Re: [time-nuts] high rev isolation amps

[Charles Steinmetz]

Rick wrote:

If only this were true.  Authors at NIST have consistently told me 
that the conditions of working for the government preclude them from 
mentioning the names of vendors.  Thus you get generic JEDEC 
transistor numbers.  Along with the fact that JEDEC numbers are 
useless concerning unspecified parameters, it tends to make NIST 
designs non-reproducible.


It's often much worse than that.  NBS/NIST tends to require new 
designs to be compatible with existing equipment crates and frames, 
so designs are routinely compromised by legacy form factors, 
technologies, power supply availabilities, and other considerations 
that preclude building the best widget they know how to 
design.  (There are some other contributing factors, as well.)  You 
might think NIST wouldn't settle for anything less than the best they 
can do, but in fact "good enough" often rules the day.


can you please let the group in on the actual vendors and part 
numbers of the new era transistors accidentally having low flicker noise?


Zetex (Diodes, Inc) pioneered this new technology.  There was some 
discussion on the list last summer (see, for example, 
). 
There are also some discussions in the volt-nuts list archives.


I (and others) discovered these parts back in the '90s and have been 
using them "off label" for ultra-low voltage noise designs for 20-odd 
years.  Then, the 3rd Edition of Horowitz and Hill's "The Art of 
Electronics" made it public knowledge.  (Speaking of which, Chapter 8 
is absolutely essential reading for anyone who even pretends to be 
designing low noise circuits.)


Best regards,

Charles


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Re: [time-nuts] high rev isolation amps

[Richard (Rick) Karlquist]

On 3/30/2016 8:18 AM, Tim Shoppa wrote:



There's a real beauty to many of the NIST designs - using topology and
jellybean parts to achieve the performance, rather than selected devices.

Tim N3QE




If only this were true.  Authors at NIST have consistently told me
that the conditions of working for the government preclude them from
mentioning the names of vendors.  Thus you get generic JEDEC transistor
numbers.  Along with the fact that JEDEC numbers are useless concerning
unspecified parameters, it tends to make NIST designs non-reproducible.
Not arguing that they didn't really get whatever results they present.

My understanding is that "CATV" transistors are all derived originally
from the 2N3866, FWIW.

Special request to Charles Steinmetz:  can you please let the group in
on the actual vendors and part numbers of the new era transistors 
accidentally having low flicker noise?  Many thanks!


Rick N6RK
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Re: [time-nuts] high rev isolation amps

[Charles Steinmetz]

Poul-Henning  wrote:

I would have expected them to use capacitance optimized transistors, 
also known as UHF transistors ?   Something like BFQ19 maybe ?


One of the main problems in isolation (and distribution) amplifiers 
is excessive additive (historically called "residual") phase noise 
due to AM to PM conversion in the amplifier.  The worst AM noise 
turns out to be flicker noise (1/f noise) in the transistors at 
baseband frequencies.  RF transistors typically have much higher 
flicker noise (by orders of magnitude), including 1/f corner 
frequencies that are decades higher, than general-purpose 
transistors.  The fact that most of the converted PM noise is at 1/f 
frequencies is doubly insidious, because it is close in to the 
carrier (and, therefore, essentially impossible to remove by filtering).


So, the best transistors for low phase noise design (of both 
amplifiers and oscillators) are transistors that have low flicker 
noise and low 1/f corners -- consistent, of course, with having 
sufficient gain at the RF frequencies of interest.  These days, there 
is a whole new class of BJTs that were designed for high current 
density and very low saturation voltage, some of which have 
astonishingly low flicker noise and also good gain-bandwidth products 
(f-sub-Ts).  Today's low phase noise designs often take advantage of 
these "accidental" characteristics of the new transistors.


Best regards,

Charles


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Re: [time-nuts] high rev isolation amps

[Tim Shoppa]

I usually call those "CATV transistors" :-). 2N5109 etc. They also have
very reasonable power dissipations and despite being "UHF transistors" they
are most commonly used today in low-frequency work where high IP3 is
crucial.

That said, it is possible that going to multiple consecutive common-base
stages with jellybean transistors, is good enough, that layout and
packaging become more important than using specialized transistors.

There's a real beauty to many of the NIST designs - using topology and
jellybean parts to achieve the performance, rather than selected devices.

Tim N3QE

On Wed, Mar 30, 2016 at 2:28 AM, Poul-Henning Kamp 
wrote:

> 
> In message , Bob Camp
> writes:
>
> >There were (and maybe still are) SOT-89 versions of the 2N3804 and
> >3906. They will handle more power than most of the other versions.
> >That gives you better Vce on the string. They also have less
>
> Stupid question:  I would have expected them to use capacitance
> optimized transistors, also known as UHF transistors ?
>
> Something like BFQ19 maybe ?
>
> --
> Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
> p...@freebsd.org | TCP/IP since RFC 956
> FreeBSD committer   | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] high rev isolation amps

[Poul-Henning Kamp]

In message , Bob Camp writes:

>There were (and maybe still are) SOT-89 versions of the 2N3804 and
>3906. They will handle more power than most of the other versions.
>That gives you better Vce on the string. They also have less

Stupid question:  I would have expected them to use capacitance
optimized transistors, also known as UHF transistors ?

