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[TenTec] Scout drift fix?

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Subject: [TenTec] Scout drift fix?
From: rohre@arlut.utexas.edu (Stuart Rohre)
Date: Mon, 16 Jul 2001 14:11:56 -0500
The so called Scout drift is covered in the manual.  Also, the Scout
requires a good 13. Volt auto supply, and will drift if you go below 11
volts, but that is a function of the voltage regulator.  More modern
regulator chips with lower overhead voltage requirement would help this.

It does not do any noticeable on phone in normal use, at Ten Tec suggested
supply voltages with adequate wires.

The feature "drift"  is an artifact only on high speed CW greater than 20
wpm, or that CW without any pauses.  The cause is the frequency update
circuit shares the same microcontroller as the keyer.  If the keyer is
taking all the interrupts, the computer cannot act to gradually keep the
frequency from a "jump".  The jump is the late update for the PTO by the
micro.

There are a couple of things that minimize this.  One is to add a fan on the
heat sink area, for dramatic improvement, (at full power).  The other
involves optimization of the NPO caps in the PTO (oscillator) circuit.  The
fixes are in the Ten Tec reflector archives as they were widely discussed
here within the past 5 years.
GL and 73,
Stuart K5KVH



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