[TenTec] God Bless the model 221 filter

[Clark Savage Turner]

Awoke this morning at about 4 am, a little earlier than
usual.  Got up and kicked up the OMNI VI and listened around
on 40 CW, noticed the QRP contest going on.  Fiddled with
the filters, I am a confirmed INRAD user, but I have the
Ten Tec model 221, 250 Hz filter in the 9 MHz IF (centered
at some 500 Hz tone) and needed to dig out the weak ones
in the noise and SSB QRM near the frequency.  I finally
heard a serious difference in ringing.  The model 221 250 Hz
filter just seems to ring a little less than the INRAD 400 Hz
filter.  It made some real difference to my ears.

I also have the model 217, 500 Hz filter and stuck it next
to the INRAD 400 Hz filter.  I could hear a difference in
the center frequency / "sound" of the ringing (the rumbling
of the INRAD filter versus more high pitched sloshing from
the Ten Tec filter) but it was not a big difference.  Wish
I had an INRAD 250 filter for the 9 MHz IF to compare the
model 221 to.  

All I can say is the model 221 filter from Ten Tec really,
really helped me copy some weak ones by not ringing and 
covering the weak signal so that my ears had a hard time.

I am interested in the difference between the ladder and
lattice filters in actuality, I may be hearing it here,
but I still have no good direct comparison.

Oh, and by the way, anyone have a spare model 705 mike they
would part with?  

Clark
WA3JPG


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