Interesting that there is a new part instead of the older Siward unit.
Siward no longer lists the device, so TT must have gone somewhere else. It
would be interesting to see the warm-up drift plot of the new unit vs. the
old one.
I think more folks would interested if they knew this would work...I wonder
if Abracon could be talked into giving you a free sample to evaluate? If
you could talk some ham magazine into letting you do an article, they would
sell a bunch of them. Or maybe with enough 'cajoling' Ten Tec might give
Abracon a call and take this project on with the idea of producing an
optional upgrade that could be added in the field or the factory. They can
order lots of 100 and get the price down lower.
I envision a small board for the the SMT that would be mounted to the
chassis somehow with stand-offs. It would have a simple PC-mounted plug
wires that could be soldered to the connection points used by the original
oscillator...all that's needed is output and ground...and a 'fly-lead' to
the +13.6 before the main power relay. To keep the oscillator running, a
simple voltage regulator like a 7805 with a couple of filter/RF bypass caps
and a fuse would be on the new board. External power might not be needed
since the unit fully stabilizes in < 2 minutes, which would make things
simpler. The board would also hold the adjusting pot. That's not much more
junk than my goofy fan mod!
Ron N6IE
www.N6IE.com
----- Original Message -----
From: "Linwood Davis" <linbdavis@earthlink.net>
To: "Ron Castro" <ronc@sonic.net>; "Discussion of Ten-Tec Equipment"
<tentec@contesting.com>
Sent: Tuesday, January 05, 2010 7:05 PM
Subject: Re: [TenTec] High stability frequency reference oscillator for
theOrion II
> Hi Ron,
>
> I did get a firm quote of $135 each for 10 pieces, with a 12 week lead
> time!
>
> You had a concern about the output. I asked for the LVCMOS output option
> to make it a little simpler, however some care is still needed.
>
> I checked the markings on the oscillator in my O II and found DFA18 HA,
> not the Siward part! And I can't find a data sheet for it but I am fairly
> certain that it was made by Fordahl.
>
> Yeah, power may have to be provided externally. I wasn't considering this
> at first, but keeping it warm all the time would be good. Let's see... the
> warm-up drift is 0.1ppm, or 1.4 hz on 20 meters. And the max. draw during
> warm-up is 3.6 W, roughly 3/4 amps at 5V. Not sure if we can pull this
> from the O II somewhere...
>
> Anyway, this may all be for naught, since there are still too few who are
> interested. Don't really want to shell out $1350 + shipping to make it
> happen.
>
> Lin,
> WB1AIW
>
> Ron Castro wrote:
>> I would be very interested in participating, and yes, I believe the
>> "original" Orion used the same oscillator. While the mod on my website
>> mitigates the problem considerably, it can't really cure it. Looking at
>> the spec sheet of the AOCJY, it appears to be available in the correct
>> operating voltage, excellent phase noise. The sine wave output is shown
>> at +2 dBm @ 50 Ohms output load while the original shows 1 V P-P into 10
>> k Ohms. This should probably be looked into. Here are the specs of the
>> Siward (I just noticed my website link needs to be changed):
>>
>> http://www.datasheetarchive.com/TXO32-datasheet.html
>>
>> Another minor problem is that the AOCJY appears to be an SMT device, so
>> some sort of PC board would need to be designed to convert the
>> architecture. That would be good though since the AOCJY accommodates an
>> external adjustment pot that should make calibration a breeze. Also
>> because since its an oven-controlled device, an external 5 or 3.3 VDC
>> regulator/filter will be needed along with a direct connection to 13.6
>> VDC so the oven stays on when the power switch is off.
>>
>> BTW...did you ever notice that most new Orions are 20 Hz off frequency on
>> 20 Meters? I heard that regularly on the TT Sunday net when I first
>> started checking in. That's apparently because when they are adjusted at
>> the factory, the radio is upside down with the cover off and the
>> compartment is at room temp. Normally that compartment gets to over 100
>> degrees F without the fan mod!
>>
>> A friendly call to TT might be in order to see if these specs will work,
>> and once done, you should have no trouble finding ten folks who want go
>> in.
>>
>> Ron N6IE
>> www.N6IE.com
>>
>>
>>
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