Radio Short Wave DIY Version II
I am a shortwave listener and use to build-up my receivers. This is my homemade short wave radio receiver I built-up some time ago. It is a super heterodyne circuit based on ics AN7223, TEA5570, TDA2822M, w/ J-FET pre-selector in the antenna input. Here I was receiving the 49 meter bcbs stations @ 10:00am (the propagation was not so good at that time). The frequency of local oscillator (generated by the TEA5570) is read by a frequency counter (also homemade). Note that the read frequency is 455khz above the real BCB frequency. The coarse tuning is done by the large variable capacitor and the fine tuning is done by a 100k potentiometer, thanks to a trick, I developed a circuit configuration on the TEA5570 that works as a VCO, without the need to use varactors (tuning diodes). The IC AN7223 does the mixing, IF amp and demodulation jobs. This receiver covers a continuous band from 0.1mhz to 28mhz, I just needed to exchange the coils. Additionally information: this video was recorded in HD 720p, on Sony DSC-H20 camera.
December 14th, 2009 at 1:16 am
Nice workmanship.
December 21st, 2009 at 10:08 pm
Would there be a way of connecting a frequency counter to an earlier model of shortwave radio? Such as, the Realistic Dx-200 or a Knight Star Roamer?
December 22nd, 2009 at 10:49 am
It is possible. First you need the schematic of radio an locate the local oscillator. Then you may pick up the signal of local oscillator coupled via 1pF capacitor to a RCA or BNC connector. Eventually, you will need to install a transistor buffer inside the radio, to amplify this RF signal.
January 2nd, 2010 at 10:26 pm
Most excellent. Could you publish details so that others can duplicate this receiver?
January 3rd, 2010 at 8:28 am
Thank you!
I need to group, organize and digitalize the schematics of all stages of circuitry, because I have it write down in drafts (paper) and some parts are on my mind.
Sure, I will publish and share the as built schematic of this radio as soon as I have finished this work.