Dave,
You might want to review the method used by the ARRL for their
blocking and IMD testing. For these tests they use an extremely narrow
bandwidth, maybe as narrow as 10 or 20 Hz. Completely unrealistic for
any normal use.
What you want to look at is the *lower* of BDR/IMD *or* 'reciprocal
mixing dynamic range'. For the K3 the RMDR is much lower than IMD/BDR.
You might also want to check Sherwood Engineering's site. His
'receiver test data'. He does not use such unrealistic test methods.
The K3 is still better than the Pro3 but not as much as ARRL numbers
indicate.
And note that what you are seeing is likely TX phase noise from the
other transmitters. There is nothing you can do about that. The TX has
to clean up their act.
73 de dave
ab9ca/4
On 4/5/14 11:51 AM, David Cole wrote:
Hi Dave (K6LL),
Thanks for that thought, but I am pretty sure it is not their rigs...
Here is my reasoning for why I think that:
One rig is a K3, and an AL-1500, about 1/2 mile from me, and line of
sight. One of the the others is a 756 PRO III, and I don't know what
amp, about a half mile from me, while the third is an older Collins rig,
with an older Henry amp, about 100 yards from me.
All three rigs, and my mobile rig in the driveway, cause exactly the
same effect when they are transmitting, the band scope, (set to
something like 200 KC wide), shows perfectly straight increase across
the entire 200 KC's of scope, along the bottom, as a raised noise floor
would. It looks like phase noise, but I would expect that to roll off,
and not be as flat as this is. I also live close to an AM station,
100KW, and about a mile and a half away, and I see almost the same
thing, as I approach the station frequency. I can see the entire noise
floor raise as I get closer to the station.
I have an inrad roofing filter installed to the PRO III. Does this
still sound like Phase Noise to you?
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