[TenTec] Orion 2 100hz off

[Marcus Florido]

I'm not 100% sure that there is anything wrong with the rig at this point.  I think that with a change-up in methodology you can get this thing adjusted.

I use a GPS-clock enabled frequency counter to adjust my rigs.  I "cheat", and simply TX into it with 1 W on AM and adjust the TCXO from there.  This is "dead-on balls accurate", to quote Mona Lisa Vito (movie reference).  I don't bother with WWV and USB/LSB balance simply because I have the equipment available to do it the easy way.  I've also used an HP signal generator that is also GPS clock stabilized before, but I find that the TX on AM method is much faster.

But, not everyone has all this stuff.

The stability or accuracy is not known on the XG3, especially if you're using it on battery power.  If it isn't hooked up to a clock, then it must have an internal clock.  The only ones that I know that are both accurate and stable enough to calibrate with are the ones with an OCXO in them, or ones with the ability to take in a 10mHz timing signal from a GPS.  This thing looks pretty small to have an OCXO in it, and I didn't see a hook-up for an external time reference.  I'm not saying that it ISN'T accurate, just that there's no real way to tell.

If it were me, here's what I would do if I had another HF rig available that was reasonably accurate, and has a TCXO installed in it (most modern rigs do):

Take your other HF rig and tune it to at least the 15m band, nothing lower.  (The higher the frequency you're using, the better the accuracy.  There is a trade-off, though.  The higher in frequency you go, the harder it is to turn that tiny screw in the amounts that you need to get it right.  If you have a steady hand, go for a frequency on 10m.)

--Turn the output power down as low as it'll go.
--Disconnect any microphones from that rig, and make sure that there is no audio input to modulate the signal.
--Transmit on any frequency on the band of your choice (my preference is something in the 15m band) into an antenna on AM.
--Tune your Orion II to the same frequency and listen.  Make sure that XIT/RIT is OFF.
--On AM you should hear nothing.
--Change the operating mode to UCW.  You should hear a tone.
--Change the operating mode to LCW.  You should hear a tone here, as well.  However, it is likely at a different pitch.
--Adjust the TCXO so that the pitch is the same, or as close as you can get it, between UCW and LCW.

Note that without a calibrated reference, the adjustments you make will only be as accurate as the rig you're using as a reference.  Assuming the rig you're using as a reference is somewhat accurate, this should get you closer to where you need to be on the Orion II.

If you don't have something reasonably accurate to use as a reference, you can try and use this same method with WWV.  If your WWV signal is good (unlike my location), then this may be a more accurate method.

Even with GPS stabilized clock-referenced equipment, the adjustment is so fine on this TCXO that you may not be able to get it 100% accurate.  Because of this you'll notice that the frequency deviation on different bands is off, and off by different amounts.  If you have the patience of a Saint, you may be able to dial it in exactly.  In case you don't, you'll have to quantify that deviation on every band and adjust the TCXO to a reasonable compromise setting that gets you close on every band.

K4VBB

________________________________
From: TenTec <tentec-bounces+k4vbb=live.com at contesting.com> on behalf of Scott Sheppard <scott.vy1co at gmail.com>
Sent: Saturday, December 31, 2022 11:49 PM
To: tentec at contesting.com <tentec at contesting.com>
Subject: [TenTec] Orion 2 100hz off

I truly appreciate all the assistance offered to date--on or off list.

The situation is as follows with respect to the tcxo on the Orion 2:

A station transmitting on upper sideband--say 14 140.00 will sound
correct if I tune my dial to read 14.140.100  That is to say, I need
to tune my dial 100 hz higher than what the actual TX freq is. I work
mostly CW but no matter.

To date,  I have checked all the voltages immediately available to me
without removing the board etc and they seem fine. The main voltage
regulator is flat on 10v, and the voltage that appears to be servicing
the TCXO (from U10 that I cant get to?)  is just under 4.933v, and
just over 5 volt the other side of the R? (cant recall what number the
resistor was).

When I went in to tune the tcxo, I used my elecraft XG3 sig
gen--basic, but thats all I needed. It provided a s9 tone at 14.020.
On my audio analyzer, the best I could tune my 700 hz tone to was 697
and 703 hz LCW and UCW respectively...a difference of 6 hz.Tuning the
tcxo beyond that point, no matter how carefully, only increased the
offset from what the actual freq should be.

To summarize, across the bands I have checked,I have to compensate my
dial frequency 'X' hz higher to be on the other stns freq:

20m 100hz

40m   30 hz

80m   ~15hz

Additionally, the tcxo is not labeled as Siwart...the only reading is:

DFA18-HA
44.550 Mhz
A18006-3205

I hope this makes sense to those more familiar with the rig and those
more electronically inclined than myself!

Again, many thanks to all and the very best for the new Year from the
Wilds of the Yukon Territory.

Scott VY1CO
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