the flea, 

a 40m minimalist transceiver


by Joan Morros, EA3FXF

and Eduardo Alonso, EA3GHS

6/mar/2009

 

 introduction

The transmitter is based in the old " Cubic Incher" by AE6C (QST, July 1982), verified in ARRL laboratories by Greg Bonaguide (WA1VUG). It runs very well. The receiver is really a new idea. My friend Eduardo (EA3GHS) and me are very surprised of his performance:

a) bias stability is not critical. It does not need adjustments. (the oscillator runs without bias!)
b) Sensibility: better than 0.7 uV (approx S2)
c) Crystal selectivity
d) Crystal stability in RX and TX
e) Full-break cw operation
f) Rx clarifier (+/- 500 Hertz.) (changing de bias point of the transistor)
g) One audio transistor amplifier is sufficient to attack a pair of 500 Ohm earpieces
h) conectable to soundcard of your PC to do digital filtering

* Get here the FLEA transceiver description from the SPRAT magazine.

* Get here the FLEA transceiver description in Chinesse (价廉物美)

* Get here the FLEA (Puça) transceiver description en Català  (translated by EA3DHC)

* Le Transceiver Pulga (le pouce en français) (translated by ON5FM) NEW

constructional note

Stephen VE7NSD has arrised about the correct winding of the FLEA coil.  This image try to resolve this question. The transformer do not modify the feedback phase. Read the comments of "dot-convention" here.


resources

Discuss about FLEA TRANSCEIVER in our mailing list (spanish) or EMFRD (english)

Get here the SPICE FLEA FILES or view pulga waveforms online

Get here the PCB FLEA FILES

 

 

View an advance of our next projects with PULGA

SUPERPULGODYNO: a superhetereodyne transceiver for 20 meters band NEW

PULGON40: a triode based PULGA

 Read more about others simple transceivers

  1. curumim by PY2OHH
  2.  a simple fet transceiver by designed by W2UW
  3. a simple triode transceiver
  4. WB3ELL one MOSFET transceiver
  5. GNAT40 from Arizona NEW 
  6. VS6CQ tube transceiver (Shortwave Magazine Set 1955 and RSGB Handbook)