After lugging my HP8640 up the stairs again last night (ugh) to act as a
source for doing some feedline loss measurements I thought again about
getting an XG3 for this purpose. I have an XG2 but its max output is only
-73dBm. I downloaded the manual and looked at it and the schematics and
realized there is no output filtering rather a square wave is emitted.
So if used with a broadband power meter (like the PIC Power Meter) the PPM
would receive not just the fundamental but the whole spectrum emitted by
So if used for loss measurements it would seem that a short bit of cable
might allow the harmonics to contribute meaningfully to the received power
yet a long cable would attenuate the higher harmonics to a greater degree
and give an incorrect impression of the loss at say 7Mhz. Seems like this
device is only useful then with a tuned receiving device.
Just realized that the K3 internal voltmeter might be of use since it is
obviously frequency selective. I could put the XG3 (or better yet, the
already owned XG2) at the far end of the line after calibrating it in the
shack against the K3 then measure the signal on the K3 display and the line
loss would be the difference of the two.