Audio input oddity

Rich McCabe

Have an odd quirk with my 6500. I feed my radios with a W2IHY iPlus. If I have the switch to another radio when starting SmartSDR  and the change the iPlus switch I get no audio. I have to shut off Smart SDR and restart it before I get audio.

I am running balanced line for mic input.

It seems the radio needs mic connected prior to SmartSDR start. Does that seem right?

At first I thought the switch was going bad in my iPlus. LOL

Rich

Jim Gilliam

When you first start up and you have no switched audio from the iPlus, what is your default record setting in Windows?

Jim, K6QE

Rich McCabe

Record setting?  I am not running audio through a PC.

Mic>iPlus>Flex 6500

Mike - ZL1MRC

I have the same problem.  Running a flex 6500 with a Iplus connected to a IC7600 and the Flex-6500.  If I change from the IC-7600 to the Flex-6500 I get no Audio input to the Radio.  After a few seconds audio returns.  If I go from the Flex to the Icom I don't have a problem.  As above I am running a balanced input.  

73
Mike - ZL1MRC

Rich McCabe

Good info. Mine has returned a few times on its own as well so it made my diagnosis hardard, but did not put it together until yesterday.

Maybe flex will chime in, but appears you need audio input on the balanced input before starting smartSDR.

Tim - W4TME

It seems the radio needs mic connected prior to SmartSDR start. Does that seem right?

I just verified that the radio will start fine without a mic connected, regardless of the mic input selected.

Ken - NM9P

Rich, you said that you are using balanced line.
I assume you are using the Balanced (XLR-1/4 inch TRS) input, and not the 8-pin front panel input.

But which setting and level are you using for your input to the rig?
Are you using the BAL connection at Mic Level (using BAL setting)... or at Line Level (Using LINE setting)?  

I don't think there is really any difference between the two, other than that LINE will not let you turn on the +20 dB Mic Gain.  I used BAL mode even when using Line Level from an external mixer.  I just turned the +20 gain OFF.

If you are using the 8-pin input, you might need to check that the BIAS button is turned off.  

I can't think of any reason it should behave as you describe, unless perhaps there is some voltage change between the two settings on your iPlus.  Perhaps it is interacting with the rig Bias Circuit?  Or rig bias voltage is charging a capacitor in the iPlus when it is not selected and preventing audio flow?

Just thinking out loud here....What does the iPlus do when a rig is selected or un-selected?  Is it an open circuit, a short circuit, is there a transistor/digital audio switch involved?  

Ken - NM9P

Rich McCabe

Ken,

Yes 1/4" into the back XLR connector.

I do not understand the line input vs balanced on the flex. Both work identical for me and same slider level gives me the same amount of audio.  And in my case I can turn on the 20db gain on both settings.

I talked to Julius/W2IHY and he wants to try an experiment related to "decoupling in the PTT" and is sending me another cable.

One thing I just realized is there IS audio but its not making enough power to show on my wattmeter and the locals tell me its distorted audio. Wait 5 -10 seconds and it works again.

I can switch iPlus to another radio and wait 5 seconds and flip back to Flex and have same issue

Rich
kd0zv

Mike - ZL1MRC

Hi Rich
I am having the same issues.  I have tried two cables both supplied by W2IHY.  One is to the balanced input and the other to the Microphone port on the front of the flex.  Both have the exact same problem.  

If you like I could try and record the audio from the Flex Mic DAX.

Mike.

Rich McCabe

Mike, I sent Julius your comment.  He is shipping me a cable today so will let you now if that helps.

Rich

Tim - W4TME

I do not understand the line input vs balanced on the flex. Both work identical for me and same slider level gives me the same amount of audio.

Electrically, they are identical except for the connector.  By default the XLR (balanced) connector has the +20 dB mic preamp enabled because it is intended to be used with a balanced dynamic microphone that has a low output gain level.

The Line level input does not have the +20 dB preamp enabled because it is intended to be connected to outboard audio processing equipment (mic preamp, channel ****, effects processor, etc...) and that equipment has much higher output gain than a microphone.

Yes, you can enable or disable the +20 dB preamp on either the Line or Balanced connections.  This is covered in the FLEX-6000 Hardware Reference Manual.

Rich McCabe

As always, thanks Tim. That makes perfect sense. 

But isn't the line in connector the same as the balanced connector or are  you considering the balanced the XLR and the Line in the 1/4"?

I have been running the  1/4" since day one and have just considered it a multi use balanced connector.

Tim - W4TME

Line = 1/4" TRS
Balanced = 3-pin XLR

Since they are electrically equivalent, both are balanced inputs

Mike - ZL1MRC

Rich, thank you for the update.  Please keep me posted.

73
Mike

Rich McCabe

Mike appears it has something to do with the capacitor bleeding off on the Icom cable when you switch

Resolution coming.

Rich

Mike - ZL1MRC

Hi. Excellent news. Please keep me posted. 73 Mike

Rich McCabe

According to W2IHY he uses a 100 uf  electrolytic capacitor to block the DC voltage on the audio line of an Icom.  He is wondering if the cap is charged and the Flex does not like that cap discharging when we switch to it.

I sold my 7800 Friday but still have a Icom 9100 on iplus position 3. The flex is on position 2. I can switch from empty spot position #1 to the Flex and have no issues. But cant switch from the 9100 in position 3.

I am sure Julius will figure it out. Have never met anyone with better support.

Rich

Rich McCabe

Mike the fix is solder a 1k resistor from the audio pin on the DIN connector to the next pin over (ground) on the back of the W2IHY unit.

The 6000 series does not appear to like the capacitor discharge when switching from an Icom to Flex.

Julius is going to start shipping Flex cables with the 1K resistor.

73
kd0zv

Mike - ZL1MRC

Hello, ok will do.  Could you please let me know what the pins are the Audio and Ground pins are.
Thank you
73
Mike

Rich McCabe

Mike - ZL1MRC

Hi, confirm that the fix has resolved the problem.  

73
Mike

Rich McCabe

Great !

Rich McCabe

Just to make sure I dont confuse things. The above drawing is from Julius W2IHY and shows 1k to 5k .  That drawing was done before I did any testing for him.  A 4.7K resistor DID NOT work for me.

A 1k resistor did work and had no noticeable attenuation of audio. 

So the proper resistor is 1K and all Flex cables he ships going forward will have 1k built in from audio to ground.