Bob Camp wrote:
Hi
Ok, A bit more info:
1) Quadrature PLL using an RPD-1 DBM and a home brew lock box.
2) Willingness to accept that I'm measuring a pair of oscillators
3) Plenty of sources at the appropriate frequencies
4) First took a shot at this in 1975 (I forget the Fluke app note
Previously there was some confusion and disagreement on the subject.
What are the latest opinions?
The white noise which is the only dominant noise at higher frequencies
goes down into the lower range and do contribute to the ADEV measures
there, even if filtered.
Well, in which case
I'll take a guess at the answer.
White noise is constant power over Frequency
If the Nose Bandwidth is reduced from 100MHZ to 10 Hz then power would be
reduced by 1e7 to 1
Voltage is square root of Power so 1e7 power ratio is = 3e3 to 1 (1/3162)
The 10 ns noise would be reduced to 3ps
Or put
Gerhard Hoffmann wrote:
Bob Camp wrote:
Hi
Ok, A bit more info:
1) Quadrature PLL using an RPD-1 DBM and a home brew lock box. 2)
Willingness to accept that I'm measuring a pair of oscillators
3) Plenty of sources at the appropriate frequencies
4) First took a shot at this in 1975 (I forget
Gerhard Hoffmann wrote:
Bruce Griffiths wrote:
A preamp like that shown will be best suited to phase detectors with
low gain and output impedance with a resistive output termination
matched to the phase detector.
Phase detectors like the Minicircuits RPD-1, MPD-1 etc have a
relatively
Hi
Great screen shots showing phase noise measurement and just what the problem
is.
The top trace and the bottom trace show the same noise data. Different
frequency ranges are shown, but it's the same noise. The scale on the Y scale
on the traces shifts significantly between the two traces.
Hi
Don't forget that the output impedance of the mixer may also be changing with
changes in input level.
Lots of small things to check to make sure you have it all set up right.
Bob
On Feb 19, 2010, at 6:56 AM, Bruce Griffiths wrote:
Gerhard Hoffmann wrote:
Bruce Griffiths wrote:
A
Hi
A lot would depend on the phase noise of the source you were looking at.
Without amplification the 346 is going to drop -170 dbc/Hz noise onto a 10 dbm
source. Best guess is that you need 30 or 40 db more noise than that. As soon
as you start adding amps keeping things accurate gets
Bruce Griffiths wrote:
Not necessarily, it depends on the phase detector circuit details.
What phase detector output termination network did you use?
Aren't BF862's somewhat noisier than 2SK369's at low frequencies?
SRA-3H because I had them, 49R9 in series with 3n9 for sum termination.
LC
What advantage would one have using a higher gain antenna with a TBolt ?
Is it worth going in for a better antenna ?
Cheers
--
Raj, VU2ZAP
Bangalore, India.
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Hello Clay,
Joining in this discussion at a rather late stage - have you
considered using 74AC series gates as buffers? They provide reasonable
isolation and have surprisingly low phase noise.
A single 74AC04 inverter gives over 40dB reverse isolation at 10MHz, so
3 cascaded gates would give
Hi
Yup, that works.
A couple of *very* minor points:
-
My guess is that your output stage will be pulling a bit more than 15 ma.
This assumes you are running a 50 ohm load and a 50 ohm output impedance to
deliver 13 dbm (~ 2.5 V p-p).
More or less, 100 ohms from +5 to ground
In the Frequency Divider design I did back in 2008, I used 4 outputs from a
74AC541 in parallel for each output frequency, with a 180 ohm resistor in
series with each output. Unused inputs were of course tied to ground.
Output impedance of each driver in the '541 should be around 20-25 ohms, so
Message: 6
Date: Fri, 19 Feb 2010 15:17:44 -
From: Garry Thorp gth...@pascall.co.uk
Subject: Re: [time-nuts] Advice on 10 MHz isolation/distribution
Hello Clay,
Joining in this discussion at a rather late stage - have you
considered using 74AC series gates as buffers? They provide
Any opinions on the suitability of the TI OPA820 as a 10 MHz distribution amp?
The voltage noise is only 7 nV/rtHz @ 100 Hz (gain=2, I'll be using g=1), which
is the best I've seen so far for a wideband amp. Not as good as the discrete
transistor circuit, but it would use alot fewer parts.
Hi
As previously mentioned, these gizmos seem to all be spec'd out at 2V p-p
into 100 or 200 ohms. The only way to figure out what happens past that is
going to be to get one and see.
Bob
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf
Clay,
Analog devices AD4899-1 voltage noise = 2nV/rtHz @ 10Hz; GBW = 300MHz.
