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Old July 22nd 04, 11:22 AM
Pete KE9OA
 
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I knew there was something I forgot to mention.............the loopstick
amplifier now has a low-pass filter with a 2.5MHz cutoff that follows
the JFET source follower, and a bandpass filter that follows the 20dB
GaAsFET MMIC (this was always there), so when we do market the active
antenna as a stand-alone unit, it should be fairly bulletproof.
After installing the low-pass filter after the JFET, I did notice that
the system gain had increased, so I would surmise that the MMIC was
being driven into gain compression by the multitude of signals in the RF
spectrum. This device has a frequency response from DC to 6GHz.
Also noted before I added the low-pass filter were some spurious
responses from either the FM or TV band. I will characterize this
amplifier chain with a spectrum analyzer later this week, just to make
sure that I don't get any more spurious responses.
Time to go to sleep for a couple of hours...............back to work at
10:00 this morning for another round!

Pete