Something like BFQ19 maybe ?

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
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Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] high rev isolation amps

[Charles Steinmetz]

Bob wrote:

There were (and maybe still are) SOT-89 versions of the 2N3804 and 
3906. They will handle more power than most of the other versions. 
That gives you better Vce on the string.


Bruce wrote:


The PZT3904 and PZT3906 are still available.


With most of these old circuits reducing the LF noise contribution 
to the emitter/collector current by the biasing circuit by utilising 
lower noise power supplies and/or using improved biasing methods can 
improve the clse in PN significantly.


The lower transistors on the totem pole operate in current mode and 
typically have only 3-5v from C to E, so their dissipation is very 
low even if the standing current is high.  I used TO-92 and SOT-23 
transistors there.  The top transistor, which must develop the output 
voltage, dissipates more than a TO-92 or SOT-23 should be asked to 
handle, even with a good heatsink, so I typically used TO-5 (TO-39) 
or SOT-89 transistors (with heatsinks) there.


It is definitely true that the published NIST designs did not 
minimize circuit noise.  I used *much* larger base bypass capacitors, 
and improved capacitance multipliers.  I also used separate 
capacitance multipliers for the base divider string and the collector 
supply.  I played with ultra-low-noise DC regulators on each base and 
for the collector supply, which gave modest improvements in both 
noise and distortion -- but the added complexity was not justified by 
the gains, IMO.  I did find that doing without the interstage 
resistors (from the collector of one transistor to the emitter of the 
next higher transistor) reduced both noise (modestly) and distortion 
(slightly).  In the very rare cases when a circuit oscillated (I 
experimented with *many* combinations of transistors), I used ferrite 
beads in place of the resistors or on one or more of the base 
leads.  Choosing transistors with very low base spreading resistance 
was another key to lowering noise.


Best regards,

Charles


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Re: [time-nuts] high rev isolation amps

[Bruce Griffiths]

Using a higher dissipation transistor package for the output stage is also the 
strategy adopted in some commercial versions of these amplifiers. 
Note that the amplifier with the 4:1 (turns ratio) output transformer and 300 
ohm resistor in series with the primary of the input transformer is intended to 
have its input connected in parallel with 5 others to form a 6 output 
distribution amplifier.
If it is redesigned for a 50 ohm input with a 2: (turns ratio) output 
transformer the PN floor is reduced significantly.
The biggest drawback for some applications is the 24-28V power supply.A 12V or 
lower voltage supply would be nice.This can only be achieved (without unduly 
raising the amplifier PN floor) by something like a folded cascade of NPN + PNP 
+ NPN CB stages or by transformer coupling between stages. Using a CB input 
stage has the advantage that the input signal voltage swing doesn't reduce the 
available collector voltage swing as much as in a CE stage. 

Bruce
 

  From: Charles Steinmetz 
 To: Discussion of precise time and frequency measurement  
 Sent: Wednesday, 30 March 2016 5:51 PM
 Subject: Re: [time-nuts] high rev isolation amps
   
Bob wrote:

>There were (and maybe still are) SOT-89 versions of the 2N3804 and 
>3906. They will handle more power than most of the other versions. 
>That gives you better Vce on the string.

Bruce wrote:

>The PZT3904 and PZT3906 are still available.

>With most of these old circuits reducing the LF noise contribution 
>to the emitter/collector current by the biasing circuit by utilising 
>lower noise power supplies and/or using improved biasing methods can 
>improve the clse in PN significantly.

The lower transistors on the totem pole operate in current mode and 
typically have only 3-5v from C to E, so their dissipation is very 
low even if the standing current is high.  I used TO-92 and SOT-23 
transistors there.  The top transistor, which must develop the output 
voltage, dissipates more than a TO-92 or SOT-23 should be asked to 
handle, even with a good heatsink, so I typically used TO-5 (TO-39) 
or SOT-89 transistors (with heatsinks) there.

It is definitely true that the published NIST designs did not 
minimize circuit noise.  I used *much* larger base bypass capacitors, 
and improved capacitance multipliers.  I also used separate 
capacitance multipliers for the base divider string and the collector 
supply.  I played with ultra-low-noise DC regulators on each base and 
for the collector supply, which gave modest improvements in both 
noise and distortion -- but the added complexity was not justified by 
the gains, IMO.  I did find that doing without the interstage 
resistors (from the collector of one transistor to the emitter of the 
next higher transistor) reduced both noise (modestly) and distortion 
(slightly).  In the very rare cases when a circuit oscillated (I 
experimented with *many* combinations of transistors), I used ferrite 
beads in place of the resistors or on one or more of the base 
leads.  Choosing transistors with very low base spreading resistance 
was another key to lowering noise.

