Kth - sdr - kit

6/13/2010 KTH - SDR - KIT Page 3
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Read this manual attentively before starting assembling the kit, even if
you are an experienced engineer!
1. Overview.
The KTH-SDR Wideband receiver kit 1021, is a Direct Conversion Software Defined Radio covering the
following frequency bands:
• HF - covering 3.5 MHz through 32 MHz.
• 6 meter band - 50 through 52 MHz or 50 through 72 MHz.
• 2 meter band - 144-146 MHz or 137-138 MHz (optional).
• 70 cm band - 430-440 MHz.
The SDR receiver is designed to work as an “All modes” receiver, together with a Personal Computer (PC)
equipped with a good quality soundcard and SDR software.
The SDR software makes it possible to demodulate different modes, such as SSB, AM, FM and DRM.
The receiver is tested with several SDR programs. See chapter 4.2.
Figure 1-1 gives you an overview of the functional modules and the signal flow.
All modules are on the upper side of the board connected with RG174 SMB pigtail cables. The I2C signals
and power supply are put through via the 30-pins card edge connectors on the motherboard.
The interconnections between the modules are performed over the motherboard. There is no separate wiring
needed.
The receiver has a modular set up with a motherboard. There are 4 card modules, a LCD module behind the
front panel and an attenuator module behind the rear panel.
The receiver tuning is as desired manual by an encoder mounted on the front panel or via USB and suitable
software.
The RF front-end is based on the LT5517 I/Q demodulator of Linear Technology. This demodulator has a
high IP3 and a wide frequency range from 3.5 MHz through 440 MHz, applied in this receiver.
The receiver consists of the following 7 modules:
• Attenuator module
• HF band filter module
• VHF-UHF module
• I&Q demodulator module
• Synthesizer module
• LCD module
• Motherboard module
1.1 Attenuator module.
The incoming antenna signal on the BNC connector goes via the Attenuator to the HF- or VHF/UHF
module. The Attenuator has 4 states: 0 dB, -10 dB, -20 dB en –30 dB and these states can be selected by the
ATTEN push button on the front panel. The actual attenuation is displayed on the LCD.
Depending on the actual frequency, the microprocessor selects the right filter module for HF, VHF or UHF
use.
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Instruction manual KH-SDR wideband receiver Kit No-1021. All rights reserved KTH-SDR-KIT. Software design by PA0RWE.