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Old April 2nd 07, 06:29 PM posted to rec.radio.amateur.antenna
K7ITM K7ITM is offline
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First recorded activity by RadioBanter: Jul 2006
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Default What is the purpose of a DC injector?

On Apr 2, 8:09 am, "MRW" wrote:
Good day!

In some of the articles that I'm reading, I keep seeing references to
a DC injector use in RF ports. I really don't know what this means and
what the DC injectors are used for. The only think that I can think of
is for some DC voltage control for a voltage controlled oscillator
(VCO).

Thank you!


Besides the use Philo mentioned, such beasts are also used with
network analyzers to inject a DC voltage (or current) to bias a device
that's being tested. For example, if you want to use a network
analyzer to look at the impedance of a varicap diode, or just to
characterize the capacitance versus reverse voltage of an ordinary
diode, you need a way to put a controlled DC bias on the diode. They
typically consist of an RF choke to feed the DC onto the output
connector, and a blocking capacitor to keep the RF input from shorting
out the DC.

Cheers,
Tom