Best regards,

Charles


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Re: [time-nuts] high rev isolation amps

[Bruce Griffiths]

With most of these old circuits reducing the LF noise contribution to the 
emitter/collector current by the biasing circuit by utilising lower noise power 
supplies and/or using improved biasing methods can improve the clse in PN 
significantly.
The PZT3904 and PZT3906 are still available.
Bruce
 

On Wednesday, 30 March 2016 1:00 PM, Bob Camp  wrote:
 

 Hi

There were (and maybe still are) SOT-89 versions of the 2N3804 and 3906. They 
will handle more
power than most of the other versions. That gives you better Vce on the string. 
They also have less
package inductance which helps tie the base to ground. If you are building some 
of those circuits, they
are worth looking for.

Bob

> On Mar 29, 2016, at 6:47 AM, Charles Steinmetz  wrote:
> 
> See below for schematics of the NIST isolation amplifiers from 1990 and 1997. 
>  NIST reported the isolation as >120dB.
> 
> I built isolation amplifiers similar to these (with lower-noise power 
> supplies and biasing tinkered slightly for better dynamic range), and with 
> careful construction achieved isolation substantially better than 120dB (see 
> my post of 11/25/14 for more details).
> 
> Best regards,
> 
> Charles
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Re: [time-nuts] high rev isolation amps

[Bob Camp]

Hi

There were (and maybe still are) SOT-89 versions of the 2N3804 and 3906. They 
will handle more
power than most of the other versions. That gives you better Vce on the string. 
They also have less
package inductance which helps tie the base to ground. If you are building some 
of those circuits, they
are worth looking for.

Bob

> On Mar 29, 2016, at 6:47 AM, Charles Steinmetz  wrote:
> 
> See below for schematics of the NIST isolation amplifiers from 1990 and 1997. 
>  NIST reported the isolation as >120dB.
> 
> I built isolation amplifiers similar to these (with lower-noise power 
> supplies and biasing tinkered slightly for better dynamic range), and with 
> careful construction achieved isolation substantially better than 120dB (see 
> my post of 11/25/14 for more details).
> 
> Best regards,
> 
> Charles
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Re: [time-nuts] high rev isolation amps

[Charles Steinmetz]

See below for schematics of the NIST isolation amplifiers from 1990 
and 1997.  NIST reported the isolation as >120dB.


I built isolation amplifiers similar to these (with lower-noise power 
supplies and biasing tinkered slightly for better dynamic range), and 
with careful construction achieved isolation substantially better 
than 120dB (see my post of 11/25/14 for more details).


Best regards,

Charles
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Re: [time-nuts] high rev isolation amps

[Magnus Danielson]

Hi John,

This would indeed be interesting.

I would assume that one would like to have shielded boxes for these.

Cheers,
Magnus

On 03/27/2016 04:33 AM, John Ackermann N8UR wrote:

In light of this discussion, I'm taking a deep gulp to mention a project
that's finished but has been on my back burner for a while.

A few years ago I laid out a high isolation, low noise buffer amp based
on one of Bruce's cascaded-transistor designs.  Isolation was measured
in excess of 100dB with PN floor around -170dBc/Hz.  The frequency range
is 1 MHz to 30 MHz and gain can be set from -10 to +7 dB.  It's designed
for 18VDC input but will work at 13.8, with less headroom.  At 18V it
can put out close to +20dBm.  It's a 1.75 x 3.75 inch board using SMT
parts (nothing tiny, but *lots* of passives -- about 80 parts total).

The board is ready to go, but I wasn't sure if there would be enough
interest to justify production.  Given the tedious surface mount
assembly, I assumed that there wouldn't be much interest in a kit, and
an assembly run requires at least 50, and preferably 100, units to get a
reasonable price.  At 100 units, I hope the price for an assembled board
could be below $100, but no guarantees.

If there is enough interest, TAPR could consider doing a production run.
  If not, I'll release the design package including Gerbers.

I'll try to get some better documentation put together in the next week
or two, and figure out a way to create a sign-up list for people who are
interested.  We'd have to have a minimum number of committed orders
before kicking things off.

John


On 03/26/2016 08:24 PM, jimlux wrote:

On 3/26/16 4:14 PM, Richard (Rick) Karlquist wrote:

Nothing has come to my attention in the last
35 years that is superior for buffer amplifiers
to the simple cascade of grounded base transistors
as described by numerous NBS/NIST papers.
The chain usually starts with a common emitter
(with emitter degeneration resistor), which
is an even older NBS classic.

I realize you asked for an OTS connectorized
version.  Unfortunately, I have never seen
one of these offered in said 35 years.


Yeah, i've spent a while looking through various catalogs..

