Hi
Indeed, driving the device with a low noise (as in -175 dbc/Hz) OCXO does
produce the expected -172 dbc/Hz
output. Checking either with a power splitter ahead of the sine to square
conversion or splitting with logic gates
after the conversion yields a similar floor number. Close in noise is
Thanks, driving the input with a low PN OCXO is probably the difference, John
Miles used an HP8642 - not quite as low PN.
The PN test set is supposed to reject the source PN as it drives both inputs
of the PN test set. However this rejection isn't perfect.
I'll try driving a 74AC04 input
My point was that the PN performance of a device (eg OPA355) with largish
flicker noise can sometimes be a bit better than one might naively expect. The
OPA355's flicker voltage noise is 30dB worse than some wideband bipolar opamps.
Note: I don't recommend this particular fixed gain opamp for
Bruce wrote:
Such blanket statements aren't a particularly useful guide unless
calibrated by measurements.
* * *
The input voltage noise @1Hz can't be used directly to estimate the
PN noise at 1Hz offset.
My message referred readers to previous list messages for a more
detailed
Hi
To be very specific about the floor on the gates (as measured with a TimePod):
1) Clean 5.5V supply (max the part can rationally take).
2) Input signal L network transformed to just below the protection diode
threshold (roughly 6V p-p)
3) Input signal to the power splitter is from an OCXO so
> > AD8055 in non-inverting circuit with 1+2k7/2k7 gain has 9.6 nV/sqrt(Hz)
> > input-referred voltage noise PSD (if I calculated correctly..)
>
> With +10dBm input the corresponding SSB PN floor should be around
> -163dBc/Hz.
>
HI,
How is that calculated? I only get this far:
9.6nV/sqrt(Hz)
Anders wrote:
How is that calculated? I only get this far:
9.6nV/sqrt(Hz) into a 50R load is 1.8e-18 W/Hz or -147.3 dBm/Hz
what then?
As I said on Dec. 18 in response to the original post, the in-band
(10MHz) noise is NOT the main problem with respect to AM and PM
noise. The main problem
Such blanket statements aren't a particularly useful guide unless calibrated by
measurements. For example the OPA653 has a measured PN floor of around
-163dBc/Hz for a +13dBm input and the measured PN @1Hz offset is -150dBc/Hz
(comparable with the NIST isolation amps).However the voltage noise
Hi
To go through the whole deal a step at a time *assuming* that broadband noise
is the only issue:
-147 dbm noise per Hz
+10 dbm signal
=> -157 dbc / Hz
half to AM, half to PM
=> -160 dbc / Hz
ssb is already taken care of (noise on both sides if it’s broadband)
=> -160 dbc / Hz
Now,
Do those modern CMOS gates use deuterated wafers?I've not found any
measurements of the PN of modern CMOS gates.The measurements of devices like
the venerable 74AC04 indicate a PN floor around 10dBc/Hz worse than that.
Bruce
On Tuesday, 22 December 2015 3:00 PM, Bob Camp
Reverting somewhat closer to the original topic:Attached 2 BJT circuit has
unity gain with a PN floor well below -180dBc/Hz (10MHz +13dBm input) with a
reverse isolation better than 60dB. 2nd Harmonic output is about -70dBc or so.4
of these could be driven from the outputs of a 4 way splitter
In message <20151220042724.0f3d8406...@ip-64-139-1-69.sjc.megapath.net>, Hal
Murray writes:
>
>p...@phk.freebsd.dk said:
>> The main reason Ethernet went balanced was actually for fault isolation
>> (star-topology vs. bus) and signal quality (IT people were horrible at
>> "sharking" and
I once spent a very miserable but profitable weekend remaking a thin
ethernet network where the "installation expert" had stripped back 10B2
coax four inches and neatly separated core and shield, heatshrinked them
into pigtails and then soldered them into panel mount BNC sockets.
He was outraged
Tim,
There is two major strategies as you build a system and needs to figure
out how your ground bonding network (often just referred to bonding
network or grounding) should operate.
