[TenTec] Orion 2 100hz off
Marcus Florido
k4vbb at LIVE.COM
Fri Dec 30 18:43:07 EST 2022
Ok,
I've taken a better look at the schematic here. Working backwards from the TCXO:
Taking the resistor at R80 into account, you should be reading 4.6 to 4.7 V at pin 14 of the TCXO.
The supply voltage to the TCXO (at pin 14) comes from pin 1 of the voltage regulator at U10. This is a 78L05, which should supply between 4.8 V at the very low end, and a maximum of 5.2 V. A nominal reading at pin 1 on this voltage regulator should be 5 V.
If it's not, check the supply voltage on pin 8 of U10. This should read close to 10V. The U10 regulator is supplied 10 V from U1, which is another regulator further up the chain, and it is an LM2940T-10. U1's only purpose in life is to supply U10 with 10 V. U10 in turn regulates the voltage down to a constant 5V for use by the TCXO and some other stuff in the reference divider circuitry.
If you're not reading very close to 10 V at pin 8 on U10, then check IT'S input voltage at pin 1. This should be very close to 12 V.
The NAND gates after the TCXO are only there to provide some sort of buffer to U7, which is some kind of DDS chip.
SO:
In the end it's going to be one of 2 things:
--you have a voltage supply problem somewhere in the TCXO power supply chain
--your TCXO has drifted too far to be able to adjust correctly.
If this is a supply voltage issue, it is less likely that the problem is on the A10 board. I don't recall seeing any electrolytics of the type that like to leak and die on the A10 board. And while it's possible that one of the capacitors around the voltage regulators might be bad, it is MUCH more likely that the voltage supplied to the board is the issue, in which case you should start tracing the 12 V back from J1. As many of us have found already, you'll likely find that the 12 V output on the A9 board is 'off' or unstable.
If this is a TCXO problem, you'll have to source another TCXO to fix it. Thankfully, Ten Tec didn't use a bunch of proprietary parts, and although this is an odd-ball frequency, you "might" be able to find a compatible TCXO.
Now, for the practical part:
I'm not going to take my Orion II apart to see, but I don't think that any of the testing locations are easily accessible while the board is installed. I may be wrong, and for your sake I hope I am. If they are not, you might have to remove the board and VERY CAREFULLY supply a REGULATED 12 V to the board via J1. This way you can flip the board over to access the solder joints where everything connects. Do not try to power it with the 13.8 V from your power supply.
Good luck.
K4VBB
________________________________
From: TenTec <tentec-bounces+k4vbb=live.com at contesting.com> on behalf of Michael Cheponis <michael.cheponis at gmail.com>
Sent: Friday, December 30, 2022 2:05 PM
To: Discussion of Ten-Tec Equipment <tentec at contesting.com>
Cc: Byron Cordes <byroncordes at icloud.com>
Subject: Re: [TenTec] Orion 2 100hz off
I'm pretty sure the only caps you need to change are those low ESR types on
A9. Just look at the spec sheet, choose low ESR, up the working voltage by
1.5 times the original, buy quality (Nichicon, Panasonic, Kemet, Vishay,
AVX, Rubycon, etc).
Minimize ESR:
https://www.avnet.com/wps/portal/abacus/resources/article/understanding-esr-in-electrolytic-capacitors/
; the article mentions another technique to reduce ESR, which is to
parallel two caps to get your required C value.
Generally, the ceramic caps are OK, as are the tantalums (unless they were
from that particular bad batch at the time).
Summary, replace with:
1) Lower ESR
2) Higher Working Voltage by a factor of at least 1.5
3) Maybe slightly (< 10%) higher Capacitance -- but don't go crazy, unless
you analyze / simulate the circuits and make sure it'd work.
--------
Years ago, I built a small accessory for Panasonic, and put some 10V caps
on a 5V rail, and got raked over the coals by Japanese engineers because,
why wasn't that a 16V cap on the 5V rail? Was I an imbecile who did not
know that the rule at Panasonic was WV >= 3X actual circuit voltage? I
definitely fixed that in the release model. Also, these days, I try buy
Panasonic electronic stuff, because if they pay that much attention to
detail...
Mike K6THZ
On Fri, Dec 30, 2022 at 10:48 AM Byron Cordes via TenTec <
tentec at contesting.com> wrote:
> Be sure to replace those caps with good ones . I buy from Mouser when I
> want good stuff . Not saying it is but I think I have a better chance. I
> also get 10 at a time . Somebody seems in need of a good cap almost every
> month or two around here .
> 73s Byron AC9PA
>
> On Dec 30, 2022, at 11:39 AM, Scott Sheppard <scott.vy1co at gmail.com>
> wrote:
>
> Thanks Marcus
>
> I think for certain it's associated to what you are suggesting...I had
> earlier dropped a note to the radiosmith, steve, who kindly replied he had
> seen that issue in an Orion, but not yet on a O2. He too said to check the
> Voltages going into the tcxo-- which I did...they are bang on by 'my'
> measurements.
>
> The A9 in this rig is a replacement board but still has the smaller caps. I
> plan to replace those as soon as I get the parts...it needs to be done
> anyway.
>
> Thank you for taking the time to reply.
>
> Happy New Year
>
> Scott. Vy1co
>
> On Fri., Dec. 30, 2022, 10:00 a.m. , <tentec-request at contesting.com>
> wrote:
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> > 1. Re: Orion 2 100hz off (Marcus Florido)
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> > ----------------------------------------------------------------------
> >
> > Message: 1
> > Date: Fri, 30 Dec 2022 11:08:34 +0000
> > From: Marcus Florido <k4vbb at LIVE.COM>
> > To: "tentec at contesting.com" <tentec at contesting.com>
> > Subject: Re: [TenTec] Orion 2 100hz off
> > Message-ID:
> > <
> >
> CY4PR13MB122323FC0ADE608E2C1788258AF09 at CY4PR13MB1223.namprd13.prod.outlook.com
> >>
> >
> > Content-Type: text/plain; charset="utf-8"
> >
> > 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<http://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<http://www.onsemi.com>
> >
> > ________________________________
> > From: TenTec <tentec-bounces+k4vbb=live.com at contesting.com> on behalf of
> > Scott Sheppard <scott.vy1co at gmail.com>
> > Sent: Monday, December 26, 2022 6:55 PM
> > To: tentec at contesting.com <tentec at 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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