I just went and visited their website, and see they also offer a "kit OCXO"
from mostly through-hole parts and PCB. The OCXO insulation box is made out
of PCB, the thermostat is simply a jellybean TO92 transistor, and the 27MHz
crystal is an AT-cut being operated around 45C, so nothing awful
time-nutty, but still pretty neat that it's a kit. Details at

http://qrp-labs.com/images/ocxokit/ocxosynth_assembly.pdf

show that it walks about 14ppm during warmup and then might be good to a
ppm or so.

Tim N3QE

On Sat, Oct 22, 2016 at 10:02 AM, Giuseppe Marullo giuseppe@marullo.it
wrote:

Hi

Unfortunately, it could be lots worse (like many orders of magnitude worse). It all depends on which parameter you
are looking at and how much you want to add on to it. Phase noise and second to second stability are two areas that
it is likely to have problems.

The easy way is to manually calibrate a 10 MHz OCXO to GPS. If you have a scope, it isn’t all that hard.
Total cost is about $10 or so. The net result (free running OCXO) will be much cleaner than a simple GPSDO.

Bob

On Sat, Oct 22, 2016 at 7:02 AM, Giuseppe Marullo giuseppe@marullo.it
wrote:

For HF this thing is more useful than a 10MHz reference because it can
directly output any frequency in the HF band.

It is basically a GPS locked VFO.  I've seen this chip used in an SDR front
end is the VFO.  The chip's signal went into a mixer and translated the RF
to baseband in one step.  It is very stable but with the
"kind-of-square-like" waveform it is rich in harmonics and needs to be
filtered.

--

Chris Albertson
Redondo Beach, California

You have to remember what this thing replaces.  In ham radio, some people
are using vacuum tube oscillators with mechanical variable capacitor
tuning.  Maybe some advanced rigs use gear drive on the capacitor shaft to
allow more exact tuning  This Si chip is considerably better then 1940's
technology.

--

Chris Albertson
Redondo Beach, California

You need to catch up on what hams are REALLY using.

On Saturday, October 22, 2016, Chris Albertson albertson.chris@gmail.com
wrote:

--
If you gaze long into an abyss, your coffee will get cold.

On 22 October 2016 at 17:22, Chris Albertson albertson.chris@gmail.com
wrote:

Well, as someone else pointed out, hams are not using this sort of thing
now - or at least not in any significant numbers.

I recently bought a "new" 2 m transceiver - which is actually a 40 year old
Yaesu FT-225RD. When fitted with a Mutek front end (GW4DGU), they were
arguably the best 2 m transceiver ever made.

Mine drifts quite a bit, and I need to look into why. It can be two things

• Crystal - 100 and odd MHz
• VFO  - around 8 MHz

I heard of someone replacing the VFO with a cheap Chinese DDS as an
"upgrade". Actually, I suspect it was probably a downgrade, as I would
expect the VFO to be a lot cleaner.

I've not taken it apart to fix mine, but from what I have read, it would
appear the crystal is the main source of drift, and not the VFO. A
frequency counter will soon determine if that's the case in mine.

Dave

On Sat, 22 Oct 2016 10:34:53 -0400
Tim Shoppa tshoppa@gmail.com wrote:

It's funny how you can tell from the transistors used, where the designer
is from (BC547 -> European :-)

Kits like these have been around ever since I remember. This is one of
the better ones, where the crytal isn't just soldered to some transistor,
but a whole "insulation box" built around it. In german we call these
things "Quarzofen" (lit. "quartz oven") and that's IMHO a very precise
description what they are :-)

Generally it's not very difficult to build some kind of temperature
stabilization system. Heck, just using a heater transistor with a
constant current through it will give you a more stable temperature,
even if you don't control the current other than keeping it constant.
Puting some form of box around it that restricts air and thus heat flow
will make it even better. Using some temperature control and you are
within 1-2°C of stability and way better than most hams need.

The difficulty starts when you need more than that, when you need
temperature stabilities below 1°C, when you want to keep it stable
to 1mK or even below that.

BTW: If anyone has recomended texts on how to build stable ovens
for crystals, I'd like to hear about them. I've alread had a look
at what Rick Karlquist wrote, but I would also like to read more.
Unfortunately, good stuff literature is, as often, hard to find.

On Sat, 22 Oct 2016 17:04:19 -0400
"William H. Fite" omniryx@gmail.com wrote:

What hams have been using varies a lot. As much as what time-nuts are using,
or probably even more. I know a few people who still build valve PAs because
they are "indestructible" (aka can take a lot of abuse without damage).
But I also know people who do designs that are at the border of what
is technically possible today.

			Attila Kinali

--
Malek's Law:
Any simple idea will be worded in the most complicated way.

Hi

The bigger issue with doing a “home brew” OCXO is getting crystals with
known turn temperatures in a reasonable range for the project. Yes, you
can build gear to do temperature runs on crystals and sort bags full of them.
It’s likely that your whole bag of 5,000 came from the same bar and your
net result will all look a lot alike…..

Bob

Thanks to all that have answered, as usual very good advices.

I am puzzled about what to do, still the total cost of it for a OXCO +
GPS(unit with antenna) + control mcu is 67usd, I doubt I could find
anything like this for a cheaper price new.

Only cheap alternative could be this one(already discussed here one year
ago):

http://www.ebay.com/itm/141734507722?_trksid=p2057872.m2749.l2649

Would this allow me to play as the "standard" ThunderBolt using the same
software? Any preferred model among
63090/73090/65256 "models"?

Giuseppe Marullo
IW2JWW - JN45RQ

PS: Still I like the idea of the kit...the trimble would require PSU,
antenna, boxing and no fancy display...

On 10/22/2016 4:02 PM, Giuseppe Marullo wrote: