VRX-1 Versatile Receiver
Designer's Radio Bio
This Kit Has Been Retired
VRX-1 Versatile Receiver
By Jason Mildrum, NT7S
Click for larger image
Another Great Manhattan Kit Offered By The Four State QRP Group
The VRX-1 is a simple yet versatile direct conversion
receiver that employs some circuitry not commonly
seen in the QRP kits currently on the market. The kit is
shipped to be built as a VXO-tuned 40 meter receiver,
although it can be reconfigured for different bands and
types of tuning with a few parts from the junkbox. The
simplicity of the design lends itself to easy modification
and experimentation. This kit is an inexpensive, solid performing direct conversion
receiver that can be built for any of the 9 HF bands, 160M through 10M meters.
This is a good kit for first time Manhattan builders.
The designer's excellent instructions and pad template combine to make this a successful first Manhattan project.
Specifications and Design Features ... There are no surface mount parts in this kit, it uses all through hole components. Direct Conversion topology, Tuning Range: Approximately 7.028 to 7.032, Current Draw: ~40 mA at full volume.
The audio stage is NOT the ubuiquitous LM386 normally found in inexpensive receivers and audio amps. The VRX-1 employs the superior 1 watt TDA7052 audio amp as it's output stage,
This IC is quieter than the LM386, has nearly as much gain, and with it's excellent fidelity, it plays extremely well into a set of headphones. Other noteworthy features are:
no switch-on or switch-off clicks, good overall stability, no heat sink required, and it's short-circuit proof. So it's a very user friendly chip.
Documentation... The assembly instructions are here
The documentation includes excellent written instructions, many photographs and
diagrams, and can be easily built from the pictures and parts layout template. Of special interest are the circuit descriptions in each section. These describe the function of each section as you build the receiver.
Making the documentation a fine learning experience in addition to a Manhattan construction tutorial.
Click here for some building notes from Jason.
The schematic is here.
Uses ... This simple but useful receiver is intended
to be an entry level receiver which will provide a good Manhattan building experience. It can be employed as either a stand alone receiver or used in conjunction with a separate transmitter. An external antenna T/R switch is needed for operation with a transmitter.
It is capable of many QSO's and some have already been made with the beta prototypes. Although it comes with parts for 40M, It can be
easily modified for any of the HF ham bands, with parts that you supply. Component values and modification instructions are included for each band of interest. See page 15 in Jason's instructions.
The Kit Includes ... All components, documentation, prepared copper clad board, and associated parts to build the receiver complete, less connectors, coax,and enclosure.
Special thanks to Expanded Spectrum Systems for their fine support of the Four State QRP Group.