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Homebrew Equipment A place to show, design and discuss the weird and wonderful electronic creations from the hands of individual members. |
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25th Oct 2015, 2:04 pm | #1 |
Tetrode
Join Date: Jun 2008
Location: Preston, Lancashire, UK.
Posts: 50
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Active Antenna 1-30MHZ
Hello ,
Can any one help with the following---- I've built a ACTIVE ANTENNA Frequency 1---30MHZ , Using a small ear -piece to ear for radio signals all i get is a noise in the ear- piece. All the voltages are correct to circuit info, my antenna is a piece long wire 18" long. kind regards. cinema1 |
25th Oct 2015, 2:19 pm | #2 |
Guest
Posts: n/a
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Re: Active ANTENNA 1-30MHZ
Circuit diagram, photos, all of these will help us. The information given so far is much less then needed for a proper diagnosis.
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25th Oct 2015, 3:48 pm | #3 |
Dekatron
Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 8,194
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Re: Active Antenna 1-30MHZ
Just a thought, but have you got the earpiece plugged into the active aerial or into a set that is fed by the active aerial?
Ed |
25th Oct 2015, 5:53 pm | #4 |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,535
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Re: Active Antenna 1-30MHZ
An active antenna isn't in itself a radio. It's a name given to an aerial (usually a shortish whip) that has active electronic circuitry to convert the signal from the whip- a source of indeterminate and highish impedance- to a low impedance (50-75 ohm) suitable for feeding a typical communications receiver.
A good one isn't a trivial design exercise- the electronics has to handle a broad frequency range and cope with high level signals without overloading and generating spurious outputs whilst also passing other low level signals cleanly.
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