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Minimum carrier detect level
-140 dBm is that good ?
Run into a odd problem on 500Khz
, neither the RA6790 (with LF front end / no rf pre amp)
or the RA1778 will show a carrier on 504 Khz ,
that the Skanti R5003 , shows at 10/20 dB over the noise
level using 'spec-lab' as the indicator, R5003 , has no
pre-amp , direct to first mixer. same as the RA
6790
Using the sig-gen and 60 dB
atten , the RA1778 minimum trace level is -150 / -155
dBm (has rf-pre amp) , The 6790, round -140 / -145.. removing
the rf cable and fitting 50 ohm load to gen
o/p with atten , removes the trace from the rx, so
assume its not leakage
As these levels are well
below the ambient noise levels, it not a
sensitivity problem .??. adding a stepped attenuator to
the Ae signal path , makes no difference, other
than to alter the noise level..
The 500 khz feed is from
the atu and the vswr round 1:1.2 on tx .The R5003
is the same lay-out , 40 meg 1st IF > 1.4 second (rx
section of the TRP5000)
Any ideas or suggestions as
to 'how' to solve the problem ..
wide band noise causing the
roofing filter to ring may be?
Tnx -Graham
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