Hi Dan
how many of these oscillators have that low freq.hum?
73
KJ6UHN
Alex
On 2/27/2016 6:25 PM, Daniel Watson wrote:
Hi,
Attached is a plot of the output frequency difference from 10MHz during
warm-up. I believe this indicates the crystal is SC cut.
The VREF and EFC pins on the unit do work. The VREF is 4.1V.
I probed around the board of the unit I cracked open and found a low
frequency oscillation. It seems to vary from 40 to 90 Hz depending on where
the unit is in the warm-up cycle, and what I'm doing to it. With the can
cut off, the unit draws almost 50% more power than normal trying to
maintain temperature, so it's possible this is offset from what has been
reported in normal units.
In the photos, you may have noticed two sets of large, unpopulated pads on
the board near the output. I experimented with putting 10uF capacitors
across those. That killed the output, but the low frequency oscillation
could still be detected further back in the circuit.
Dan
On Sat, Feb 27, 2016 at 1:10 PM, Joseph Gray <jg...@zianet.com> wrote:
Nice teardown. I was looking at that listing just yesterday. I am tempted,
but don't know what I'd do with 40.
The real question is, how do they perform?
Joe Gray
W5JG
On Feb 27, 2016 9:48 AM, "Daniel Watson" <watsondani...@gmail.com> wrote:
Hi,
I'm sure many of you are tracking the cheap CTS 10MHz OCXOs available on
eBay right now. I purchased a case of them, and decided to crack one
open.
I took pictures along the way, thinking that might be interesting to the
list. Here is the blog post if you are interested:
http://syncchannel.blogspot.com/2016/02/10mhz-ocxo-teardown-cts-1960017.html
Comments on the internal construction of the OCXO are welcome. It seems
pretty straightforward inside though.
Best regards,
Dan W.
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