These things drift over time, but I can't imagine that it drifted THAT much.
The first thing I would do is to measure the input voltage to the TCXO. Make
sure it's at spec. Problem is, I don't know what that voltage should be, and
the A10 board schematic doesn't appear to have that information readily
available. The TCXO appears to be run by a 74AC00 NAND gate chip. Someone
with more knowledge in this area "may" be able to extrapolate what that voltage
should be from the datasheet
(https://www.onsemi.com/pdf/datasheet/74act00-d.pdf) and the schematic.
Knowing the "REF EN" voltage supplying the NAND gate would likely help, and
someone with more patience than I have could likely follow this back and find
out.
What I can say is that rebuilding the A9 board solved a myriad of oddities with
my rig. It is entirely possible that a re-cap of that board might solve your
problem, since that board is responsible for providing stable power to the rest
of the rig.
74ACT000 - Quad 2-Input NAND Gate -
Onsemi<https://www.onsemi.com/pdf/datasheet/74act00-d.pdf>
74AC00, 74ACT00 www.onsemi.com 3 DC ELECTRICAL CHARACTERISTICS FOR AC Symbol
Parameter V CC (V) Conditions T A = +25°C T A = −40°C to +85°C Typ. Guaranteed
Limits Unit VIH Minimum HIGH Level Input Voltage 3.0 VOUT = 0.1 V or VCC − 0.1
V 1.5 2.1 2.1 V 4.5 2.25 3.15 3.15
www.onsemi.com
________________________________
From: TenTec <tentec-bounces+k4vbb=live.com@contesting.com> on behalf of Scott
Sheppard <scott.vy1co@gmail.com>
Sent: Monday, December 26, 2022 6:55 PM
To: tentec@contesting.com <tentec@contesting.com>
Subject: [TenTec] Orion 2 100hz off
Hello everyone, and happy holidays.
I have a new to me Orion 2 that runs very well, albeit 100 off Freq.
I have read the information on the tcxo, but it seems there is no
adjustment left in it.. that is to say, it's set at the best position and
movement turning either way only increases the problem.
I would appreciate it if anyone has some alternative solutions I could try.
It's not the end of the world, but it would be nice to zero it in. ...I
remember having an Omni V with the N4PY v.2 chip...that was brilliant as it
let you simply adjust the display to correct for crystal aging...
73 to all.
Scott. Vy1co
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