FT1000MP Noise Blanker - Settings
Don't know how many of the FT1000MP owners in CTDXCC also subscribe
to that reflector. Anyway, there's been a very interesting discussion
re the Noise Blanker. It is claimed that the NB pot is active in the
system, and can degrade performance, even when both NBs are switched
off!! Clearest statement on the matter came from Tim K3LR:
The problem with the NB front panel control is well documented by INRAD
in their "MP Filter Selection and Operating Thoughts" It is a 4 page
document. The document comes when you purchase INRAD filters.
The IMD is deteriorated when the NB1 and NB2 switches are in the OFF
position and the NB pot is in anything but the full CCW position.
I have received many emails telling me that operators do not see any
difference when he front panel control is varied with the NB's in the
OFF position. Not every receiver will be affected the same. Signal
strength and the number off signals on a band have a direct impact on
this problem. The only time I can hear the problem is when the bands are
full of contest signals...It is then very noticeable,
According to INRAD's excellent info, the third order intercept goes from
+14.5 dBm at full CCW to -7.0 dBm at full CW. This test was made on 7MHz,
tuned front end, 500/400 Hz CW filters. The difference is amazing (21 dB!).
The mod I mentioned before takes the NB circuit out of line when the NB's
are off and then the control has no affect on the receiver performance.
So if you don't make the mod, keep the NB pot fully CCW when not using the NBs!
73, John, NT5C.
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