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563inrad [2007/04/23 16:19] n5na |
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| *[[http://www.qth.com/inrad/kits.htm#tentec|Inrad Omni VI / VI+ Roofing Filter Mod Page]] | *[[http://www.qth.com/inrad/kits.htm#tentec|Inrad Omni VI / VI+ Roofing Filter Mod Page]] | ||
| + | *{{omni_inrad_roofing_filter_switch_mod.pdf|K1FK's Inrad Roofing Filter Switch Mod}} | ||
| *[[http://tom.w4bqf.googlepages.com/roofingfilterforomni6plus|W4BQF Page on K1FK Mod to Inrad Instructions]] | *[[http://tom.w4bqf.googlepages.com/roofingfilterforomni6plus|W4BQF Page on K1FK Mod to Inrad Instructions]] | ||
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| + | **From the Inrad Reflector February 27, 2005** | ||
| + | |||
| + | An Inrad roofing filter mod. installed in the OMNI VI/VI+ renders the NB function inoperative. | ||
| + | |||
| + | The reason for this is that the noise pulse is stretched in width by more than 2000 times as it passes through the front end circuits and the narrow (either 600 Hz or 2.4 kHz) roofing filter. For example, a 0.5 µS noise pulse appearing at the antenna input is stretched to several mS as it passes through a 500 Hz wide filter inserted in front of the OEM 15 kHz roofing filter. Since the signal pickoff for the NB function remains after the OEM roofing filter, the NB circuitry sees this lengthened noise pulse, which it is not designed to process. | ||
| + | |||
| + | My own roofing filter (home brew 4-pole, 500 Hz BW, centered @ 9.000500 MHz) is selectable from the front panel using the PROC button. This facilitates selection of the Inrad #753 (400 Hz BW) or TT #221 (250 Hz BW) filters with the N1/N2 buttons independent of the roofing filter and permits use of the NB (if needed) by deselecting the PROC. | ||
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| + | Since I do not operate SSB, this is not a problem (for me) with the narrow filter. If one were to install the Inrad 2.4 kHz roofing filter mod, the Processor function would not be disturbed with the PROC selected, however the 2.4 kHz roofing filter would not provide optimum performance in the CW mode, and the NB function remains inoperative with the roofing filter mod. selected. | ||
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| + | BTW: The FM receive mode is also inoperative with the roofing filter mod. because of the narrow bandwidth preceding the FM receiver section; FSK mode is inoperative because of the roofing filter(s) incompatible offset(s). | ||
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| + | Dave, K1FK\\ | ||
| + | Fort Kent, ME | ||
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| ===== Ten-Tec Reflector Comments ===== | ===== Ten-Tec Reflector Comments ===== | ||
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| -the implementation needed to simply take the roofing filter selection off of the N1/N2 buttons, | -the implementation needed to simply take the roofing filter selection off of the N1/N2 buttons, | ||
| - | -without incurring any additional components, with a (3) minimum of effort, and (4) with minimal impact to other operating modes and functions. These requirements narrowed the design to only one choice of front panel switch . the PROC switch, which is a "hard" switch with push-push states. | + | -without incurring any additional components, with a |
| + | -minimum of effort, and | ||
| + | -with minimal impact to other operating modes and functions. These requirements narrowed the design to only one choice of front panel switch . the PROC switch, which is a "hard" switch with push-push states. | ||
| The question has been raised on the reflector as to why not use the FM or VOICE or other main keypad switches to select the Inrad roofing filter, switches that (appear to) have less of an impact on operational modes than the PROC switch. | The question has been raised on the reflector as to why not use the FM or VOICE or other main keypad switches to select the Inrad roofing filter, switches that (appear to) have less of an impact on operational modes than the PROC switch. | ||