Odd that nobody sells one: sure, it's probably a limited market, but
there's plenty of companies that sell limited market widgets (e.g. I'm
surprised Wenzel doesn't sell one.. in the online catalog info, they
don't even give S12 data of any kind)




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Re: [time-nuts] high rev isolation amps

[jimlux]

On 3/27/16 4:40 AM, Dr. David Kirkby (Kirkby Microwave Ltd) wrote:

On 27 Mar 2016 03:00, "jimlux"  wrote:


On 3/26/16 3:25 PM, Bruce Griffiths wrote:


On Saturday, March 26, 2016 09:30:30 PM Rob Sherwood. wrote:


You cannot add the directivity and gain.  Doesn't work that way.  Rob,

NC0B.


Sent from my iPad


Minicircuits would disagree with that and its their amplifier.

Bruce





Well, it's a bit inconsistent between gain, directivity and S parameters.

at 5.4 MHz the ZFL-500LN has the following S parameters @ 15 V in the

.s2p file (there's two units' measurements in the files)


S11 -35.5, -32.1
S21  29.7,  29.5
S12 -47.5,- 47.2
S22 -39.5, -28.3

On the other hand, the data sheet "typical data" says: at 5.4MHz 27.9 dB

gain, 26.5 dB directivity, which Minicircuits defines as isolation-gain
(implying isolation is 54.4)

http://www.minicircuits.com/pdfs/ZFL-500LN.pdf


I think you are wrong there. From the Touchstone .s2p data you give above:

Isolation (dB) = - |S12|=+47.5 dB.

Gain (dB) = |S21|=+29.7 dB.


Yes, that's what I would think: roughly 29 dB gain, roughly 47 dB 
reverse isolation... BUT, that's nothing like what the data sheet says.






Directivity, a term I can't say that I have seen much applied to amplifiers
other than by Minicircuits,  is according to the Minicircuits definition,
the difference between isolation and gain. But I don't see a note of
whether its gain - isolation or isolation-gain.


I just assumed it's whichever has the positive sign, since the published 
numbers are positive: so isolation-gain..



  Assuming the latter, the

directivity would be

47.5-28.7=18.8 dB.




That doesn't agree with your result,  nor does it agree with the
Minicircuits typical value of 26.5 dB.
I was using the data sheet numbers for gain/directivity and working 
backwards to a reverse isolation.






But the Minicircuits typical gain in the data sheet is 27.94 dB.

I learned from a Minicrcuits sales rep that the "typical" data in their
data sheets is the result of one device taken randomly from the production
line. It is not any sort of average. I find that very odd, and so did the
sales rep, but I was told that was true.


I'm not surprised at all.  And it's obvious that the data sheet number 
doesn't happen to match either of the two devices they provide as 
S-parameter data.





I think it is time to confirm these numbers with Minicircuits,  but I would
not rely on "typical" data if you want a guaranteed isolation.


Maybe there's some sort of assumption about source/load impedance (e.g.

not necessarily perfect 50 ohms)

I doubt that is so. S-parameters by definition assume that all other ports
are terminated in devices which reflect no power at the system impedance.
In the case of most devices that's 50 Ohm loads, but in the case of mixed
waveguide/coaxial devices waveguide loads would be used.


Yes about the S parameters.. I was wondering if the "gain" and 
"isolation" numbers made some other assumptions..





Minicircuits do a range of high isolation amplifiers.  I assume that they
guarantee figures for those although I have not checked.



The ZFL-500LN is one of the high isolation amps (I searched for 
isolation>40dB to get the list.


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Re: [time-nuts] high rev isolation amps

[Dr. David Kirkby (Kirkby Microwave Ltd)]

On 27 Mar 2016 03:00, "jimlux"  wrote:
>
> On 3/26/16 3:25 PM, Bruce Griffiths wrote:
>>
>> On Saturday, March 26, 2016 09:30:30 PM Rob Sherwood. wrote:
>>>
>>> You cannot add the directivity and gain.  Doesn't work that way.  Rob,
NC0B.
>>>
>>> Sent from my iPad
>>
>> Minicircuits would disagree with that and its their amplifier.
>>
>> Bruce
>>>
>>>
>
> Well, it's a bit inconsistent between gain, directivity and S parameters.
>
> at 5.4 MHz the ZFL-500LN has the following S parameters @ 15 V in the
.s2p file (there's two units' measurements in the files)
>
> S11 -35.5, -32.1
> S21  29.7,  29.5
> S12 -47.5,- 47.2
> S22 -39.5, -28.3
>
> On the other hand, the data sheet "typical data" says: at 5.4MHz 27.9 dB
gain, 26.5 dB directivity, which Minicircuits defines as isolation-gain
(implying isolation is 54.4)
> http://www.minicircuits.com/pdfs/ZFL-500LN.pdf

I think you are wrong there. From the Touchstone .s2p data you give above:

Isolation (dB) = - |S12|=+47.5 dB.