The isolation strategy says that the various equipments should only be
power grounded, as required for
Poul-Henning,
On 12/19/2015 03:58 PM, Poul-Henning Kamp wrote:
In message <56755ba1.7000...@rubidium.dyndns.org>, Magnus Danielson writes:
There is an over believe in isolation, as it only takes one mistake to
break the system. Another approach is to ground everything, cross-ground
Poul-Henning,
On 12/19/2015 10:11 PM, Poul-Henning Kamp wrote:
In message <56757344.2020...@rubidium.se>, Magnus Danielson writes:
The isolation strategy says that the various equipments should only be
power grounded, as required for personal safety, and then have all other
grounding
Hi
There is a very significant difference between coax and twisted pair when it
comes
to magnetic induction. The twist “cancels out” the signal on the pair. The
shield has
the signal induced on it’s outer surface. Transformers work better on twisted
pair than
on coax. If you look at a “normal”
In message <56757344.2020...@rubidium.se>, Magnus Danielson writes:
>The isolation strategy says that the various equipments should only be
>power grounded, as required for personal safety, and then have all other
>grounding paths "galvanically separated" (thus, DC and power
Li Ang wrote:
Hi Charles,
I'm making a 1-to-4 distribution amplifier for 10MHz. Can you give
any suggestion
The opamps I'm considering are LMH6609 LMH6624 LMH6702.
Does the piezoelectric effect of capacitors need to be considered here?
I'm working on a response to your questions. In the
p...@phk.freebsd.dk said:
> The main reason Ethernet went balanced was actually for fault isolation
> (star-topology vs. bus) and signal quality (IT people were horrible at
> "sharking" and crimping coax.)
The reason Ethernet switched to a star topology was to take advantage of the
wires that
Sat, Dec 19, 2015 09:18 AM
To: "Discussion of precise time and frequency
measurement"<time-nuts@febo.com>;
Subject: Re: [time-nuts] SMD TADD-1 distribution amplifier
Anders wrote:
>Far-out PN/AM is still 7dB short of the 6502!
>Looks like an SNR issue to me, rathe
In message <20151219095948.xmkoo...@smtp17.mail.yandex.net>, Charles Steinmetz
writes:
>There is a reason why some power transformers cost $385 and others
>with similar basic specs (voltage, current) cost $22.
For sensitive stuff I usually pick power supplies (of all kind)
which are
Chris wrote:
You are going to get at least a little circulating ground current because
of power supply parasitics
There is a reason why some power transformers cost $385 and others
with similar basic specs (voltage, current) cost $22. Properly
designed instruments, radios, medical and
Hi
The medical wall warts (at least the US ones) are a nice option. If you get
them from the importer, the cost adder is in the 20 to 30% range. The great
thing they do is to break the ground connection between the AC supply line and
the output
negative. It’s not a prefect solution, but it’s a
Transformer isolation isn't helping much at RF, as you will capacitively
couple through the transformer. I've been bitten by that in real life,
as I was called in to solve issues in someone elses design. It was only
when I introduced an RF choke that we got conducted noise battled. It's
also
>
>
>
>
>
>
> Thanks
> BI7LNQ
>
>
> -- Original --
> From: "Charles Steinmetz";<csteinm...@yandex.com>;
> Date: Sat, Dec 19, 2015 09:18 AM
> To: "Discussion of precise time and frequency
&
In message <56755ba1.7000...@rubidium.dyndns.org>, Magnus Danielson writes:
>There is an over believe in isolation, as it only takes one mistake to
>break the system. Another approach is to ground everything, cross-ground
>etc. and bring the DC/power-spurs down through conduction.
I think there is a valid heritage in transformer isolation in time and
frequency distribution, and it goes back to when telephone wiring was used
to distribute audio-type IRIG signals around a campus or other facility.
Even if a bunch of 60Hz or a local AM station was leaking through the IRIG
Hi
Another way to look at coax ….
You can (easily) have signals flowing on the *outside* of the shield. In an
ideal world with perfect coax outside would be
outside and inside inside. Ideally the two signal sets would never interact.
Once you put an isolated transformer on the end
of the
One of my other hats involves advising electronics scrap and
recycling companies, and the repair of all manner of electronics
equipment.
In all of the equipment I have rummaged through I can state the
following without reservation:
I have never seen any sign of damage caused by properly float
In message
, "Dr.
