Elecraft 2T-Gen - Manual (Page 3)

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.

Place the jumper block over the “NT” pins or JP1 and JP2 in turn and confirm that only a single tone is
heard when the jumper block is in place.

Return the jumper blocks to the “T” position.

This completes the initial test. Turn off the 2T-gen to conserve the battery
Using the 2T-gen
Controls and indicator LEDs
 Power-on LED (red): Turns on when the 2T-gen is in use.
 Output Level Adjust: Allows adjustment of the output level to the desired level.
 Balance: Allows adjustment of the two tones to produce equal transmitter output power.
 JP1 and JP2: Provide control of the oscillators. Placing a jumper block over the “NT” pins will turn off
the associated oscillator. Placing a jumper block over the “T” pins, or removing it entirely, will turn on
the associated oscillator. JP1 controls the 700 Hz oscillator and JP2 controls the 1900 Hz oscillator.
Applications
The 2T-gen has been designed to provide a 2-tone signal source for testing of SSB transceivers and
associated amplifiers. This type of testing is almost universally used as a measure of transmitter linearity for
amateur radio equipment. Results of 2-tone IMD tests can be found in every ARRL review of new
transceivers and power amplifiers.
When connected to the 2T-gen, the ideal SSB transmitter will produce an output that consists of only two
frequencies, for USB these will be the carrier frequency plus 700 Hz and the carrier frequency plus 1900 Hz
and for LSB the frequencies will be carrier minus 700 Hz and carrier minus 1900 Hz.
Actual transmitters will produce spurious output at additional frequencies as a result of nonlinearity. The
highest amplitude spurious output will normally be the third-order product and the next highest will be the
5th
order product. Higher-order products may also be present at lower amplitudes. These spurious products
are referred to as the intermodulation distortion (IMD) products.
The 3rd
order product will appear at a frequency offset from the carrier by 2F
2
–F
1
and the 5th order product
will be offset from the carrier frequency by 3xF2-2xF1. For the 2T-gen, F1 is 700 Hz and F2 is 1900 Hz,