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Microwave Magazine Article on 100 Years of Rvcr Design

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Author Topic: Microwave Magazine Article on 100 Years of Rvcr Design  (Read 681 times)
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« on: March 10, 2019, 09:43:23 AM »

Microwaves & RF magazine, October and November 2018, has a two part series titled 'A Selected History of Receiver Innovations Over the Past 100 Years:



73 de Tom WA3KLR  AMI # 77   Amplitude Modulation - a force Now and for the Future!

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« Reply #1 on: March 11, 2019, 07:36:14 AM »

Thank you for the link Tom.  Quick, interesting read.

Mike KE0ZU

Bold Text and PICS are usually links


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Nico and Chappie (Chappie is the dog...)

« Reply #2 on: March 11, 2019, 12:49:25 PM »

Very nice link Tom, thanks a lot
Here some more info of the Coherer receiver.
At the pic you see a replica of the Meiser and Mertig receiver of 1900 that I did build with the help of information and pics of the real receiver that is in a museum in the UK. They have the only one in existence of this type .
The receiver has a coherer simply made of a small glass tube (1/4 of an inch in diam.) two electrodes glued inside and filings of steel. It is advisable not to use a magnetic steel, the particles have the tendancy to stick together when magnetized . I think I used SS, but I am not sure after a few years. I didn't find much difference in sensitivity using various metals.
I made the polarized relay with an impedance of 3500 Ohms and used a battery of 1.5 Volts. The relay works with 0.8 Volts minimum at approx 250 uA. It has a rotatable magnet aside to cancel the effect of the earth magnetic field and adjust the relay at maximum sensitivity..
The receiver works already with pulses of approx. 10 uWatt and gives out 1 Watt DC at 4,5 V to drive the writer, so it has a comparable gain of 50 dB, quite amazing.
With a small spark transmitter (an original of 1900 used to sell to laboratories in 1900 to investigate the Herzian Waves), I can repeat many experiments as done by Marconi experimenting with antennas and tuning

* coherer receiver 010.jpg (111.47 KB, 780x585 - viewed 132 times.)

* spark transmitter 002.jpg (61.36 KB, 480x640 - viewed 94 times.)

* spark transmitter 003.jpg (53.42 KB, 502x477 - viewed 91 times.)
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