[TenTec] Rationale for the PROC selection of the Inrad Roofing Filter

[Charles Greene]

Good rationale Dave,

I had also decided to use the PROC switch, but I didn't know all the 
rationale behind it.  I need details of where to find the leads and how 
interface them to the Inrad filter.  I have the 600 Hz roofing filter.

Can you please send me some more details?

Tnx,

Chas, W1CG

At 01:26 PM 8/7/2005, you wrote:
>This is to clarify my rationale for using the PROC switch to activate the 
>Inrad roofing filter
>modification.  For those not familiar with the history of this, I 
>performed this modification to my
>Omni VI+ (opt 3) over 2-1/2 years ago while testing various home-designed 
>roofing filters, and
>needed a front panel selection capability so that I could record A/B test 
>data while still keeping
>the N1 (500 Hz) and N2 (250 Hz) filters independently selectable.
>
>
>
>The primary requirements (for the modification of the Inrad roofing filter 
>implementation) were:
>(1) the implementation needed to simply take the roofing filter selection 
>off of the N1/N2 buttons,
>(2) 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.
>
>
>
>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 first reason is that ALL of the main keypad switches are "soft" 
>switches, which are scanned by
>the microprocessor, and do not provide a permanent status of the selected 
>state.  Use of any of the
>soft switches for this modification would require an additional PC board 
>with buffer and latch
>circuits, contrary to requirements 1, 2 and 3, and would require removal 
>of the Logic Board in order
>to implement the interface in hardware.   Further, use of the FM button 
>would require a software
>change, as once the button is depressed; the radio is in the FM mode!
>
>
>
>Use of the VOICE button on the main keypad would, in addition to the above 
>four requirements,
>require the optional voice board to be installed, a further complication 
>of requirements 1-4.
>
>
>
>Dave, K1FK
>
>Fort Kent, ME