LD-1TR Software-Defined Transmitter

Turn your LD-1B2 receiver into an LD-1TR 5-Watt (nominal) HF / MF transciever for only $125 by installing the NEW LD-1TX software-defined transmitter module. Also compatible with the LD-1B receiver, the LD-1TX is designed for easy, fast installation with no tools except a Phillips screwdriver.

Here's a video demonstrating the LD-1B with Winrad 1.6.1 software. The antenna was an MFJ Super Hi-Q Loop, and the soundcard was an E-Mu 0202. To order an LD-1B, go to the Lazy Dog Store.

	LD-1TX Hardware: The LD-1TX hardware includes a DDS I/Q local oscillator, quadrature sampling modulator (QSM), push-pull power amplifier, and a set of six, relay-switched lowpass filters. It works like the LD-1B2 receiver, but in reverse. Modes include AM, FM, CW and SSB. Most digital modes can also be used, through third-party software.(Back to Top)
	Host Software: The host's SDR software, which is available from several third-parties at no cost, performs IF signal processing and demodulation. Compatible modes include AM, FM, SSB, CW, and in some cases DRM. "Soundcard" modes such as PSK31 are available using appropriate software and a second soundcard or Virtual Audio Cable. HDSDR (similar to Winrad) is preferred, because of its transmitter support features and because the LD-1TR software installation package includes a DLL which connects it with HDSDR's controls so the operator can change the LO frequency either from Winrad or from the LD-1 control panel. A standalone LD-1TR control application is also included in the installation package to let you use your LD-1TR with other SDR software, such as Rocky. (Back to Top)
USB-Controlled Frequency-Agility: The SDR software has a tuning range of 48 kHz, 96 kHz or 192 kHz, depending on the soundcard's sample rate. The tuning range is centered at the LO frequency, so the crystal-controlled LO found in many low-cost SDR's restricts the frequency coverage to a single 96-kHz range. The LD-1TX uses a synchronized pair of direct digital synthesizer (DDS) chips as its quadrature LO, resulting in extreme frequency agility. The LO frequency is selected via a USB connection, either from the LD-1TR's control panel (shown above) or directly from HDSDR. When the LO frequency is changed, one of the eight receiver preselector filters and one ofe the six transmitter lowpass filters are automatically selected. These control functions are performed by a microcontroller. The microcontroller's firmware may be updated by the user via the USB cable. (Back to Top)
Soundcard Considerations: Like any SDR which relys on a host computer and soundcard, the LD-1TR's performance is dependent on the performance of the soundcard. An expensive professional-grade soundcard like the Delta-44 is NOT required. The LD-1B performs very well with a Creative SB1090 USB sound adapter, which is available for $50 - $75 dollars and is ideal for portable use with a notebook PC. For transceive operation, two soundcards are required. The PC's internal soundcard can be used as one of them, for mic input ans speaker or headphone output, with no performance degradation. The other, which should be of reasonably high-quality (SB-1090, SB-1095, E-Mu 0202 or similar) is used as an interface between the LD-1TR and the PC. (Back to Top)
Performance: The LD-1TX's performance has not been fully characterized, but the power output is 5 Watts or more from 160 meters to 20 meters, and slightly less above 20 meters. (Back to Top)
Professionally Designed For Amateurs: The LD-1B was designed by a lifelong ham with degrees in Electrical Engineering from Rose-Hulman Institute of Technology and Purdue University, and 30+ years of industrial and academic experience, so you can rely on its technical soundness. It is built on a high-quality PC board using dedicated power and ground planes as well as extensive decoupling to minimize EMI and EMC problems. (Back to Top)

LD-1TR Specifications
Frequency Coverage:	100 kHz - 30 MHz (transmit on amateur bands only
Sensitivity:	0.18 µV for 10 dB signal-to-noise ratio at 10 MHz
Image rejection:	Comparable to Amateur-grade receivers
Overload Characteristics:	Comparable to Amateur-grade receivers
Power Supply:	13.8VDC "wall-wart" with 2.1 mm x 5.5 mm male connector, available seperately
Rear Panel:	3.5 mm stereo output jack, 3.5 mm stereo input jack (for planned transmitter module when available), 3.5 mm "stereo" accessory jack, USB mini-B for connection to host, SMA female antenna connector, and 2.1 mm x 5.5 mm coaxial female power connector (center positive).
Front Panel:	Power switch (push-on, push off), green LED power indicator, red LED mute / transmit indicator
Dimensions:	1.1875 x 3.125 x 7.0 HWD (overall)