Radio and electronics cookbook

[kthorley]

I have just built the Colt 80m receiver from the book. It worked ok when i tested the VFO and Mixer, But when I built the BFO mixer it makes a high pitched tone noise I can hear some mose code and a radio station, but can not listen for long has the high pitched tone noise is to much for the ears. I have tuned the inductor but there is still a high pitched tone noise. It says in the book a high pitched hissing sound should be heard but it is more like a high pitched tone noise I can hear some low hissing noise. Thanks Karl