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Old January 4th 10, 09:25 PM posted to rec.radio.amateur.antenna
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Default Sangean ATS-909 external antenna impedance??

On Mon, 04 Jan 2010 14:44:31 -0600, Lostgallifreyan
wrote:

Again, I wonder why they're even there. Isn't it easier to put a gain stage
after the second toroid?


A circuit serves more purposes than gain. Of course, the simple
circuitry found in the file we are discussing has limited offerings.
Of what is offered is controlling input and output Z which is not a
trivial matter.

My preference is found in using Operational Amplifiers instead of
discrete transistors. There is more design flexibility and more
purposes may be served. OpAmps will control input and output Z with
far more rigidity (it is very difficult for externalities to shift
these parameters making for a rock solid design). OpAmps will also
preserve fidelity (faithful phase, magnitude) and not introduce any
distortion, and will drive out noise not already in the signal. Other
advantages can be obtained, but this is enough.

If I put up conspicuous loops here I might get people bothering me about
planning permission or some other means of negative compulsion. If I can
do this with a vertical whip it will be much less awkward.


Practicality needs to be served too. Loops can be useful indoors as
well, and they needn't fill a room. They will test the limits of
balance with the nearby clutter - an opportunity to turn your
environment into an RF lab.

73's
Richard Clark, KB7QHC
 
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