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Fw: [TenTec] 500hz FSK filter

To: <tentec@contesting.com>
Subject: Fw: [TenTec] 500hz FSK filter
From: EdGuzis@cris.com (Ed Guzis .)
Date: Mon, 12 Jan 1998 16:34:34 -0600
Please reply directly to Duane, AC5AA at <dcalvin@vnet.IBM.COM>.  This is a
forwarded message.

Ed Guzis, W9TW <w9tw@contesting.com>
Tentec Mail Reflector Administrator
From: dcalvin@vnet.IBM.COM
Subject: [TenTec]  500hz FSK filter
To: <tentec@contesting.com>
Date: Monday, January 12, 1998 8:56 AM

Hmm, I must have been out to lunch when that topic was taught.  I thought
the 500 Hz digital filter was for the first IF - the 9 MHz one without
passband tuning.  And that the reason for it was so you could cascade
the 6 MHz 500 Hz filter (via PBT) with it and get the tighter skirts on
RTTY.  Since it's untunable, the 9 MHz filter must be built centered on
the correct frequency to get both tones within the skirts.  So, that
meant that you could use the 6 MHz 500 Hz filter alone, or could cascade
it with the 9 MHz RTTY filter.  (I sure hope that when they look at
an Omni-7 design they consider offsetting that frequency in the rig so
the same filters could be used.  One of the things I liked a lot about
the IC-765...)

Again, maybe I completely misunderstand this scheme.

 73,  Duane    AC5AA

Duane A. Calvin
dcalvin@austin.ibm.com -or- dcalvin@ausvmr.vnet.ibm.com
Subject: [TenTec]  500hz FSK filter
To: <tentec@contesting.com>
Date: Sun, 11 Jan 1998 22:18:06 -0600
From: Richard Westerman <GoWest@classic.msn.com>
Subject: [TenTec] 500hz FSK filter
To: <tentec@contesting.com>
Date: Sunday, January 11, 1998 1:41 PM

The regular 500 Hz cw filter works just fine for RTTY/Packet/etc., but
you've probably noticed that you have to tune the PBT to adjust the RTTY
signal so that it is centered within the passband of the filter.  With the
data mode filter, the signals should be centered without retuning the PBT. 
That's the only difference.

Also, you can use the data filter for receiving CW, but in this case, you
retune the PBT to place the CW signal in the center of the passband.

HOWEVER, the catch is, if you have a 500 Hz data filter and a 250 Hz CW
filter and are working in CW mode, each time you switch between filters,
you have to retune the PBT and that's a pain.

I'll stick with the 2x CW filter and retune when using RTTY.


From: Bill Straw <WB0O/0007359114@MCIMAIL.COM>
Subject: Ten Tec 500hz FSK filter
To: <tentec@contesting.com>
Date: Friday, January 09, 1998 7:33 PM

   I've started to get the RTTY bug here lately, even
operated the ARRL RTTY Roundup and had a good time. MY
software/hardware runs the OMNI VI in the LSB position
for the RTTY (AFSK), and seems to do just fine with the
regular 500 hz or 250 HZ in line. Now I read where
there is a "special" FSK 500 hz filter than can be put
in the "narrow" position, which is unused on my setup.
   Will this filter help me, and is it worth $89 for
whatever it will help with ???


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