UPDATED. SEE POST #7.
On occasion, the unfortunate receiver and I hear a very loud, ear-piercing squeal, I'd guess about 1,500hz. Voice modulation is fine, but drowned out by the squeal. What's the cause?
Sometimes hours pass between occurrences, not related to temperature, whether or not the engine's operating, and when the phenomenon starts, the squeal is faint, builds, and a couple of mike keys later is in full swing, then after some period of time, maybe minutes or hours or days, disappears - until the next occurrence.
It's not the SL-30 radio (subbing a -40 didn't help).
Shutting off all electronics other than the radio doesn't help.
Here are some thoughts for rumination:
A weak ground at the antenna, mike jack, coax connector, shielding... but manifestation is much more like a semi failure progression, not a mechanical chatter.
Even though the PS3000 intercom is off, the pilot's mic still passes through, so maybe it remains the antagonist though powered down?
Hmm. I haven't tried another headset (a Lightspeed Zulu 2). That's the first alteration I'll make since the squeal is much like feedback from placing a mic too close to the speaker.
Any "Ah, ha!" moments out there?
John Siebold
On occasion, the unfortunate receiver and I hear a very loud, ear-piercing squeal, I'd guess about 1,500hz. Voice modulation is fine, but drowned out by the squeal. What's the cause?
Sometimes hours pass between occurrences, not related to temperature, whether or not the engine's operating, and when the phenomenon starts, the squeal is faint, builds, and a couple of mike keys later is in full swing, then after some period of time, maybe minutes or hours or days, disappears - until the next occurrence.
It's not the SL-30 radio (subbing a -40 didn't help).
Shutting off all electronics other than the radio doesn't help.
Here are some thoughts for rumination:
A weak ground at the antenna, mike jack, coax connector, shielding... but manifestation is much more like a semi failure progression, not a mechanical chatter.
Even though the PS3000 intercom is off, the pilot's mic still passes through, so maybe it remains the antagonist though powered down?
Hmm. I haven't tried another headset (a Lightspeed Zulu 2). That's the first alteration I'll make since the squeal is much like feedback from placing a mic too close to the speaker.
Any "Ah, ha!" moments out there?
John Siebold
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