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NARC invited members of the MKARS to the club to give a talk on their club project the MK80ARS. NARC bought over 25 kits and began the construction as a club project.

David G7URP produced a handy PDF to assist with the construction.

Brief Specifications
Frequency - whole 80M band by VFO     makrs80
Modulation - lower sideband SSB
Power output - >5W PEP into 50 Ohm load
Sensitivity - <1uV
Audio output - > 0.5W

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 has been made easier and more pleasurable by having when built in its simplest form a completely "wireless" design, though the extra options mentioned below 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.

Brief Specifications down Completed Project
bullet Frequency - whole 80M band by VFO makrs80
bullet Modulation - lower sideband SSB
bullet Power output - >5W PEP into 50 Ohm load
bullet Sensitivity - <1uV
bullet Audio output - > 0.5W
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:
bullet Use of a low cost "polyvaricon" type variable capacitor for the VFO and a large 10cm knob in lieu of a slow motion drive .
bullet 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.
bullet Standard discreet 10MHz crystals in the 4 pole IF filter.
bullet Single board construction without the need for inter-stage screening.
bullet Low cost IRF510 MOSFET transistor as the RF output device.
bullet 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. The price is £40 including the display and £45 including case, with a £5 discount for MKARS members. To keep costs down the latest printed construction manual and revision notes are available for download via the internet. It may be possible to supply paper copies for those without access to the internet but a charge will apply for this extra service.

Construction has been made easier and more pleasurable by having when built in its simplest form a completely "wireless" design, though the extra options mentioned below 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.