Hi Allen,
Sounds like a really nice rig. Good that you have described what
filters are in it. Your description is a bit off, as far as the way you
have labeled the orders of the IFs.
In an Omni VI, the first conversion from the antenna signal to an
IF, is to the 9 MHz IF. This is where all of the 9 MHz crystal filters
are, and it is the First IF. The next conversion is to the 6.3 MHz IF,
which is shifted by the Passband Tuning (PBT) control. The 6.3 MHz IF is
the Second IF. After the 6.3 MHz PBT IF, the signal is converted back to
9 MHz and goes to the product detector, where it is mixed with the BFO.
You could say that the 9 MHz signal coming out of the PBT board, going
to the product detector is a Third IF. Or maybe you could call it the
"Second 9 MHz IF". There are no crystal filters here though, so all of
the 9 MHz crystal filters are truly in the First IF.
There is another IF that can be called a Second IF, since it is
after two frequency conversions. That is the 455 kHz IF used in the FM
detector. This other second IF is only used when in FM mode.
If you count the very first crystal filter, the two pole 15 kHz wide
one before the noise blanker, as the "First IF Crystal Filter", you
could call the default stock 48058 filter the "Second Crystal Filter"
and the "nar1" and "nar2" filters could be called the "Third crystal
filters", however they are in the "First IF" after the first frequency
conversion and before a second frequency conversion.
I know that I am being picky, but what the heck, I am correct about
this.
Hope you do not regret selling your Omni VI. It is a great rig.
DE N6KB
If
Configured with available TenTec only filters:
Bandwidth (Hz) 2400 1800 500 250
Mode SSB SSB CW CW
2nd IF /9000 (3 slots) 48058**
218
(nar 1) 217
(nar 2)
3rd IF/6300 (4 slots) 48074** 288 285 282
** OmniVI stock 2400 8 pole filters
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