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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!