Hi
If we're talking about a basement TimeNut setup there are some things that
matter and some things that really don't:
Matters:
Load isolation matters. You can get > 45 degrees (> 12 ns) quite easily
with a load change
ADEV matters. Your frequency counter will not be happy wit
On 09/28/2013 02:24 PM, Didier Juges wrote:
> As always, be careful with the hard and fast rules. Most crystal oscillators
> generate sine waves first, but if the oscillator is part of a GPSDO, it will
> have to be converted to square to be processed by the logic within the GPSDO,
> so even if t
As always, be careful with the hard and fast rules. Most crystal oscillators
generate sine waves first, but if the oscillator is part of a GPSDO, it will
have to be converted to square to be processed by the logic within the GPSDO,
so even if the device has a sine output, there will be a square
Hi Tom,
The Jackson CSAC GPSDO solution has a vcxo-based noise filter pll on the pcb,
improving the noise performance and removing spurs as well over just the CSAC
by itself so the specs will be quite different.
In fact the LN CSAC version of that board achieves around -100dBc/Hz at one Hz,
ma
Hi Bob,
On 09/27/2013 01:44 PM, Bob Camp wrote:
> Hi
>
>
>
> Rise and fall times are not the thing to worry about on the gates. Look at
> the propagation delay. That's what will vary.
>
>
> On Sep 27, 2013, at 2:11 AM, Tom Minnis wrote:
>
>> Thanks for all your thoughts on the subject. Let me
On 09/27/2013 12:53 PM, Charles Steinmetz wrote:
> Tom wrote:
>
>> One of my first applications is to use a 10MHz output to phaselock a
>> VCXO master clock in a radio transceiver. * * * Next I went to
>> IDT to find the best logic buffer I could find. I am looking at the
>> IDT 74FCT38072
I checked Mini Circuits and they have 2 10MHz low Pass filters for
$8.95. I think I will try and lay out a discrete T band pass which can
easily be turned into a low pass if it gets too tweeky. This should be
less than $3. I think I can use a simple SPDT switch to option the
outputs for eith
Hi Tom,
yes, the GPSTCXO has a pretty good typical phase noise above 100Hz or so
for being "just" a TCXO, competitive to or even a bit better than some good
SC-cut OCXO's. Compare that to the Trimble Mini-T for example which has a
noise floor spec of only -145dBc/Hz according to the Trimbl
Hi
Two very conventional RF chokes (couple of uH each) and an NPO cap (couple
hundred pf) are all you really need for the square to sine filter. It's
probably a good idea to put a blocking cap on the thing as well. If you want to
get fancy, put a three resistor 6 db pad on it as well. That way
May be these links will be useful. TADD-3 Pulse-per-Second Distribution
Amplifier http://www.tapr.org/kits_tadd-3.html
TADD-1 RF Distribution Amplifier http://www.tapr.org/kits_tadd-1.html
--
Nick Medina
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I haven't even begun to look for video amps yet. I may not need one if
I filter an output of an high powered 5V buffer. What I hear is a
simple passive low pass filter will do. That being the case, I may put
them on all the outputs and make it a jumper option. The other project
brewing here
Hi
Rise and fall times are not the thing to worry about on the gates. Look at the
propagation delay. That's what will vary.
On Sep 27, 2013, at 2:11 AM, Tom Minnis wrote:
> Thanks for all your thoughts on the subject. Let me play back what I have
> learned and how it may apply to my chal
r some things, but I tend to avoid them like the
> plague, or immediately turn them to sine, unless I need them. It just depends
> what it's wanted for.
>
> Angus.
>
>
> From: "Bob Camp"
> To: "Discussion of precise time and frequency measurement"
Tom wrote:
One of my first applications is to use a 10MHz output to phaselock a
VCXO master clock in a radio transceiver. * * * Next I went
to IDT to find the best logic buffer I could find. I am looking at
the IDT 74FCT38072 2 channel clock driver for PPS. It can drive
about 50mA if
Hal,
> SN74LVC1G125 - Single Bus Buffer Gate with 3-State Output
TI does all of their testing: f = 10MHz for the chip - that is in the
datasheet.
