UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - FRG-7 Quiet hum

Anthony_M · 14th Jul 2019, 10:56 pm

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?

14th Jul 2019, 10:56 pm	#1
Anthony_M Retired Dormant Member Join Date: Jul 2019 Location: Kaunas, Lithuania Posts: 1	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?