measurement time-nuts@febo.com
Sent: Thursday, August 7, 2014 6:11 PM
Subject: Re: [time-nuts] Effects of noise on EFC line? - Resolved
Hi
Your EFC line is probably bypassed internally to the OCXO. A 3db modulation
bandwidth beyond 1 KHz is unlikely. A modulation bandwidth below 100 Hz
b...@evoria.net said:
So, I may throw another cap on it, but it seems to be clean down to what I
can measure at the OCXO on my old Tek 455 with an X10 probe.
Another thing to consider when chasing that sort of problem: How much are you
picking up with your scope probe and/or its ground wire?
Hi
Your EFC line is probably bypassed internally to the OCXO. A 3db modulation
bandwidth beyond 1 KHz is unlikely. A modulation bandwidth below 100 Hz is
quite possible.
Next thing to consider is that the EFC does FM on the OCXO. Phase noise is PM
modulation. FM is 1/Fmod relative to PM. If
he is on the right truck, just look around in your testing environment,
do you have shielded test set up, common ground for all the test gears ?
On 8/7/2014 3:58 PM, Hal Murray wrote:
b...@evoria.net said:
So, I may throw another cap on it, but it seems to be clean down to what I
can
of precise time and frequency measurement time-nuts@febo.com
Sent: Thursday, August 7, 2014 6:11 PM
Subject: Re: [time-nuts] Effects of noise on EFC line? - Resolved
Hi
Your EFC line is probably bypassed internally to the OCXO. A 3db modulation
bandwidth beyond 1 KHz is unlikely. A modulation
with an
X10 probe.
Bob
From: Bob Stewart b...@evoria.net
To: Time Nuts time-nuts@febo.com
Sent: Tuesday, August 5, 2014 1:36 PM
Subject: [time-nuts] Effects of noise on EFC line?
I've run into a noise problem on the EFC line of my GPSDO engine
I've run into a noise problem on the EFC line of my GPSDO engine at the
frequency of the oscillator. I've traced the source down to the 74HCT365 I'm
using to output the 1(or 5)MHz and 10MHz signals. When I pull it, the EFC
quietens down a lot. I'm seeing about 50mv of 10MHz noise at the
OK my 2 cents and others will have better comments.
You can use a far larger inductor in the efc line to try to reduce the
noise.
EFCs tend to be integrated by some cap. So they are slow moving compared to
the noise.
Better design is separate analog and digital supplies.
Regards
Paul
WB8TSL
On
I was able to quiet things down a lot by putting a 100 ohm resistor in
series with the 74HC output. If these guys drive more than a few inches of
wire, they ring like crazy. Also make sure you pay close attention to the
bypassing of the 5V supply. Make your bypass cap lead lengths as short as
On Tue, Aug 5, 2014 at 11:36 AM, Bob Stewart b...@evoria.net wrote:
I've considered switching the HCT out for a 74LS365, assuming my drive levels
are compatible. Unfortunately, I don't have one in stock, and I'm way out
of my pay grade, as they say. I've also thought about putting a 100uh
and use not to large capacity, because above the serial resonance
frequency [trace inductance, own inductance] it will be inductive!
73
Alex
KJ6UHN
On 8/5/2014 12:16 PM, Jim Harman wrote:
I was able to quiet things down a lot by putting a 100 ohm resistor in
series with the 74HC output. If
For EFC drive, I prefer to use a buffer fed from an analog power, so
that the power line noise is not as efficiently inserted into the EFC line.
Cheers,
Magnus
On 08/05/2014 10:00 PM, Chris Albertson wrote:
On Tue, Aug 5, 2014 at 11:36 AM, Bob Stewart b...@evoria.net wrote:
I've considered
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