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@contesting.com> on behalf of
ronc@sonic.net <ronc@sonic.net>
Sent: Sunday, January 1, 2023 1:20 PM
To: 'Discussion of Ten-Tec Equipment' <tentec@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@contesting.com> On Behalf Of
Scott Sheppard
Sent: Sunday, January 1, 2023 9:53 AM
To: tentec@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
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|