Why does my Transmitter Hum?
Posted on March 22, 2005
Because it doesn’t know the words! Or, it could be that you are suffering from one of several technical causes of hum in transmitter circuits…
Because it doesn’t know the words! Or, it could be that you are suffering from one of several technical causes of hum in transmitter circuits…
According to the folks at North Country Radio, there are several causes to consider.
These causes include:
• Power supply hum due to poor DC supply filtering
• AC hum pickup in the transmitter audio due to poor shielding
• Ground loops
• RF induced hum modulation on the transmitted signal
What’s the cure? Here are several links to technical articles dealing with hum reduction in audio and RF circuits:
Hum reduction info from www.northcountryradio.com
Pixie II tips, including hum redux, from www.kenneke.com
Some Tips on Sound Card Interfacing to Your Rig from www.arrl.org
Hum Rejection in Unbalanced Audio Cables from www.bluejeanscable.com
“Tweaks” from Magnan Cables – bottom of the article
Ground loops from www.epanorama.net
Breaking ground loops from www.epanorama.net
Hum Update Listserve for Hams from lists.contesting.com
Circuit tips from the Peg-Legged Bass Pig – middle of the article
Power and grounding techniques from Henry Pasternack
A short primer on RF/RFI & Grounding Techniques by KA7GKN
Happy Hum Hunting!
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