User guide

ManualsBrandsElecraft ManualsAccessories communication2T-Gen

ELECRAFT 2T-gen 2-Tone TEST OSCILLATOR

Rev B, March 10, 2010

Introduction

The Elecraft 2T-gen is a 2-Tone test oscillator that can be used to make distortion measurements on SSB

transmitters and amplifiers. The 2T-gen is battery operated and provides sufficient output level to be

connected directly to the microphone connector of almost any transceiver.

Specifications

AF Output Level 200 mV max, adjustable, female RCA connector

Frequency 700 Hz and 1900 Hz

Harmonic Distortion -55 dB typical

Current Drain About 3mA from on-board 9-V battery

Size PC board: 3.5"L x 2.4"W; 1.0"H

Parts Inventory

R2,R6 (2) Res, 8.25 k 1% (gry, red, grn, brn, brn), E500176

R3,R9 (2) Res, 3.3k 5% (org,org,red), E500017

R5,R11 (2) Res, 1M 5% (brn,blk,grn), E500024

R4,R10 (2) Res, 100k 5% (brn,blk,yel), E500006

R1, R7 (2) Res, 6.8k 5% (blu,gray,red), E500115

R8,R12 (2) Res, 22.6k 1% ( red, red, blu, red, brn), E500175

R13, R14 (2) Res, 10 k 5% (brn, blk, org), E500015

R15,R16,R17,R18 (4) Res, 22K 5%, (red,red,org), E500090

R20 (1) Res., 47K 5% (yel,vio,org), E500067

C1, C3,C5,C7 (4) Mono Cap, 0.22uF (224), E530079

C2,C4,C6,C8 (4) Poly Cap, 0.01UF (103), E530009

C9, C10 (2) Electrolytic Cap, 22 µF E530143

D1 (1) Red LED, round, E570025

R19,R21 (2) 10k Pot, E520005

S1 (1) Miniature slide switch, E640009

JP1, JP2 (2) 3-pin header, E620053

J1 (1) RCA Connector, E620057

U1, U2 (2) LMC6842AIN, E600011

Q1,Q3 (2) Transistor, 2N3904, E580017

Q2,Q4 (2) Transistor, 2N7000, E580002

(1) 2T-gen Printed Circuit Board, E100256

(4) Self-adhesive mounting feet, E700024

(2) 2-pin jumper block, E620055

(2) 4-40x5/16 machine screws, E700077

(2) #4 internal tooth lockwashers, E700010

(2) 4-40 machine nuts, E700011

(1) Battery Holder, E980074

Summary of content (8 pages)

PAGE 1
E L E C R A F T 2T-gen 2-Tone TEST OSCILLATOR Rev B, March 10, 2010 Introduction The Elecraft 2T-gen is a 2-Tone test oscillator that can be used to make distortion measurements on SSB transmitters and amplifiers. The 2T-gen is battery operated and provides sufficient output level to be connected directly to the microphone connector of almost any transceiver.
PAGE 2
Assembly  Sort the resistors by value. Some of the color bands may be hard to read; use a magnifying glass if necessary. A Digital Multimeter (DMM) should be used to confirm the values.  Orient the printed circuit board with the silk-screened side up and the title “2T-gen” at the upper left.  Install the following resistors in their indicated positions, starting at the top of the PC board and working down and right. (Complete the left column, below, then the right column.
PAGE 3
Initial Test  Set S1 (small slide switch) to the OFF position.  Install a 9V battery into its holder.  Connect the output of the 2T-gen to the input of a sound system or to headphones using a suitable adapter cable.  Set R19 and R21 to about mid-range.  Turn on the 2T-gen. The round red LED will light.  The 2T-gen output should be heard on the sound system or headphones.
PAGE 4
which results in a 3rd order product of 3100 Hz and a 5th order product of 4300 Hz. The amplitude of these undesired outputs is usually increased as the transmitter output is increased, and is caused by various transmitter amplifier stages beginning to operate in compression. A properly operating transmitter should produce third-order IMD products that are 27 to 30 dB or more below the PEP output power. The PEP output power is 6 dB higher than the output power produced by the 700 Hz and 1900 Hz tones.
PAGE 5
In recent years, a much more convenient measuring device has become available at reasonable prices. A used spectrum analyzer can be purchased at flea markets and used test equipment dealers for very reasonable prices. Several PC-based spectrum analyzers have been designed and published also.
PAGE 6
PAGE 7
Schematic 7
PAGE 8