Crystal Radio Circuits - Alternative Concepts

 1. Parallel-tuned, series-fed configuration:

Parallel-tuned, series-fed Crystal Radio circuit

The diode-clipped parallel-resonance voltage is output to the phones. 

High-impedance diodes and phones are required to match the high impedance of the parallel-resonant 

circuit. 

This configuration is suitable for reception of distant, weaker stations.

   
2. Series-tuned, shunt-fed configuration:

Series-tuned, shunt fed Crystal Radio circuit

The diode-clipped series-resonance current is output to the phones. 

Low-impedance diodes and phones are required to match the low impedance of the series-resonant circuit. 

This configuration is suitable for reception of nearby, more powerful stations.

3. Series-tuned, shunt-fed variant:

Series-tuned, shunt-fed Crystal Radio variant

This is a variant of the above series-tuned, shunt-fed configuration. 

Using low-impedance diodes and phones, it delivers identical performance.

Related post: Parallel-tuned Compact Loudspeaker Crystal Radio

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Remembering OM Joe - VU2JA

My memories go back to a day in the year 1976 when OM Ramesh - VU2NRS and I had an eyeball QSO with OM Joe - VU2JA at his shack on # 20, Union Street, Bangalore.

It was in an imposing building with a tiled roof.  More imposing was the antenna, strung well clear of the roof, between two tall ground-mounted masts.

On the huge wooden shack table was an open-frame vacuum-tube CW rig, coax-coupled to a big open-frame transmatch mounted on the wall. Entry of the ladder-line feeder into the shack was through a ventilator high up on the wall. The sight of  the homebrew transmatch, with its neat copper coil and variable capacitors, is still etched in my memory and so is Joe’s characteristic CW sending.

OM Joe - VU2JA - Courtesy 73 Magazine

Joseph Alexander Faithful was born on 11^th April 1898 in Calcutta. In the year 1914, working as a deckhand for his passage, he sailed to England to take up a course in Mechanical Engineering. But fate willed otherwise. War broke out when they neared Hamburg. Joe was also taken prisoner and released only six months after the war was over.

More on his incarceration at:

http://britishlibrary.typepad.co.uk/untoldlives/2013/07/joseph-faithful-an-anglo-indian-internee.html

In England after his release, Joe qualified in wireless telegraphy and, after a fulfilling career, retired and settled down in Bangalore.

Joe married Hildred Joyce Dique at Karachi in the year 1934. They had no children.

More details including that of his career and ham radio activities at: http://www.ncdxc.org/newsletter/1975/DXer050675.pdf

He was an Amateur Wireless Pioneer, a member of the Old Old Timers Club, USA (OOTC # 695).

OM Joe passed away on 25^th January 1985. Hildred followed on 31.10.1988, bequeathing their property, to the following in Bangalore, for religious and charitable purposes:

Little Sisters of the Poor, Missionaries for Charity, St. Michael’s Convent, Christu Seva Samaj, St. Mark’s Cathedral, Bangalore Cheshire Home, Bangalore Children’s Society, Kidwai Memorial Institute of Oncology, St. John’s Medical College & Hospital.

Memorable lives indeed.
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