Possible ground loop problem. If not already connected -at- CN12, try connecting 2, 9, 10, 11 together. Connect 12 and 12 together. And lastly, try connecting 11 to 12 to get all the grounds together.
Mel, K0PFX From: Steven Pemberton <[email protected]> Sent: Thursday, June 11, 2020 2:43 AM To: [email protected] Subject: [Freetel-codec2] Connecting Yaesu MD-100 microphone to the SM1000 Hi all, I've built a box to connect the MD-100 microphone to the SM1000 and retain the mic's extra functions. https://www.dropbox.com/s/71pyjnx01zl1tgd/MD-100%20to%20SM1000%20to%20FT450D.jpg?dl=0 I had thought it was working fine, but a closer examination revealed some odd behaviour. It tests good, but transmits rubbish. Can anyone give me some advice on what I'm doing wrong? I've configured the CN12 patch panel per my diagram, and when connected via the RJ45 to the transceiver it works fine. Connecting a simple external mic also works fine. Both SSB and FreeDV QSOs exchanged successfully. But when I connect the MD-100 to the SM1000 via my patch panel I get odd results. If I connect a headset to the 3.5mm RIG MIC port on the SM1000 I can hear the audio from the MD-100 fine. But when I connect the RJ45 to the rig only noise is transmitted. Even reconnecting the SM1000 directly to the rig via the RJ45 doesn't return it to normal function. But eventually *something* changes and it starts working again! PS/ I've tried with and without JP3 to change the DC bias being sent to the MD-100, but that had no effect. I also thought it might be a problem with line vs. mic level, but I tried an attenuator and that didn't help, and it doesn't explain why the buzz is persistent when the device is cabled directly (until it mysteriously resolves). PPS/ All other features on the MD-100 work fine when connected with the SM1000 in-line. i.e. PTT, freq shift up/down, and fast shift.
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