Gain (dB) = |S21|=+29.7 dB.

Directivity, a term I can't say that I have seen much applied to amplifiers
other than by Minicircuits,  is according to the Minicircuits definition,
the difference between isolation and gain. But I don't see a note of
whether its gain - isolation or isolation-gain.Assuming the latter, the
directivity would be

47.5-28.7=18.8 dB.

That doesn't agree with your result,  nor does it agree with the
Minicircuits typical value of 26.5 dB.

But the Minicircuits typical gain in the data sheet is 27.94 dB.

I learned from a Minicrcuits sales rep that the "typical" data in their
data sheets is the result of one device taken randomly from the production
line. It is not any sort of average. I find that very odd, and so did the
sales rep, but I was told that was true.

I think it is time to confirm these numbers with Minicircuits,  but I would
not rely on "typical" data if you want a guaranteed isolation.

> Maybe there's some sort of assumption about source/load impedance (e.g.
not necessarily perfect 50 ohms)

I doubt that is so. S-parameters by definition assume that all other ports
are terminated in devices which reflect no power at the system impedance.
In the case of most devices that's 50 Ohm loads, but in the case of mixed
waveguide/coaxial devices waveguide loads would be used.

Minicircuits do a range of high isolation amplifiers.  I assume that they
guarantee figures for those although I have not checked.

Dave
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Re: [time-nuts] high rev isolation amps

[Poul-Henning Kamp]

In message <56f74668.1010...@febo.com>, John Ackermann N8UR writes:

>I'll try to get some better documentation put together in the next week 
>or two, and figure out a way to create a sign-up list for people who are 
>interested.  We'd have to have a minimum number of committed orders 
>before kicking things off.

Yes, please!


-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
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Re: [time-nuts] high rev isolation amps

[Herbert Poetzl]

On Sat, Mar 26, 2016 at 10:33:12PM -0400, John Ackermann N8UR wrote:

> If there is enough interest, TAPR could consider doing a
> production run.

> If not, I'll release the design package including Gerbers.

I'd be very interested in the design files, i.e.
schematic and gerbers regardless of the TAPR
production run.

> I'll try to get some better documentation put together in the
> next week or two, and figure out a way to create a sign-up list
> for people who are interested. We'd have to have a minimum
> number of committed orders before kicking things off.

Thanks in advance,
Herbert

> John
> 

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Re: [time-nuts] high rev isolation amps

[John Ackermann N8UR]

When I looked at the Wenzel amps, they were extremely low noise, but the 
isolation was nothing to write home about.


On 03/26/2016 08:20 PM, John Miles wrote:



I'm looking for off the shelf connectorized amplifiers with very good
reverse isolation for doing things like intermod measurements (e.g. 2
signal generators followed by amps/pads into a combiner) and phase noise
measurements for a digital receiver.

1-100 MHz kind of frequency range..

I've used ZFL-500LN (30dB gain, 27 dB directivity in the data sheet,
which I interpret as 57dB reverse) , ZX60-4016 (really more of a
microwave amp, and not so hot reverse wise.. 25 dB)

I'm not particularly cost constrained, so a higher power amp (which also
reduces distortion products from the amp) followed by pads is always an
alternative.


Lots of options at http://www.spectradynamics.com, also see the LNDA series at 
http://www.wenzel.com.

-- john, KE5FX
Miles Design LLC

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Re: [time-nuts] high rev isolation amps

[John Ackermann N8UR]

In light of this discussion, I'm taking a deep gulp to mention a project 
that's finished but has been on my back burner for a while.


A few years ago I laid out a high isolation, low noise buffer amp based 
on one of Bruce's cascaded-transistor designs.  Isolation was measured 
in excess of 100dB with PN floor around -170dBc/Hz.  The frequency range 
is 1 MHz to 30 MHz and gain can be set from -10 to +7 dB.  It's designed 
for 18VDC input but will work at 13.8, with less headroom.  At 18V it 
can put out close to +20dBm.  It's a 1.75 x 3.75 inch board using SMT 
parts (nothing tiny, but *lots* of passives -- about 80 parts total).


The board is ready to go, but I wasn't sure if there would be enough 
interest to justify production.  Given the tedious surface mount 
assembly, I assumed that there wouldn't be much interest in a kit, and 
an assembly run requires at least 50, and preferably 100, units to get a 
reasonable price.  At 100 units, I hope the price for an assembled board 
could be below $100, but no guarantees.


If there is enough interest, TAPR could consider doing a production run. 
 If not, I'll release the design package including Gerbers.


I'll try to get some better documentation put together in the next week 
or two, and figure out a way to create a sign-up list for people who are 
interested.  We'd have to have a minimum number of committed orders 
before kicking things off.


