?

You do realize that the socket is a 4-conductor not a 3-conductor like a stereo socket, right?? One of those lines has voltage on it for the microphone.

tip = speaker

ring1 = data/clone

ring2 = mic/ptt (this will have a DC voltage on it)

sleeve = ground

73 de AC7EW

Kelly

On Fri, Mar 11, 2016 at 6:26 AM, rick.levine@... [FT-60] <FT-60@...> wrote:

Hello all!

Have any of you put a decent set of headphones on your FT-60?

I got around to wiring up a mono adapter for the speaker mic headset socket on mine, and on a lark shortened the cable on a spare set of Sony cans, figuring better isolation and better audio wouldn’t hurt.

The ugly surprise was a very loud “thump" whenever the FT-60 unmutes and mutes. I measured the DC offset, and it’s almost 3 volts! I can probably put a capacitor in the line as a high-pass filter, but I’m wondering if this is normal, and if any of you have run up against the same problem?

The noise I’m hearing isn’t the squelch “crash” noise, but is from the DC voltage that the radio throws on the audio output when it unmutes. (If I turn the audio all the way down, and press the button on the side of the radio to open squelch, I’ll hear the thump.) It goes from no DC voltage when muted to almost 3 volts unmuted. The headphones I’m using (Sony 7506) can handle a lot of power, have large diaphragms, closed earpieces and can nominally reproduce audio down to 10hz. When the DC hits them, they do something with it, slamming the diaphragm hard, producing a nausea-inducing thump. The good news is that I don't blow the drivers, the bad news is that I’ll have to find a solution to make them usable for long sessions.

(I gave Yaesu a call, and they noticed the problem, too. They’re sending a query to an engineer for advice, but the guy I talked to didn’t hold out much hope for a fix, as the FT-60 is getting pretty long in the tooth, and they don’t prioritize engineering for it.)

Thanks!

Rick

KK6WHJ