Sounds like they rely on the filter to eliminate the carrier as much as the
null adjustments. Or that the filter's input impedance is critical to the
carrier's null (unlikely). Either way, it from what you have said the
filter is drifting (temperature) somewhat causing the skirts to drift a
bit causing there to more carrier at times than others. And the TT filters
are stable and perhaps even have a notch at the carrier frequency. Just a
guess I have not had any direct experience.
73
Bill wa4lav
At 08:02 AM 11/20/2003 -0500, you wrote:
I installed the INRAD 9MZz & 6MHz filters (754 &755) in my Omni VI
+ about two years ago. They performed well.
Recently some one complained that I had carrier on my sig.
When I put the Omni V! on my spectrum Analyzer (IFR 1200S), I noticed a
substantial amount of carrier (abt 12W) After adjusting R3 & R4 on TX
Audio Board I was able to null carrier.
However, there still seemed to be a higher than normal residual carrier
(appx 50 mw).
When the Omni VI was connected to my amplifier, I could measure appx 1.5
to 2 W of carrier on USB & .5 to 1 W on LSB. In addition, these reading
were unstable.
When I switch from the tune posirion to USB or LSB I measure 4-5 watts of
residual carrier which gradually decreases to 1 - 2 watts.
When the rig is turned on from a "cold start" with the amp in line I
measure 10 -0 12 watts of carrier which gradually decreases to app 4 W.
When I install the original TT 9 MHz filter in the Omni, all the stated
problems "go away."
TT thinks there is a problem w/INRAD filter & George from INRAD thinks
that there is a problem w/ the Omni VI +.
Again, Omni works fine w/original TT 9 Mhz filter
Does any one have any ideas or comments.
TNX..Joel W4SLH
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