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MKARS80

The MKARS80 transceiver, is available from www.radio-kits.co.uk and not from MKARS or this website directly. Please note that the details might be out of date. Please refer to www.radio-kits.co.uk for up to date details and prices.

Significant interest has been shown in the construction of Pic-A-Star transceivers (see Pic-A-Star pages) by members of MKARS, but for most the Pic-A-Star is either too complex or too expensive project to take on. The MKARS 80 was designed for those who would like to build and use the radio they constructed themselves; in the design of this radio I have tried to balance complexity, functionality and cost - most of all the radio must be usable.

Pictures of the first prototype and components for 25 kits

  

Prototype (track side)	Prototype (component side)
Brief Specifications Frequency: VFO complete 80m Modulation: LSB Power: >5W PEP into 50Ω load Sensitivity: <1μV Audio Output: >0.5W	Completed Project

Basic Description

The transceiver is based on a super-hetrodyne architecture using an IF frequency of approximately 10MHz. The circuit is developed from the BITX20 designed by Asshar Farhan, however significant changes had to be made to achieve the required performance on 80m.

To meet the cost target the radio has various "novel" features, these include:

• Use of a low cost "polyvaricon" type variable capacitor for the VFO and a large 10cm knob in lieu of a slow motion drive.
• Frequency lock circuit - this is internal and consists of a PIC micro which measures the VFO frequency and compensates for moderate drift, frequency range is approximately 1.5kHz which is sufficient to keep the radio on tune indefinitely if operating conditions (temperature etc.) remain stable.
• Standard discreet 10MHz crystals in the 4 pole IF filter.
• Single board construction without the need for inter-stage screening.
• Low cost IRF510 MOSFET transistor as the RF output device.
• Reverse polarity protection.

Construction

The kit of parts contains the PCB, the display and all components to be mounted on it, not included are case, knobs etc.

Construction has been made easier and more pleasurable by having when built in its simplest form a completely "wireless" design, though the extra options, such as an internal speaker, will require a small amount of wiring as will an on / off switch if thought necessary.

Full support will be given to any club member building the transceiver; as most problems can be traced to poor soldering and wrongly identified components a short lesson on correct soldering techniques and component identification will no doubt be provided before construction commences.

Introduction the MKARS80 at the Club

 

The standard kit comes complete with frequency display module. If this feature is not required the display and associated components can be removed from the kit and price adjusted accordingly.

More Information

You can purchase the MKARS80 kit and obtain templates and overlays from www.radio-kits.co.uk.

Or email Steve (G6ALU): steve123@radio-kits.co.uk

MKARS80 Yahoo group, useful information source:
http://uk.groups.yahoo.com/group/mkars80/