heil pro 7 electret microphone

Dave - WB5NHL

Is anyone using a Heil Pro 7 with the electret element and the Flex 6500. I am using the AD-1-Y cable and turned on bias. I get no microphone input.  I measured pin 2 on the mic connector and it shows 4.9 volts with the bias setting both on and off!!!  

ctate243

try using a stereo to mono adapter on the mic input jack and see if it starts to work.  This is how I got the CM-500 to work.

Lawrence Gray

I think it needs to be mono.  I use a Koss SB25, which has an electret element requiring bias.  It didn't work until I used a stereo to mono adapter.  I use the Heil cable adapter with this headset.  I like it because it is light, fits me well, and has great frequency response.  I can also use it with Parallels to run the 6500 remotely.

Dave - WB5NHL

The mic connector from the Pro 7 is 3.5mm mono.  The phones are 3.5 mm stereo.  Yes, this is the way I've plugged them in.

Dave - WB5NHL

From another posting

There are two sources for Bias on the 8-pin Foster connector: 
There is an always on 5V sourced through a 560 Ohm resistor to pin-2 as shown below. 
You can also turn on the Mic Bias in the GUI that turns on a 2.97V source that is applied to pin-8, which is the microphone hot lead.

I've made sure the mic connector is properly connected to the Flex.

I've checked both of these and they are there.  I have also used a friends Pro 7 and AD-1-Y cable with no change, still no mic input.   I also used my Pro 7 with my IC 7100 (with appropriate Icom cable) and the headset worked fine.

I'm getting close to the end of the rope hi hi.

Lawrence Gray

I had an issue with a profile setting turning off mic bias?  

W7NGA

Dave, I have had this issue occur and I had to remove the Foster connector, re-insert it, push, wiggle it, and was ultimately successful. There seems to be a slight spacing issue that surfaces at times. Once the sweet-spot is found it works well and works reliably as long as a profile doesn't disable bias unexpectedly. 

Dave - WB5NHL

Yes I'm sensitive to the Foster connector issues. Last night I did some more testing. I confirmed the pin 8 bias on the Foster. I then confirmed the bias across the connector in the AD-1-Y cable. I then confirmed the bias voltage on the pins of the electret element in the headset. However, with the electret element installed I see no bias. Voltage drops into miilivolts.  I know the element is good since it works on my IC7100.
I'm beginning to suspect the bias source in the Flex???

Dave - WB5NHL

Nailed it down.....  Problem with bias source.   A friend measured his bias voltage with the element installed as 1.57v    Trouble ticket here I come.