Thread: FRG-7 Quiet hum
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Old 14th Jul 2019, 10:56 pm   #1
Anthony_M
Diode
 
Join Date: Jul 2019
Location: Kaunas, Lithuania
Posts: 1
Default FRG-7 Quiet hum

Hi folks!

I had some troubles with my Yaesu FRG-7. One day it went silent. Found & fixed the problem - it was faulty rectifier diode.

While dealing with this issue, I've noticed quiet hum from speaker (when volume is at 0%, or antenna is disconnected). Maybe it was before - just didn't paid attention to it. It's more noticeable while using headphones or trying to record something with a laptop.

I've replaced capacitors. Not all (yet), but majority of them. Few difficult to access - left. But most essential ones (power supply) - replaced.

In everyday use - listening shortwave broadcast stations & hams with speaker - it's almost / completely unnoticeable. But using headphones at low volume levels (<5-10%) humming it's a bit annoying.

I've recorded that hum. Looked at spectrum - it's mostly 50 Hz tone (mains frequency in my country, I'm from Europe).

So... it's normal for 1970s low / mid-range shortwave receiver, or it's something else? Or it's OK and I'm way overthinking this issue?
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