Pete Rawson
On Feb 19, 2010, at 12:05 PM, life speed wrote:
Any opinions on the suitability of the TI OPA820 as a 10 MHz distribution
amp? The voltage noise is only 7 nV/rtHz @ 100 Hz (gain=2, I'll be using
Hi All
I just acquired what I thought was an HP 58504A GPS antenna mounted inside
a 58510A housing/groundplane but it turns out that although the antenna is
very similar to the 58504A, both in shape and size, it's actually a
Mitsubishi antenna, model CCA532ST02.
A Google search tells me
Hi All,
I read Garry's email about using the 74AC04 as a distribution amplifier.
Did I read it right, does Gary say you will get -178 dBc/Hz at 10 kHz
offset???
Being one of only 3 or 4 companies in the world that manufactures
distribution amplifiers that break the -170 dBc/Hz region at 10
life speed wrote:
Message: 6
From: Pete Rawsonpeteraw...@earthlink.net
Subject: Re: [time-nuts] Advice on 10 MHz isolation/distribution
Clay,
Analog devices AD4899-1 voltage noise = 2nV/rtHz @ 10Hz; GBW = 300MHz.
Pete Rawson
That is an interesting part.
So, how does one think
Hi
. and thus if you drive it from a low impedance node you can get pretty
good isolation.
Bob
On Feb 19, 2010, at 5:59 PM, Bruce Griffiths wrote:
life speed wrote:
Message: 6
From: Pete Rawsonpeteraw...@earthlink.net
Subject: Re: [time-nuts] Advice on 10 MHz isolation/distribution
I picked up a used 10 Mhz distribution amplifier made by an English
company. The input uses a LT1016 10ns comparator as the input stage
that drives several CD74AC00E quad nand gates. The output from each
AC00 I.C. is fed through filters to recreate a pretty good sinewave.
Since the list members are familiar with lots of test equipment, I'd
like to ask what the folks here think about the HP 8590A Spectrum
Analyzer. Is this model ok? Are there any particular failures I should
be aware of in this 20+ year old equipment?
I have a chance to buy one locally. The only
If I can believe the simulation (a big if) the ADA4899-1 can provide 90 dB
isolation at 10 MHz, rolling up to 70 dB at 100 MHz, when configured with a
gain of +2
The subcircuit model provided by ADI is useless for noise, unfortunately. I
guess I'll have to build and measure, which I don't
From: Martyn Smith mar...@ptsyst.com
Subject: [time-nuts] Phase Noise of 74AC gates
I'm not about to say how we achieve -170 dBc/Hz phase noise, but we
definitely don't use op amps or logic gates!!
Regards
Martyn
Is this an advertisement? I don't think anybody believes a logic gate provides
This is a low performance economy model. It will be OK
for non-critical work. Regarding failures: it will be
difficult to get this repaired if it breaks.
Rick
N6RK
Joseph Gray wrote:
Since the list members are familiar with lots of test equipment, I'd
like to ask what the folks here think
Clay,
I would really like to have a copy of your test board for this effort.
I'm sure it will be a challenging layout. But it could be a very handy
piece of hardware. Supporting a PCA order would easy to do.
Pete Rawson
On Feb 19, 2010, at 6:17 PM, life speed wrote:
If I can believe the
life speed wrote:
If I can believe the simulation (a big if) the ADA4899-1 can provide 90 dB
isolation at 10 MHz, rolling up to 70 dB at 100 MHz, when configured with a
gain of +2
The subcircuit model provided by ADI is useless for noise, unfortunately. I
guess I'll have to build and
Martyn Smith wrote:
Hi All,
I read Garry's email about using the 74AC04 as a distribution amplifier.
Did I read it right, does Gary say you will get -178 dBc/Hz at 10 kHz
offset???
Being one of only 3 or 4 companies in the world that manufactures
distribution amplifiers that break the -170
Bruce Griffiths wrote:
He's made similar comments before.
It actually isnt that difficult to achieve an isolation amplifier phase
noise floor below -170dBc/Hz if one is careful to use appropriate parts,
design techniques, and the input signal level is high enough.
The real problem is
Arthur Dent wrote:
I picked up a used 10 Mhz distribution amplifier made by an English
company. The input uses a LT1016 10ns comparator as the input stage
that drives several CD74AC00E quad nand gates. The output from each
AC00 I.C. is fed through filters to recreate a pretty good sinewave.
Rick Karlquist wrote:
Bruce Griffiths wrote:
He's made similar comments before.
It actually isnt that difficult to achieve an isolation amplifier phase
noise floor below -170dBc/Hz if one is careful to use appropriate parts,
design techniques, and the input signal level is high enough.
The
Spend a little more, and get an HP 8560B or 8560E..
You will be much happier...
In a message dated 2/19/2010 16:39:17 Pacific Standard Time,
jg...@zianet.com writes:
Since the list members are familiar with lots of test equipment, I'd
like to ask what the folks here think about the HP
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