[TenTec] Omni VI roofing filter JPG

[Chuck Guenther]

"Is there any compensation for the insertion loss of the filter?"

Yes, the filter board includes a transistor amplifier; however the roofing filter is only a four-pole configuration (and fairly wide bandwidth (600 Hz for CW) so there isn't much loss to begin with.  When I turn on my NAR switch which engages both the roofing filter and the INRAD 753 (which has a nominal insertion loss of 9 dB), I see the s-meter go down about 1.5 "s" units.

"Surely it works in parallel with whatever filter is in N1 or N2 and doesn't
waste a slot.  And if you want it always on, a simple diode should do the
trick."

The roofing filter operates on the signal input to the 9 MHz board, just after the conversion to 9 MHz on the RF board.  Thus it is acting in cascade with the other 9 MHz filters downstream.

73,
Chuck  NI0C