-requ...@febo.com wrote:
Message: 1
Date: Wed, 6 Nov 2013 19:40:31 -0800
From: John C. Westmoreland, P.E. j...@westmorelandengineering.com
To: Bob Stewart b...@evoria.net,Discussion of precise time and
frequency measurement time-nuts@febo.com
Subject: Re: [time-nuts] Trimble 34310-T EFC
of
my priorities list.
Bob
From: Dan Kemppainen d...@irtelemetrics.com
To: time-nuts@febo.com
Sent: Thursday, November 7, 2013 11:52 AM
Subject: Re: [time-nuts] Trimble 34310-T EFC Question
FYI, if you are measuring the voltage with a fluke or similar meters
Bob wrote:
I think I may need to change the LPF feeding the EFC in my GPSDO to
get rid of dithering jitter. Is there any point in adding a
resistor and cap in the EFC line, or do I need to go back and change
the values in the op-amp circuit feeding it? Currently an op-amp
directly feeds
Hi
…….unless the oscillator has a bias / attenuator network internally to shift
the region of the varicap’s capacitance/voltage curve the efc affects. That’s
often done to modify the linearity of the tuning curve.
It’s pretty simple to check. Put an ohm meter on it and see what it reads.
From: Charles Steinmetz csteinm...@yandex.com
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Thursday, November 7, 2013 5:09 AM
Subject: Re: [time-nuts] Trimble 34310-T EFC Question
Bob wrote:
I think I may need to change the LPF feeding the EFC in my
, 2013 6:27 AM
Subject: Re: [time-nuts] Trimble 34310-T EFC Question
Hi
…….unless the oscillator has a bias / attenuator network internally to shift
the region of the varicap’s capacitance/voltage curve the efc affects. That’s
often done to modify the linearity of the tuning curve.
It’s pretty
I think I may need to change the LPF feeding the EFC in my GPSDO to get rid of
dithering jitter. Is there any point in adding a resistor and cap in the EFC
line, or do I need to go back and change the values in the op-amp circuit
feeding it? Currently an op-amp directly feeds the EFC pin. I
Hello Bob,
If you think you are getting any high frequency into the EFC control - it
may be worth putting a(nother) low-pass filter in there. Are you measuring
noise on that line?
Do you have a snap-shot of a schematic? Or, can you take a picture of that
circuit? I would hazard a guess you
Bob,
Most EFC circuits are relatively high impedance, i.e., around 50K. So,
we are talking micro amps of current flow.
If there is jitter it is most likely somewhere else in the circuitry OR
you are seeing the natural noise in the GPS system.
BillWB6BNQ
Bob Stewart wrote:
I think
