[TenTec] Orion 2 100hz off

Sun Jan 1 15:14:36 EST 2023

To add to what Scott has posted, I thought I would share my quantified results so that we know what exactly to expect, even in the best-case scenario.

Please keep in mind that these results come from a 15 year old rig, and not ALL of the electrolytics have been replaced.  I imagine that there may be some other components that show use and age, as well.

Methodology:
In my case I quantified the results by transmitting 1 W of an AM signal into an HP 5384A 8-digit precision frequency counter.  The clock on this frequency counter is controlled by a 10MHz timing signal from an HP 53508A GPS clock.  The only way for this to be any more accurate might be to use more modern equipment, and even then it may not be any better.

Here's what to expect:

Position is important:
Adjusting the rig while it's on its side isn't going to result in any accuracy.  You're going to find that as soon as you flip it back to its operating position, the TCXO adjustments will have become invalid.  I'm not going to get into the potential physics of the situation.  Since the TCXO screw adjustment is accessed from the bottom, we have to flip the rig on its back in order to access it and to make accurate and sustainable adjustments.  This is OK, though.  Flipping it back over to check resulted in minimal to no difference at all.  Personally, I like to adjust the TCXO while the rig is on its back, and the rear of the rig is at a slight incline.  This puts the rig in the "inverse" position that it would be in if it were set up on my desk with the stand deployed.

Temperature DOES affect things:
The adjustments that the TCXO makes are not 100% linear, and are therefore not 100% accurate.  This is why more expensive stuff uses an OCXO (or even GPS timing) instead of a TCXO.  I even noticed a difference between the temperature on my bench vs the temperature in the rig's installed location.  Other equipment in the vicinity will also affect things, as they generate heat.  In my case I have a Yaesu FTDX-101D stacked on top of my Orion II.  Less equipment around or on top of the rig will result in a more predictable outcome.

Below is the difference between my bench adjustment, and the rigs final install location:
On the bench:
+3 Hz deviation         10M
+1 Hz deviation         12M
+1 Hz deviation         15M
+1 Hz deviation         17M
+1 Hz deviation         20M
+/- 0 Hz deviation        30M
+1.6 Hz deviation               40M
+2.6 Hz deviation               80M
+2.8 Hz deviation               160M

On the desk (operating position, both rigs powered on for several hours):
-5 Hz deviation         10M
-6 Hz deviation         12M
-3 Hz deviation         15M
-5 Hz deviation          17M
-7 Hz deviation         20M
-6 Hz deviation         30M
-3 Hz deviation         40M
+0.4 Hz deviation       80M
+1.9 Hz deviation       160M

These results are well within specification.

Now, let's compare this with my FTDX-101D as it came from the factory:
-8 Hz deviation          10M
-7 Hz deviation         12M
-6 Hz deviation         15M
-5 Hz deviation         17M
-4 Hz deviation         20M
-3 Hz deviation         30M
-2 Hz deviation         40M
-2.1 deviation Hz        80M
-0.6 deviation Hz       160M

As we can see, the results on the Orion II aren't all that bad.  Of course, the FTDX-101D is infinitely easier to adjust—you don't even need a screwdriver!

Finally, know that you're not going to be able to get it perfect for each band.  Not only is the adjustment screw tiny, and even the slightest turn can have a larger effect that we would like, the TCXO adjustment will compensate each band at a slightly different rate.  Getting 10m perfect will likely result in 160m being WAY off.  Get it as good as you can and try to aim for the bands you use most often.  Patience is the key.

________________________________
From: TenTec <tentec-bounces+k4vbb=live.com at contesting.com> on behalf of ronc at sonic.net <ronc at sonic.net>
Sent: Sunday, January 1, 2023 1:20 PM
To: 'Discussion of Ten-Tec Equipment' <tentec at contesting.com>
Subject: Re: [TenTec] Orion 2 100hz off

Scott:

You have probably already done this, but please read my tutorial on tuning
TXCO calibration on the Orion II:

http://n6ie.com/my-orion-txco-calibration-procedure.html

It might be helpful.  Also in the website is my fix for the frequency drift
that occurs during warm-up.

       Ron
      N6IE
www.N6IE.com<http://www.N6IE.com>

Member:
                  ARRL
     Redwood Empire DX Assn.
Northern California Contest Club
Northern California DX Foundation
    DXCC Honor Roll - 337/345
  Society of Broadcast Engineers

-----Original Message-----
From: TenTec <tentec-bounces+ronc=sonic.net at contesting.com> On Behalf Of
Scott Sheppard
Sent: Sunday, January 1, 2023 9:53 AM
To: tentec at contesting.com
Subject: [TenTec] Orion 2 100hz off

Thanks Marcus

I should have mentioned that I have duplicated the results using a brand new
Siglent 1032x Sig Gen...it duplicates the results shown with the smaller Gen
set.

It seems that to me, the issue is the actual adjustment ability
(range)  regardless of what it is being measured against. As I say, for a
given signal injected at a freq on 20m band, the lowest tone I can get on my
audio analyzer is about 697 hz...any adjustment whatsoever, and no matter
how careful, causes the tone to rise. You can turn the adjustment screw full
circle through its range and eventually come back to its 'closest setting'
of about 697hz again. I agree that nothing is broken per se, and the radio
works like a champ; if that tcxo began at around 597hz I'd have the range to
fix the issue.

Hope the above makes sense...and I love the reference. That was a great
movie!

Scott
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