Differences

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--- 221 [2007/02/13 22:12]
n5na created
+++ 221 [2011/12/02 11:39] (current)
n1eu [Additional Information]
@@ Line 1: / Line 1: @@
 ====== 9 MHz 6 Pole 250 Hz Crystal Filter Model 221 ======
-Special 250 Hz filter with the passband centered on 500 Hz rather than 750 Hz.  Same as 219 except for the passband.
+Special 250 Hz filter with the passband centered on 500 Hz rather than 750 Hz.  Same as 219 except for the passband frequency.
 ===== Specifications =====
 | Center Frequency        |  9.000500 |
 | 6 dB BW, Hz             |  250 |
-| Shape Factor, 6/60 dB   |  3.5:1 |
+| Shape Factor, 6/60 dB   |  2.4:1 |
-| Insertion Loss, dB      |  14.0 |
+| Insertion Loss, dB      |  10.0 |
 | Ultimate Rejection, dB  |  85+ |
 | Z in & out, Ohms        |  200 |
 | Number of Poles         |  6 |
+===== Additional Information =====
+**From Scott Robbins, W4PA, on the Ten-Tec Reflector February 17, 1998:**
+As regular readers of the reflector, you've probably seen the thread
+about a group of hams contracting with our filter manufacturer, through
+Ten-Tec, to have an alternate center frequency 250 Hz 9 MHz I-F filter
+built for use with the Omni-VI and Omni-VI Plus.  Tyler Barnett, N4TY,
+gathered the group and then contacted us about the possibility of
+Ten-Tec's engineers providing our filter manufacturer with the needed
+specs and to see if we could obtain a reasonable price for the filter
+as well.
+The idea for an alternate passband center frequency CW filter is not a
+new one.  We did a survey via the Internet reflector about a year ago to
+see where our Omni-VI owners run the offset in an attempt to determine
+whether it was feasible for us to offer alternate passband center filters
+for the transceiver.  This was after a couple of groups of hams had
+contracted independent of us with our filter manufacturer to build a 9 MHz
+I-F, 500 Hz bandwidth, 500 Hz passband centered filter.  (Which, of course,
+was fine with us as we had no interest in doing them ourselves).
+Our standard 9 MHz I-F filters are passband centered at 750 Hz.  This
+becomes somewhat problematic when running the Omni-VI or VI-Plus at a
+lower CW offset (400-550 Hz).  Using a low offset, when 250 Hz bandwidth
+filters in both I-F's are cascaded together the signal tends to slip off
+the edge of the filter.
+After some discussion with the filter manufacturer they indicated to us
+that despite the filter being a "special order" item that they would be
+willing to extend us our usual quantity discount for the new filter.
+Which, I must admit, we were surprised and pleased to hear!  The main
+sticking point in the past for us to offer alternate passband
+centered filters was the possibility that we would have to stock the
+item at a significantly higher price than the rest of the crystal
+filters we offer for the Omni-VI/Omni-VI Plus.
+We'll be offering the new filter at $89, same price as all other crystal
+filters available for the Omni-VI/Omni-VI Plus.  The specs for this
+filter are the same as the #219 250 Hz CW filter, except the passband
+is centered at 500 Hz rather than 750 Hz.  Who benefits?  If you often
+use a pair of 250 Hz filters, with a low CW offset, you may find this
+filter to be to your advantage.  If you usually run the offset at 600 Hz
+or higher, you'll find no benefit from having the new #221 in place of
+the #219.
+This is not a "one-time" offer; we will be stocking this filter as a permanent
+addition to the line.
+//(note: my #221 filter has a measured center freq of 450hz - N1EU)//

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