Hello Julian,
I also noticed the other day that I was hearing a whoosing in the background
on
a CW station that I never heard before. I was afraid I had blown a preamp or
something. I finally found that I had set the NB on Wide 7, and as soon as I
turned it off or back to Nar 1, the problem disappeared.
So something must have changed in the NB operation in the latest Firmware. I
also
found last weekend when I switched to 144 MHz in the transverter mode for an
EME
sked, that my audio output from the LINE OUT suddenly seemed to be 15 or 20 dB
down on that band, as compared to 6m. That had never been a problem before. I
don't know if that is also related to the Firmware version or not.
In the last week I also found that the noise level seemed to come up higher and
reduce signal strength of incoming signals I use as reference (6m beacons).
Anyway, I still use the same firmware version, but I re-loaded a Configuration
file that I had saved several months ago...and readjusted the LINE OUT level in
the CONFIG menu. That seems to have solved the problems except the one with
the
NB. Now I have to be very careful not to use the Wide 7 NB setting.
GL and VY 73, Lance
On 2/6/2010 2:33 AM, vk4cmv wrote:
The other day I was receiving a very loud (S9+10) Jt65a signal from a local
station and was noticing that his signal seemed to be modulated by a
commercial radio station. So I was just about to send him an email saying
that he had a problem, when I adjusted the RF gain, turned the ATT on and
turned the PRE off. His signal was now sweet.
So I switched to another sound card - and still the same result after I had
reset the controls again.
Then I remembered that I had set the NB on (dsp off) and IF to Wide 7 and
as soon as I had turned the NB off, his signal was copied just fine. What I
found was that setting the IF to Wide 7, Med 7 or Nar 7 gave rise to what
only can be described as intermodulation.
The reason I use the NB at all is because my neighbour has one of these
solar pads that heats his swimming pool on his roof, and the pumps in it
generate this ta-pocketa-pocketa-pocketa noise (like an electric fence, but
faster) - and I just leave the NB one most of the time, because my
neighbours also own behemoth plasma TV sets :)
So two questions:
1) has anyone else noticed spurious intermodulation in DATA mode when the
IF NB is set to the 7 level - or have I got a fault?, and
2) Is there a beginner's guide to help me understand how to use the NB
effectively - at the moment, I just spin the dials until the noise is gone.
thanks, Julian VK4CMV
--
Lance Collister, W7GJ (ex: WN3GPL, WA3GPL, WA1JXN, WA1JXN/C6A, ZF2OC/ZF8,
E51SIX)
P.O. Box 73
Frenchtown, MT 59834 USA
QTH: DN27UB
TEL: (406) 626-5728 URL: http://www.bigskyspaces.com/w7gj
LIVE MESSENGER CHAT: w...@hotmail.com
2m DXCC #11, 6m DXCC #815
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