John


On 03/26/2016 08:24 PM, jimlux wrote:

On 3/26/16 4:14 PM, Richard (Rick) Karlquist wrote:

Nothing has come to my attention in the last
35 years that is superior for buffer amplifiers
to the simple cascade of grounded base transistors
as described by numerous NBS/NIST papers.
The chain usually starts with a common emitter
(with emitter degeneration resistor), which
is an even older NBS classic.

I realize you asked for an OTS connectorized
version.  Unfortunately, I have never seen
one of these offered in said 35 years.


Yeah, i've spent a while looking through various catalogs..

Odd that nobody sells one: sure, it's probably a limited market, but
there's plenty of companies that sell limited market widgets (e.g. I'm
surprised Wenzel doesn't sell one.. in the online catalog info, they
don't even give S12 data of any kind)




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Re: [time-nuts] high rev isolation amps

[Rob Sherwood .]

If you ask Mini-Circuits about the details of their amps that are specified as 
to having high reverse isolation, they have a pad in the circuit. I don't know 
whether it is in the input or the output.  Maybe both, looking at a ZFL-2AD 
specs. 

>From a Mini-Circuits data sheet it says: active directivity (dB) = isolation 
>(dB) - gain (dB) 

Rob
NC0B

Sent from my iPad

> On Mar 26, 2016, at 6:00 PM, "Bruce Griffiths"  
> wrote:
> 
> 
> 
>> On Saturday, March 26, 2016 09:30:30 PM Rob Sherwood. wrote:
>> You cannot add the directivity and gain.  Doesn't work that way.  Rob, NC0B.
>> 
>> Sent from my iPad
> Minicircuits would disagree with that and its their amplifier.
> 
> Bruce
>> 
>>> On Mar 26, 2016, at 2:00 PM, "jimlux"  wrote:
>>> 
>>> 
>>> 
>>> Consulting the time-nuts hive mind here..
>>> 
>>> I'm looking for off the shelf connectorized amplifiers with very good
>>> reverse isolation for doing things like intermod measurements (e.g. 2
>>> signal generators followed by amps/pads into a combiner) and phase noise
>>> measurements for a digital receiver.
>>> 
>>> 1-100 MHz kind of frequency range..
>>> 
>>> I've used ZFL-500LN (30dB gain, 27 dB directivity in the data sheet, which
>>> I interpret as 57dB reverse) , ZX60-4016 (really more of a microwave amp,
>>> and not so hot reverse wise.. 25 dB)
>>> 
>>> I'm not particularly cost constrained, so a higher power amp (which also
>>> reduces distortion products from the amp) followed by pads is always an
>>> alternative. ___
>>> time-nuts mailing list -- time-nuts@febo.com
>>> To unsubscribe, go to
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>>> instructions there.
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>>> 
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Re: [time-nuts] high rev isolation amps

[Rob Sherwood .]

I use two ZHL-32A buffer amps, the appropriate Mini-Circuits LPFs, and 20 dB 
pads into a 4-way Mini-Circuits combiner. I believe it is ports 2&3 that have 
even better isolation than a 2-way combiner.  These buffer amps run on 24 
volts, where the ZFL-500LN doesn't have the output capability to test 100+ dB 
radios.  Some tests need a third signal source and complimentary buffer amp and 
associated items. 

To test a K3S or an IC-7851, it also requires HP 8642A generators that have 
lower phase noise than these top of the line rigs.  Even my 8662A generators 
are not good enough, though they were 5 years ago.  Now add the Flex 6700 and 
the ANAN-200D, the RMDR performance of a hand full of rigs is amazing. 

Unfortunately transmitter performance has not kept pace with receiver 
improvement. 

It will be interesting to test the new IC-7300 DSR with knobs (and lots of 
menus). 

Rob
NC0B

Sent from my iPad

> On Mar 26, 2016, at 6:00 PM, "jimlux"  wrote:
> 
> 
> 
>> On 3/26/16 2:30 PM, Rob Sherwood. wrote:
>> You cannot add the directivity and gain.  Doesn't work that way.  Rob, NC0B.
>> 
> 
> Yeah, I kind of figured that after getting the S parameters from minicircuits.
> 
>> Sent from my iPad
>> 
>>> On Mar 26, 2016, at 2:00 PM, "jimlux"  wrote:
>>> 
>>> 
>>> 
>>> Consulting the time-nuts hive mind here..
>>> 
>>> I'm looking for off the shelf connectorized amplifiers with very good 
>>> reverse isolation for doing things like intermod measurements (e.g. 2 
>>> signal generators followed by amps/pads into a combiner) and phase noise 
>>> measurements for a digital receiver.
>>> 
>>> 1-100 MHz kind of frequency range..
>>> 
>>> I've used ZFL-500LN (30dB gain, 27 dB directivity in the data sheet, which 
>>> I interpret as 57dB reverse) , ZX60-4016 (really more of a microwave amp, 
>>> and not so hot reverse wise.. 25 dB)
>>> 
>>> I'm not particularly cost constrained, so a higher power amp (which also 
>>> reduces distortion products from the amp) followed by pads is always an 
>>> alternative.
>>> ___
>>> time-nuts mailing list -- time-nuts@febo.com
>>> To unsubscribe, go to 
>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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>>> 
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>>> 
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Re: [time-nuts] high rev isolation amps

[Rob Sherwood .]

