[Elecraft] Elecraft XG1 Receiver Test Oscillator/S-Meter Calibrator

[Wayne Burdick]

Ever wonder how well an HF receiver is really working--or how one receiver
compares to another? One of the most important performance measurements is
sensitivity. But measuring sensitivity (MDS or signal-to-noise ratio) usually
requires an expensive, lab-grade signal generator. 

At just $39, our new XG1 Receiver Test Oscillator is an inexpensive alternative.
The XG1 is a fixed-frequency (7.040 MHz) signal source with highly-accurate 1
microvolt and 50 microvolt output levels. Thanks to its precision, low-level
crystal oscillator, the XG1 achieves absolute output accuracy of better than +/-
2 dB, and extremely small unit-to-unit variation of typically +/- 1 dB. This
ensures that measurements made with different XG1s can be compared, which can be
helpful when evaluating used equipment found at flea markets or on the web.

The 1-microvolt level can be used to determine a receiver's MDS (minimum
discernable signal), as well as its overall receive gain. 50 microvolts is
widely used as the standard "S9" reference, so this level can be used for
S-meter calibration. Step-by-step procedures are included for receiver
performance measurement and S-meter alignment.

Additional features of the XG1 include an on-board 3-volt battery (standard coin
cell), low-battery LED (yellow), power-on LED (green), and reverse-transmit
warning LED (red). The unit is protected against brief accidental transmit, and
has been tested at up to 10 watts for 2 seconds. But the provided test
procedures include warnings about disconnecting the key, mic, etc., so
accidental transmit into the XG1 is unlikely.

An output frequency of 7040 kHz was selected because nearly all multi-band HF
transceivers, as well as many monoband transceivers, cover the 40 meter CW band.
But the XG1 also provides reduced output levels at harmonics of 7040 kHz, so it
can be used for receiver alignment and qualitative tests on 20, 15, and 10
meters. 

Since the oscillator itself puts only 10 nanowatts, the unit requires no
enclosure and no interstage shielding. Careful PC board layout and component
selection ensure that RF leakage is virtually eliminated. Assembly takes only
about an hour, and the only alignment step--which is optional--is fine-tuning
the frequency of the crystal oscillator while listening on a calibrated receiver.

The XG1 is the fourth in our series of easy-to-build mini-module kits, which can
be seen at: 

   http://www.elecraft.com/elecraft_prod_list.htm

Like our other mini-modules, the XG1 is quite small: the PC board is just 1.5"W
by 3.5"L. You can use a BNC male-to-male adapter such as our #BNC-MM to
eliminate the coax cable and directly connect the XG1 to the back of a receiver
or transceiver. Stick-on rubber feet are also included so the unit can be used
on your work bench.

The XG1 will begin shipping on or before December 12th.

73,
Wayne, N6KR
Eric, WA6HHQ

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http://www.elecraft.com