I picked up a P3 kit last week, put it together for FD.
Took it up to Bonny Doon and had it in our CW station.
We (several operators) observed a strange behavior.
With the bandspread opened to 200kHz, and with noise floor ~ -130dB, there
seemed to be a "broad hump of noise" on the upper half side of the display,
about 80kHz wide. This "hump" started about mid-scale (center freq),
gradually rose to +20 dB above the noise floor, showed some rise/fall/rise
structure (in its smoothed display), and then fell back down to the floor
about +80kHz beyond mid-scale.
When we varied the VFO, the "hump" stayed in same relative position on the
display, and its structure remained the same.
Seems it is some type of artifact, or leakage or ?
When I got it back to QTH, I looked across different bands, each having
slightly different noise levels. The peak amplitude of the "hump" stayed
the same, independent of the band floor itself.
When I switched between USB/LSB, the structure of the "hump" changed
slightly --- the up/down of its amplitude seemed to shift in phase by ~180
??.
Lastly, when I switched to 6m band, the "hump" shifted to the opposite side
of the display. In this, it still retained the same shape.
This seems to be some type of artifact, and it shows itself in all the
display modes (averaged, waterfall, etc.)
Physical arrangement of gear:
K3 powered by linear supply.
K3 grounded to mains ground.
K3 through Viking 1kW matchbox to ladder-line doublet.
K3-P3 links as-per-document
supplied 12v link
supplied mini-coax link
supplied db25 command link
Any ideas out there on what might be happening here ?
--
thanks and 73
Tom Kenville -- W6TJK
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
