
revised 3 Feb 2021 Bayou Jumper revB Assembly Manual page 2 of 46
The entire transceiver was designed to fit inside a standard wooden box,
available from Hobby Lobby. It can be ordered here:
http://www.hobbylobby.com/Crafts-Hobbies/Wood-Crafting/Unfinished-Wood/Wood-
Rectangle-Box-Set-with-Silver-Handle/p/25426-GA0369
The on-line sale is for a set of three boxes, of which the smallest is used. The
boxes can be purchased individually in stores, SKU# 662536S.
Theory of Operation
The Bayou Jumper, like the Paraset that inspired its creation, utilizes very
simple and robust circuitry to achieve reliable operation. Despite this simplicity,
it attains the maximum of performance from its minimum number of
components, in the true spirit of QRP.
The transmitter design of the Bayou Jumper is borrowed from the 4SQRP
classic ‘NS-40’. This design is a master-oscillator/power amplifier circuit, with
high-efficiency spiral PCB coils serving as the transmitter’s harmonic filter. The
2N7000 Master Oscillator, Q5, works against the gate capacitance of the
IRF510 power amplifier, Q4, as an unusual inverted Colpitts oscillator. The
power amplifier Q4 is tuned to operate in the Class E mode, generating 5 watts
from 13.6 volts, at better than 85% efficiency. Closing the key contact grounds
the source circuits of Q4 and Q5 permitting oscillation to commence. If the
transmit/receive switch is in the receive position, closing the key permits the
Master Oscillator to oscillate without the PA operating, enabling spotting of the
oscillator frequency in the receiver.
A built-in key is included in the design –just like in the original Paraset!
Because the entire PA current passes through the keying circuit, it is
recommended, for those who want an external key, that the transmitter be
keyed through a hard contact closure, like a relay or straight key, or that a husky
MOSFET (IRF510 or larger) be used. See APPENDIX J for suggested circuits.
The receiver is a simple regenerative circuit, based on the innovative designs of
Charles Kitchin, N1TEV. Q2, an MPF102 JFET, is a regenerative detector in an
Armstrong circuit, with a 1N5819 diode acting as a varactor capacitor in the
tickler throttle circuit. The regeneration control, potentiometer R10, varies the
reverse bias voltage on the diode D2, changing its capacitance and varying the
amount of feedback current it passes through the tickler feedback winding of L1.