The Corsair II was equipped bare-stock with two 8-pole 2.4KHz filters:
One in the 9MHz 1st IF (on the 81252 XTAL FILTER board), and
One in the 6.3MHz 2nd IF (on the 80979 PBT board).
The 9MHz cf 2.4KHZ 1st IF filter could be considered a "roofing filter", and is
in-circuit full time...dictating both RX and TX passband width.
The four 6.3MHz cf 2nd IF filters (including the three optional filters)
dictate only the RX passband width, and are installed on the 6.3MHz 2nd IF
80979 PBT board.
Which one of the four 2nd IF filters is selected, is dictated by a combination
of the "MODE" and "XTAL" switches.
With all three optional filters installed:
SSB mode: XTAL 3=2.4KHz PB; XTAL 2=1.8KHz PB; XTAL 1=500Hz PB.
CW mode: XTAL 3=1.8KHz PB; XTAL 2=500Hz PB; XTAL 1=250Hz PB.
BTW, the 81252 XTAL FILTER board is mounted on a vertical chassis (cavity) wall
at the rear of the 80979 PBT board, which is not ballooned/identified in the
manual's "top view" picture.
I just realized that some of this info duplicates that already provided by
Bill, W1PA. Sorry about that, but perhaps the additional info is useful.
73,
Allen--W7GIF
----- Original Message -----
From: Stuart Rohre<mailto:rohre@arlut.utexas.edu>
To: Discussion of Ten-Tec Equipment<mailto:tentec@contesting.com>
Sent: Wednesday, December 09, 2015 1:23 PM
Subject: Re: [TenTec] Corsair II - Filter Classtime Please
Most likely the 2.4 kHz filter is what today would be called a roofing
filter, and is in front of the switch, so it is always in the circuit.
Hence, 3 selectivity positions, each more narrow than 2.4 KHz.
Stuart Rohre
K5KVH
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