David Kirkby (Kirkby Microwave
Ltd)" writes:
I belive in the instant case Lead-Acid was used as a noise-free power
source rather than as backup.
>If do, I believe that the choice of a lead acid
In message <17836e4f4318bf8d2e5b6028224a0068.squir...@email.powweb.com>, "Chris
Caudle" writes:
>A better layout would be to have the power and input connectors on the
>same side of the PCB as the output connectors, and make provision for all
>of the connectors to be snugged down tight
one of the most important spec is the channel to channel separation. Do you
have done some measurements?
Luciano
www.timeok.it
On Thu 17/12/15 20:44 , Anders Wallin wrote:
> First prototype assembled today, tested with 12 VDC SMPS wall-wart supply
> and with 12
On 17 Dec 2015 21:00, "Anders Wallin" wrote:
>
> First prototype assembled today, tested with 12 VDC SMPS wall-wart supply
> and with 12 V lead-acid battery.
> Anders
Is the lead acid battery supposed to be there so the unit continues to
function if power is
When I used a Lead acid battery as a low noise and isolated power source I
raided the kitchen. Put the batter inside
a polyethylene container they type with a 'snap tight' lid. Then found in
my junk a nylon barb to threaded fitting and
some Tygon tubing to create an external vent. In another junk
On Fri, December 18, 2015 3:38 am, Poul-Henning Kamp wrote:
> A significant reason for the TADD-1 existing in the first place was to
> break groundloops. This is incompatible with tying all the BNC's
> together.
Assuming you mean power line frequency currents flowing between equipment,
the way
Poul-Henning wrote:
A significant reason for the TADD-1 existing in the first place was to
break groundloops. This is incompatible with tying all the BNC's together.
It is perfectly possible to ground coax connector bodies at RF
without grounding them at power-line frequencies (and expected
All the inputs and outputs were deliberately transformer isolated. Why
break the isolation by using capacitor from coax shield to chassis ground?
I do realize that some isolation transformers have "extra floating turns"
to give transformer action that cancels capacitive coupling. I don't think
Amp (now Tyco) did introduce them. Called "Decoupled Connectors'' Info at
http://www.te.com/usa-en/search.html?q=Decoupled%2BConnectors=header
Tyco parts 413476-2 and 5413476-2 are available from Mouser, maybe Digikey
as well
Cheers,
Dave M
Chris Caudle wrote:
On Fri, December 18, 2015
Hi
Well, if you are going to the angular ring microwave capacitors, you might as
well go to the
whole tubular filter approach to building the decoupling structure. The real
question is if 100 GHz
is a high enough frequency to consider or if you need to go higher….
Bob
> On Dec 18, 2015, at
On Friday, December 18, 2015 10:46:46 PM Anders Wallin wrote:
> Thanks for all the useful comments!
> Things improved quite a bit just by wrapping the (insulated) board in
> aluminium foil:
> http://www.anderswallin.net/wp-content/uploads/2015/12/alufoil_and_battery.p
> ng
>
> Op-Amps:
> Maybe it
On Friday, December 18, 2015 12:27:33 PM Charles Steinmetz wrote:
> Poul-Henning wrote:
> >A significant reason for the TADD-1 existing in the first place was to
> >break groundloops. This is incompatible with tying all the BNC's together.
>
> It is perfectly possible to ground coax connector
On Fri, December 18, 2015 4:50 pm, Bruce Griffiths wrote:
> On Friday, December 18, 2015 12:27:33 PM Charles Steinmetz wrote:
>> It is perfectly possible to ground coax connector bodies at RF
>> without grounding them at power-line frequencies
> Something like an annular ring capacitor that
All the inputs and outputs were deliberately transformer isolated. Why
break the isolation by using capacitor from coax shield to chassis ground?
I do realize that some isolation transformers have "extra floating turns"
to give transformer action that cancels stray capacitive coupling. I don't
Thanks for all the useful comments!
