Project Solutions (2011/07/24)
Index
High-End-Preamp （6）
Published:2011/7/24 22:54:00 Author:Amy
By Benjamin Hinrichs Stable supply A large part of the stabilisation, decoupling and hum suppression for the supply voltages takes place locally on the main circuit board, for both the digital portion (+5 V) and the analogue portion (5V). The only other thing you need is a sufficiently stable source of symmetrical DC voltages (which shouldn’t be a problem with the low current c... (View)
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DIY RF Inductors--The ABCs of inductors （2）
Published:2011/7/24 22:52:00 Author:Li xiao na
By B. Kainka Inductors with cores RF inductor forms with threaded ferrite cores are often used in practice. The core increases the inductance, typically by a factor of four or even more. The inductor can be tuned by adjusting how far the threaded core is screwed into the inductor. Ferrite cores are made for specific frequency ranges, within which they exhibit small energy losses.
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High-End-Preamp （5）
Published:2011/7/24 22:37:00 Author:Amy
By Benjamin Hinrichs Channel switching The input channels are switched on the relay board. The circuit shown in Figure 3 allows two different wiring options. With the traditional option, all eight inputs from the Cinch sockets are used, with a single output to the main circuit board. This requires JP2 and JP3... (View)
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Propagation - the total surprise factor
Published:2011/7/24 22:36:00 Author:Phyllis
The propagation of radio waves is a fascinating phenomenon because most of it is guessv/ork and sheer surprise. That is not to say the subject has not been studied extensively by researchers and radio amateurs — far from it, a number of underlying principles have been described in scientific terms as early as the 1920s by Nobel Laureate Sir Edward V. Appleton (1892-1965). Appleton discovered thai radio waves, depen... (View)
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DIY RF Inductors--The ABCs of inductors （1）
Published:2011/7/24 22:29:00 Author:Li xiao na
By B. Kainka Electronics hobbyists often wish to copy a circuit for which suitable coils or fixed inductors are not readily available. However, you can wind just about any type of inductor if you only know how. Or you can take inductors from old equipment and modify or adjust them. All you have to do is determine is how many turns you need. 
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A dipole antenna for 4 meters （2）
Published:2011/7/24 22:23:00 Author:Phyllis
Receiver sensitivity measurement With the generator tuned to the receiver (or was it the other v/ay around?) a great moment arrives — v/e’re ready to decrease the RF output level on the generator until the receiver under investigation loses the signal. The VHF-Low Explorer not having an adjustable squelch or squelch defeat switch, the transition from ’very noisy signal’ to ’muted’ was found to be... (View)
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A dipole antenna for 4 meters （1）
Published:2011/7/24 22:12:00 Author:Phyllis
No receiver is complete without a matching antenna. Commercial offerings for the 4-m band being few and far between (or scrapped by PMR fleet owners), we decided to present a design for a low-budget get-u-going dipole. Not sophisticated, want a directional antenna? Then try the links at the end of this article. Too difficult? It doesn’t get much simpler than this, so give this antenna design a try and you’ll be ple... (View)
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High-End-Preamp （4）
Published:2011/7/24 21:30:00 Author:Amy
By Benjamin Hinrichs The multitude of options for constructing your ’personalised’ high-end preamplifier mean that you must read this second part of the article before you order the parts and take up your soldering iron. This is because your requirements determine how many circuit boards of which type you will need, as well as which components you will need. You can con... (View)
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