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
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|