I forgot to add, after the step attenuators at the output of the combiner, 
there is a 10 dB pad right at the back of the radio to provide a better return 
loss to the combiner. 

Rob, NC0B

Sent from my iPad

> On Mar 26, 2016, at 6:34 PM, "Rob Sherwood."  wrote:
> 
> I use two ZHL-32A buffer amps, the appropriate Mini-Circuits LPFs, and 20 dB 
> pads into a 4-way Mini-Circuits combiner. I believe it is ports 2&3 that have 
> even better isolation than a 2-way combiner.  These buffer amps run on 24 
> volts, where the ZFL-500LN doesn't have the output capability to test 100+ dB 
> radios.  Some tests need a third signal source and complimentary buffer amp 
> and associated items. 
> 
> To test a K3S or an IC-7851, it also requires HP 8642A generators that have 
> lower phase noise than these top of the line rigs.  Even my 8662A generators 
> are not good enough, though they were 5 years ago.  Now add the Flex 6700 and 
> the ANAN-200D, the RMDR performance of a hand full of rigs is amazing. 
> 
> Unfortunately transmitter performance has not kept pace with receiver 
> improvement. 
> 
> It will be interesting to test the new IC-7300 DSR with knobs (and lots of 
> menus). 
> 
> Rob
> NC0B
> 
> Sent from my iPad
> 
>> On Mar 26, 2016, at 6:00 PM, "jimlux"  wrote:
>> 
>> 
>> 
>>> On 3/26/16 2:30 PM, Rob Sherwood. wrote:
>>> You cannot add the directivity and gain.  Doesn't work that way.  Rob, NC0B.
>> 
>> Yeah, I kind of figured that after getting the S parameters from 
>> minicircuits.
>> 
>>> Sent from my iPad
>>> 
 On Mar 26, 2016, at 2:00 PM, "jimlux"  wrote:
 
 
 
 Consulting the time-nuts hive mind here..
 
 I'm looking for off the shelf connectorized amplifiers with very good 
 reverse isolation for doing things like intermod measurements (e.g. 2 
 signal generators followed by amps/pads into a combiner) and phase noise 
 measurements for a digital receiver.
 
 1-100 MHz kind of frequency range..
 
 I've used ZFL-500LN (30dB gain, 27 dB directivity in the data sheet, which 
 I interpret as 57dB reverse) , ZX60-4016 (really more of a microwave amp, 
 and not so hot reverse wise.. 25 dB)
 
 I'm not particularly cost constrained, so a higher power amp (which also 
 reduces distortion products from the amp) followed by pads is always an 
 alternative.
 ___
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 https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
 and follow the instructions there.
 
 
 
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 https://support.onlymyemail.com/view/report_spam/ODExMjI6MTg2NjQ0MTI4Mjpyb2JAbmMwYi5jb206ZGVsaXZlcmVk
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>> 
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Re: [time-nuts] high rev isolation amps

[jimlux]

On 3/26/16 3:25 PM, Bruce Griffiths wrote:

On Saturday, March 26, 2016 09:30:30 PM Rob Sherwood. wrote:

You cannot add the directivity and gain.  Doesn't work that way.  Rob, NC0B.

Sent from my iPad

Minicircuits would disagree with that and its their amplifier.

Bruce




Well, it's a bit inconsistent between gain, directivity and S parameters.

at 5.4 MHz the ZFL-500LN has the following S parameters @ 15 V in the 
.s2p file (there's two units' measurements in the files)


S11 -35.5, -32.1
S21  29.7,  29.5
S12 -47.5,- 47.2
S22 -39.5, -28.3

On the other hand, the data sheet "typical data" says: at 5.4MHz 27.9 dB 
gain, 26.5 dB directivity, which Minicircuits defines as isolation-gain 
 (implying isolation is 54.4)

http://www.minicircuits.com/pdfs/ZFL-500LN.pdf

Maybe there's some sort of assumption about source/load impedance (e.g. 
not necessarily perfect 50 ohms)






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Re: [time-nuts] high rev isolation amps

[John Miles]

> I'm looking for off the shelf connectorized amplifiers with very good
> reverse isolation for doing things like intermod measurements (e.g. 2
> signal generators followed by amps/pads into a combiner) and phase noise
> measurements for a digital receiver.
> 
> 1-100 MHz kind of frequency range..
> 
> I've used ZFL-500LN (30dB gain, 27 dB directivity in the data sheet,
> which I interpret as 57dB reverse) , ZX60-4016 (really more of a
> microwave amp, and not so hot reverse wise.. 25 dB)
> 
> I'm not particularly cost constrained, so a higher power amp (which also
> reduces distortion products from the amp) followed by pads is always an
> alternative.

