When I switched to a 2-conductor 1/4" to 1/8", the noise disappeared. Now everything works perfectly.

Rick N4RZ

The +20dB microphone boost control in SmartSDR is located in the Radio Setup menu. Here is how to access it:

• In SmartSDR, navigate to the Settings menu.
• Select the Radio Setup tab.
• Go to the Phone/CW section.
• Within this section, you will find a checkbox or option to enable the +20dB Mic Boost. 

This setting adds 20 dB of additional gain to the microphone input and is commonly used with dynamic microphones that have a lower output level. It is generally not needed for most electret microphones. You can find more detailed instructions in the Adjusting your Microphone Settings for Best TX Audio guideon the FlexRadio HelpDesk. 

Mike-VA3MW

2 great videos here to help you out:

https://www.youtube.com/live/koK3pQZh3qs?si=nA-ZWvB-TVh3JO06

https://youtu.be/GdFeTzPo14w?si=aSsSd6F9s6gNE_q4