Active Antenna 1-30MHZ - UK Vintage Radio Repair and Restoration Discussion Forum

cinema1 · 25th Oct 2015, 2:04 pm

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

Circuit diagram, photos, all of these will help us. The information given so far is much less then needed for a proper diagnosis.

Ed_Dinning · 25th Oct 2015, 3:48 pm

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

Herald1360 · 25th Oct 2015, 5:53 pm

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.

25th Oct 2015, 2:04 pm	#1
cinema1 Tetrode Join Date: Jun 2008 Location: Preston, Lancashire, UK. Posts: 50	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 Guest Posts: n/a	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.

25th Oct 2015, 3:48 pm	#3
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,194	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
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	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. __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O