[TenTec] 6.3 MHz xtal filter... TT 288??

[Jon Iza <jon.iza@gmail.com>]

Folks,
I have just got an 8-pole 6.3 MHz filter. It carries on the PCB the
reference number 6840. On top, the reference cannot be read. Along
with 8 crystals marked Green-red-black-blue-blue-black-red-green,
there are 7 caps marked as follows:
101 NP0, 131 NP0, 151 N750, 151 N750, 151 N750, 131 NP0, and 101 NP0.
It sounds like an SSB filter, narrower than the regular one, BUT,
instead of chopping up the higher tones, it chops down the lower
tones.
I have read there was a special filter done for RTTY at 9MHz. But, may
this be something similar for 6.3 MHz?
Inquiring minds wanna know...
jon, ea2sn