If you drive it too hard, expect it to drive too much capacitance, etc -
yeah - the voltage waveform will suffer.
But, using it within the spec - I t
I assume you are driving 50 ohm coax with a 50 ohm series termination at the
driver and a 50 ohm terminator at the far end. That's 100 ohms or 50 mA at
5V.
The series terminator avoids junk if the far end isn't terminated and also
provides short circuit protection. It also cuts the voltage at
Tom,
OK - one question for now if that is OK - your video amp - is it base-band
or broadband?
Regards,
John W,
On Thu, Sep 26, 2013 at 11:11 PM, Tom Minnis wrote:
> Thanks for all your thoughts on the subject. Let me play back what I have
> learned and how it may apply to my challenge. One
Thanks for all your thoughts on the subject. Let me play back what I
have learned and how it may apply to my challenge. One of my first
applications is to use a 10MHz output to phaselock a VCXO master clock
in a radio transceiver. The VCXO is the Christek CVHD-950 which has a
noise floor of
:44 AM
Subject: Re: [time-nuts] Clock Driver Design
Hi
Ok, the SN74LVC1G125 is 35 cents each at Mouser if you buy at least 10 pieces.
That's going to be $3.50. LM78L05 is 26.5 cents if you buy 10 pcs. You will
need some bypass caps and resistors, I'd assume you already have them.
Say yo
Hi
Ok, the SN74LVC1G125 is 35 cents each at Mouser if you buy at least 10 pieces.
That's going to be $3.50. LM78L05 is 26.5 cents if you buy 10 pcs. You will
need some bypass caps and resistors, I'd assume you already have them.
Say you want 10 channels, that's 11 logic id's. At one IC per out
Bob,
Totally agree.
24mA of drive at 3.3V is pretty nice in a small footprint for the parts we
are discussing. Of course as you have pointed out you can drive them at 5V
too.
Mini-circuits is a good place to look too - especially for us hobbyists:
http://www.minicircuits.com/products/DesignerK
Hi
How clean is your clock source? If you have something that is -150 dbc at 1 Hz,
then you probably need some fancy analog gizmos. If you can make do with "only"
-110 to -120 dbc/Hz at 1 Hz, then properly driven LVC CMOS will do just fine.
That's true for a square or a sine output. Since you p
Tom,
If you are building your own board - I have used this part:
SN74LVC1G125 - Single Bus Buffer Gate with 3-State Output
and it is suitable for the job. I have measured the performance of the
logic family - and what I observed follows what is in the spec sheets from
TI. I did not officially
TV video distribution amps work very nicely. Even better if you open them
up and change the matching from 75ohm to 50. :)
Bob
On Thu, Sep 26, 2013 at 3:19 PM, Glenn Little WB4UIV <
glennmaill...@bellsouth.net> wrote:
> Would an analog video distribution amplifier work?
> These are available ch
Would an analog video distribution amplifier work?
These are available cheap.
TV stations used these eight or so in a frame.
The frame had a power supply and the BNC i/o connectors.
Each da would drive 6 or 8 outputs.
73
Glenn
WB4UIV
Retired TV CE.
At 01:28 PM 9/26/2013, you wrote:
I am looking
For low phase noise output at lower frequencies you should consider a
lambda divider feeding a low pass filter.
Although wideband opamps are convenient a discrete buffer amp can
produce a higher level output with lower additive phase noisee.
Bruce
Tom Minnis wrote:
I am looking into various de
I am looking into various degrees of craziness. The source is CMOS and
there are plenty of 1 in to N out parts designed to drive clocks on a
PCB but not much is said about driving clocks on to a random length of
coax to another piece of equipment and what additional precautions that
might warr
Hi
Standard high speed CMOS logic works pretty well. How crazy are you trying to
get?
Bob
On Sep 26, 2013, at 1:48 AM, Tom Minnis wrote:
> I am working on a small clock distributor and wanted to get some ideas on
> what works best for 10MHz and 1PPS driver circuits. I remember sifting
> th
I am working on a small clock distributor and wanted to get some ideas
on what works best for 10MHz and 1PPS driver circuits. I remember
sifting through the archives a year or so ago and tripped on some
discussion of this but I can't find it anymore.
Tom
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