[Elecraft] XG3 Signal Generator

[Don Wilhelm]

Greg,

The XG3 is a fine and easy to use tool.  It is useful for a lot more 
than just calibrating the S-meter.  When used with the XG3 Utility, it 
can serve as a full function signal generator with sweep capability.

Yes, the output is a square wave, but as soon as the signal is fed into 
a receiver, the filters turn it into a sine wave.

The only limitation of the XG3 is that it cannot do extremely low levels 
because the plastic case has some low level leakage - even a step 
attenuator is not effective at extremely low levels unless the XG3 is 
put inside a metal enclosure.  I pressed my old HP8640 into service for 
any low level testing (like MDS testing).  My mil-spec HP8640 would go 
down to -140dBm without leakage because it had all the internal shield 
boxes with all screws intact.

73,
Don W3FPR

On 3/24/2020 3:41 PM, Greg Troxel wrote:
> Bill Smith via Elecraft <elecraft at mailman.qth.net> writes:
> 
>> Looking at buying the XG3 signal generator to calibrate S meters.
>> Particularly thought it would be very useful to calibrate the S meter
>> in the HDSDR SDR software I use now.  I read the S meter calibration
>> instructions in the manual and was happy to see how simple it is.  If
>> I had tried to use my old Tektronix signal generator I would of had to
>> buy an RF Power meter to measure the amplitude and a Step Attenuator
>> to adjust for -73db/50uv.
> 
> No, but I intend to do this.  It's certainly simple on the XG3 side; the
> possibly hard part is on your receiver's side.
> 
> Beware that the XG3 output is a square wave.  I am 99% sure that this
> means the stated power of e.g. -73 dBm is the power of the desired
> frequency, and the power of the third harmonic is not included in that.
> Certainly that is what you'd want for receiver testing as a ham receiver
> should be expected to not respond to the third (fifth, etc.) harmonic.
>