Hello to all members.
And also remember that properly applied, a Zener diode can be a very
good reference. This might be more in the Volt--Nuts class, but the
Solartron 7081 8.5 digit DVM uses a TC Zener as a voltage reference. Of
course it is a selected Zener with a carefully controlled
I forgot to mention that the TCZD regulators are affected by the power
supply too, depending on the rest of the circuit. I think they typically
had a two-stage deal, with a regular Zener to make a higher voltage, and
provide a fairly stable supply to operate the reference regulator, but
of
Andy wrote:
"... I too was surprised to see nothing more than a Zener being used in
one case, but bearing in mind this was in a temperature controlled
environment is not as bad as a Zener in open air."
In the OCXOs I've had opened up, they used a temperature compensated
Zener, typically in
And given the age of many OCXOs it was sort of the tool of the time. There
really were not better devices in the 60s and early 70s.
Regards
Paul
WB8TSL
On Sat, Dec 25, 2021 at 11:43 AM Andy Talbot wrote:
> In the (very) few OCXO circuits I've seen, voltage at both ends of the
> tuning varactor
In the (very) few OCXO circuits I've seen, voltage at both ends of the
tuning varactor are derived from the same internal voltage reference. So
any drift in this will, partially at least, cancel out.I too was
surprised to see nothing more than a Zener being used in one case, but
bearing in
Being also a bit of a volt-nut, I played a bit with the Vref output
from some of my OCXO's and must sadly report that they were not
spectacular, seen from a volt-nut perspective.
In at least once case, an admittedly pretty old OCXO design, the
voltage reference was not located in the most
Hi
> On Dec 24, 2021, at 4:26 AM, Hal Murray wrote:
>
>
> kb...@n1k.org said:
>> The gotcha is the common ground found on most OCXO???s. Putting the oven
>> current through that ground makes keeping the Vref (and the EFC) well behaved
>> a bit of a chore. For various reasons OEM???s have a
kb...@n1k.org said:
> The gotcha is the common ground found on most OCXO???s. Putting the oven
> current through that ground makes keeping the Vref (and the EFC) well behaved
> a bit of a chore. For various reasons OEM???s have a hard time dealing with
> multiple grounds that have multiple
When I designed the HP E1938A, I put a 2.5V reference IC inside the oven
and brought out both terminals of it. This was intended to provide a
reference voltage to the external DAC that generated the tuning voltage
for the loop that locked it loosely to GPS. It had its own return path
that
One thing I've seen on several OCXO and small Rbs is that the EFC pin is
internally wired in the middle of a voltage divider using two fairly
high value (>10K) resistors between Vref and ground. That ties the
varactor to the middle of the EFC range when no external tuning is
required. For
Hi:
I'd second this. When I was working at HP on the Kobe Instrument Division products (component testers) the 4352S VCO
tester had a very special power supply for the tuning voltage that was extremely clean so as not to detract from the VCO
under test.
--
Have Fun,
Brooke Clarke, N6GCE
> On 23 Dec 2021, at 18:47, Attila Kinali wrote:
>
> On Thu, 23 Dec 2021 14:42:27 +0100
> Wilko Bulte wrote:
>
>> A quick experiment learned that the OCXO freq responds to the EFC voltage.
>> So, looks like the Vref circuit in the OCXO has died.
>
> A stupid side question: Why do have
I've always assumed this is because they need to know the reference is
clean and under the OCXO manufacturer's control if it's to meet specs. If
the user had to supply the reference there's no knowing how clean it is.
Andy
www.g4jnt.com
On Thu, 23 Dec 2021 at 17:47, Attila Kinali wrote:
>
Plus it was temperature stabilised since it was in the oven area.
Regards
Paul
WB8TSL
On Thu, Dec 23, 2021 at 2:16 PM ed breya wrote:
> Many of the older VTOCXOs have the internal reference voltage accessible
> simply to use them stand-alone. A remote adjustment pot could be fed
> from the
Many of the older VTOCXOs have the internal reference voltage accessible
simply to use them stand-alone. A remote adjustment pot could be fed
from the reference, and set the fine tuning voltage, without needing any
other support from the system. Nowadays we typically tune from PLLs, and
such,
Hi
The main reason OCXO’s have a Vref is that an ovenized
voltage source is likely to be more stable over temperature
than what you can easily buy and mount on a PCB.
The gotcha is the common ground found on most OCXO’s.
Putting the oven current through that ground makes keeping
the Vref (and
16 matches
Mail list logo
