[Towertalk] Back-To-Back Diodes - Careful!!
Pete Smith
n4zr@contesting.com
Wed, 04 Dec 2002 13:11:14 -0500
At 09:37 AM 12/4/02 -0800, Ward Silver wrote:
>Danger, Will Robinson! The back-to-back diodes are terrific harmonic
>generators and mixers. If you have strong local BC stations, you will
>cause yourself a lot of grief as these little guys generate their mixing
>products. Also, if you're in a multi-transmitter environment, the local
>interference they generate will also cause a lot of trouble. If you have
>neither of these to worry about - no sweat - but remember they are there.
Hi Ward -- I'm having a little trouble converging two pieces of conflicting
advice. When I asked about receiver protectors, most folks recommended
back to back diodes or strings thereof across the receiver input, as well
as a series resistance or lightbulb.
You're concerned about harmonic generation. Am I right to assume that
harmonic generation only occurs if the voltage applied to back-to-back
diodes exceeds their forward voltage drop? Could you avoid this problem,
then, by stringing enough diodes together so that they limit at a higher
voltage, but one still safely below the rated maximum for the receiver?