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My Home Constructed Portable Solid State SW And FM Superhet Receiver.MP4

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Uploaded on Nov 24, 2010

My Home Constructed Portable Solid State SW And FM Superhet Receiver.MP4 This is a solidstate version of my latest single conversion FM/AM Shortwave superhet receiver configurations using pulse counting technology. The Semiconductor lineup is as follows. The VHF RF AMP is a cascode tuned RF stage using 2x 2N3819. The VHF mixer uses 1 BF244B and the VHF local oscillator uses a BF244B Hartley Oscillator. The IF amplifier uses 2 BC547s and are cascaded resistance coupled amplifiers set at a frequency responce of about 150KHZ. The limiter and diode pump detector consists of 2 BC547s and 2 1N4148 silicon diodes. The Audio output stage is a LM380N. In SW/AM mode the VHF Mixer/IF section serves as a 455KHZ IF amplifier and the band selector is wired in an ingenius way to perform 3 functions as discribed. The first pole switches the VHF RF coil to a 455KHZ IF Transformer and the second pole disables the positive 9V supply to the VHF local oscillator/RF Amp and is then switched over to the SW mixer and Oscillator section to form a shortwave receiver configuration. The third pole simply switches the telescopic antenna from the VHF RF amp to the Shortwave mixer coil. The semiconductor lineup for the shortwave section is a BF244B local oscillator using souce feedback mode and the SW Mixer is a dual channel 40673 MOSFET. An IF gain control on the IF amplifier has been included to reduce the static pulses when using AM and as a result the pulse counting detector can form as a very good voltage doubling AM detector as well as detecting FM signals. This is my first solidstate homemade receiver to be constructed in a aluminium case and I must say, as a result there are no hand capacity effects due to the fact that metel forms a good ground plane. The disadvantage is the sound from the internal speaker is a bit tinny but alright for a go anywhere portable receiver. As you may not notice any speaker at the front panel, it has been located at the back of the case. More information and construction details can be found on my following webpage http://philsvalveradiosite.co.uk/phil...

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