Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

> > 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)

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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,

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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”

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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.

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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:

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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

[time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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:

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

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