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Epiphyte MK IV
C&DARC are updating a much loved (and built) design by Derry Spittle. The Epiphyte is a compact QRP 80m transceiver, which has been tweaked and improved over the years from the original to the current MK III version. The MK IV is a substantial redesign aiming to remove most of the obsolete components, add some of the widely used modifications and generally try and perfect the design.
The journey is not yet complete – at the time of writing (March 2007) a working prototype has been built. We expect it to be available as a kit later this year. The first batch of kits are intended for C&DARC members, join us to be included! A second batch will be produced for for anyone else who wishes to build the MK IV, please contact us to register your interest, or for more details. Epiphyte MKIV
Epiphyte MK III and MK IV compared.
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Epiphyte Mk III |
Epiphyte Mk IV |
Band |
80m SSB transceiver 3.5-3.8MHz |
80m SSB transceiver 3.5-3.8MHz |
Tuning |
Standard VCO with 10 turn pot, prone to drift |
Microprocessor controlled VCO, zero drift, station buttons and rotary encoder control |
Display |
- [Note 1] |
Backlit LCD 2 line x 16 char display. Displays frequency, signal strength etc. |
S Meter |
- |
Signal strength shown on LCD display |
Front end filter |
LC tuned circuit 200KHz BW |
Band Pass Filter, full 300KHz BW |
Audio Amp |
LM386, no volume control (AGC design precludes it) [Note 2] |
5W high quality with volume control, ext. speaker & headphone outputs |
Audio filters |
- |
High pass + 2 Low Pass Speech + Phasing CW filter |
AGC |
Basic AGC, reduces RF gain on transmit as well as receive |
4 speed AGC operating on receive only |
Transmitter |
8W. Uses obsolete driver chip [Note 3] |
1W / 10W switchable |
CW TX |
- [Note 4] |
CW Key input, automatic transmit keying with 800Hz side tone. RS232 connection to computer for automated morse encoding and transmission |
CW RX |
- |
Phasing CW filter reduces ‘ringing’ compared with conventional narrow filters. Built in morse decoder to LCD display and RS232 connection to computer |
Construction |
Designed a single Double Sided PCB. No specified box or other components. |
Designed as a complete radio kit requiring just a 12V power source and 50W antenna. 2 Double Sided PCBs (Main board + Front control panel) Designed to fit a specific commercial enclosure, all components specified. |
Setup |
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Automated alignment procedure using microprocessor to aid setup of filters, oscillators etc. |
Notes (These apply to the MK III and earlier versions))
Frequency display kits are available from third parties
A rheostat can be put in the speaker lead as a rudimentary volume control
Chips can still be obtained from specialist suppliers at high prices (>£20 each)
A (fairly major) modification is available to add CW transmit support