Things improved quite a bit just by wrapping the (insulated) board in
aluminium foil:
http://www.anderswallin.net/wp-content/uploads/2015/12/alufoil_and_battery.png
Op-Amps:
Maybe it wasn't clear enough on schematic, but I used the AD8055 (as in
TADD-1). The
Bruce wrote:
Something like an annular ring capacitor that insulates the BNC body from the
chassis whilst capacitively shorting it to the Chassis at RF ??.
Followed by a freeite sleeve/bead arround the connector body or the coax
connecting the signal from the connector to the PCB?
Back in the
On Fri, December 18, 2015 6:11 pm, Charles Steinmetz wrote:
> If you're careful with what goes on inside the box you won't
> *cause* any circulating ground current.
You are going to get at least a little circulating ground current because
of power supply parasitics, and for equipment running from
> Amp (now Tyco) did introduce them. Called "Decoupled Connectors'' Info at
> http://www.te.com/usa-
> en/search.html?q=Decoupled%2BConnectors=header
>
> Tyco parts 413476-2 and 5413476-2 are available from Mouser, maybe Digikey
> as well
>
And you might notice that the TimePod itself doesn't
Tim wrote:
All the inputs and outputs were deliberately transformer isolated. Why
break the isolation by using capacitor from coax shield to chassis ground?
You're trying to keep external RF from getting into the enclosure on
the shields. The outputs are still galvanically isolated.
Best
Anders wrote:
Far-out PN/AM is still 7dB short of the 6502!
Looks like an SNR issue to me, rather than some issue with the linear
regulator noise feeding through?!
AD8055 in non-inverting circuit with 1+2k7/2k7 gain has 9.6 nV/sqrt(Hz)
input-referred voltage noise PSD (if I calculated
First prototype assembled today, tested with 12 VDC SMPS wall-wart supply
and with 12 V lead-acid battery.
Compared against a SRS FS710 and a Symmetricom 6502 and John Ackermann's
2007 plot:
http://www.anderswallin.net/2015/12/frequency-distribution-amplifier-first-tests/
What does the 6502 do
That noise could come also from the environment, even trough ground-loop
with the cox cable [ if the cable is connected between two grounds and
the cable is long enough it will pick up noise since the noise-current
generates voltage drop along the cable's shield, but the same field does
not
In message
, Anders
Wallin writes:
>My 'ultra-low-noise DC-supply' in the form of a lead-acid battery improves
>things somewhat, but some spurs still remain:
Those spurs are reminiscent of what happens when you lift the ground of a coax
cable at one end and turn it into an antenna, in my experience. It is almost
always a bad idea to do this. Try shorting out the capacitor(s) at your input
and output jacks.
-- john, KE5FX
Miles Design LLC
> My
Anders,
the TL071 is not the right choice as it has a unity gain bandwidth of
only 3MHz! You should use an OP with a unity gain bandwidth of ten times
the wanted frequency at least (I guess 10MHz, so a 100MHz OP). Modern
OPs are AD8045 (preferable), AD8099 (too fast and too good for this
On Thu, December 17, 2015 3:47 pm, John Miles wrote:
> Those spurs are reminiscent of what happens when you lift the ground of a
> coax cable at one end and turn it into an antenna, in my experience.
This came up several weeks ago, I don't remember whether an original
TADD-1 or some other
Also add
1) BNX002
(attenuates noise in 1MHz to 1GHZ region) between the dc input and the input to:
2) Simple LCR filter - attenuates from 10kHz to 10MHz (see attachment)
Output of which is connected to the regulator input.
3) Like all the so called RF regulators with internal low pass filters
Hi
Somethings to consider:
How quiet are the sources you will be running through this amplifier?
How predictable are the levels of the sources?
How important is isolation?
Do you need lowpass / bandpass filtering (are there other RF sources running
around?)?
Is ESD on the coax an issue
HI all,
I need to build a few distribution amplifiers (>90% for 10MHz, sometimes
maybe 5MHz) and instead of reinventing the wheel I decided to try to
modernize the TADD-1 into an all (almost) SMD design. Here are some draft
sketches:
Anders
U101 only needs to have a gain of 1 at dc so replace R104 and R105 with a
capacitor connected to ground.
Adjust the other components of the gain determining network accordingly.Also
the junction of the power supply divider R102 and R103 should be heavily
capacitively bypassed to ground
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