Lots of options at http://www.spectradynamics.com, also see the LNDA series at 
http://www.wenzel.com.  

-- john, KE5FX
Miles Design LLC

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Re: [time-nuts] high rev isolation amps

[jimlux]

On 3/26/16 4:14 PM, Richard (Rick) Karlquist wrote:

Nothing has come to my attention in the last
35 years that is superior for buffer amplifiers
to the simple cascade of grounded base transistors
as described by numerous NBS/NIST papers.
The chain usually starts with a common emitter
(with emitter degeneration resistor), which
is an even older NBS classic.

I realize you asked for an OTS connectorized
version.  Unfortunately, I have never seen
one of these offered in said 35 years.


Yeah, i've spent a while looking through various catalogs..

Odd that nobody sells one: sure, it's probably a limited market, but 
there's plenty of companies that sell limited market widgets (e.g. I'm 
surprised Wenzel doesn't sell one.. in the online catalog info, they 
don't even give S12 data of any kind)





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Re: [time-nuts] high rev isolation amps

[Bruce Griffiths]

On Saturday, March 26, 2016 10:57:01 AM jimlux wrote:
> Consulting the time-nuts hive mind here..
> 
> I'm looking for off the shelf connectorized amplifiers with very good
> reverse isolation for doing things like intermod measurements (e.g. 2
> signal generators followed by amps/pads into a combiner) and phase noise
> measurements for a digital receiver.
> 
> 1-100 MHz kind of frequency range..
> 
> I've used ZFL-500LN (30dB gain, 27 dB directivity in the data sheet,
> which I interpret as 57dB reverse) , ZX60-4016 (really more of a
> microwave amp, and not so hot reverse wise.. 25 dB)
> 
> I'm not particularly cost constrained, so a higher power amp (which also
> reduces distortion products from the amp) followed by pads is always an
> alternative.
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> instructions there.
These seem to be somewhat scarce.
One option is to add a unity gain high reverse isolation amplifier after your 
favourite low noise RF amp.
Even these are scarce so constructing one may be your only option.improve 
distortion.
A direct coupled series chain of CB stages should suffice.
Either a push-pull setup or applying feedback around the first stage emitter 
will input  
Packaging and cable leakage may limit the achievable reverse isolation to a 
bit below 120dB.

Bruce
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Re: [time-nuts] high rev isolation amps

[Richard (Rick) Karlquist]

Nothing has come to my attention in the last
35 years that is superior for buffer amplifiers
to the simple cascade of grounded base transistors
as described by numerous NBS/NIST papers.
The chain usually starts with a common emitter
(with emitter degeneration resistor), which
is an even older NBS classic.

I realize you asked for an OTS connectorized
version.  Unfortunately, I have never seen
one of these offered in said 35 years.
When I worked for Agilent, there was an IC
version made by a captive fab.  It was
never spun off as a commericial part via
the semiconductor division (which is now
Avago).

In the early 1980's, I designed a crystal
oscillator and buffer amplifier for the
HP 10816 rudibium standard.  The crystal
was a 10811 crystal and used the Colpitts
oscillator from the 10811.  The Colpitts
in the 10811 fed a grounded base amplifier
via the crystal.  In the 10816, I used a
cascade of 3 GB amplifiers.  This worked
better than the original 10811 buffer amplifier.

Rick

On 3/26/2016 10:57 AM, jimlux wrote:

Consulting the time-nuts hive mind here..

I'm looking for off the shelf connectorized amplifiers with very good
reverse isolation for doing things like intermod measurements (e.g. 2
signal generators followed by amps/pads into a combiner) and phase noise
measurements for a digital receiver.

1-100 MHz kind of frequency range..

I've used ZFL-500LN (30dB gain, 27 dB directivity in the data sheet,
which I interpret as 57dB reverse) , ZX60-4016 (really more of a
microwave amp, and not so hot reverse wise.. 25 dB)

I'm not particularly cost constrained, so a higher power amp (which also
reduces distortion products from the amp) followed by pads is always an
alternative.
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Re: [time-nuts] high rev isolation amps

[Bruce Griffiths]

On Saturday, March 26, 2016 09:30:30 PM Rob Sherwood. wrote:
> You cannot add the directivity and gain.  Doesn't work that way.  Rob, NC0B.
> 
> Sent from my iPad
Minicircuits would disagree with that and its their amplifier.

Bruce
> 
> > On Mar 26, 2016, at 2:00 PM, "jimlux"  wrote:
> > 
> > 
> > 
> > Consulting the time-nuts hive mind here..
> > 
> > I'm looking for off the shelf connectorized amplifiers with very good
> > reverse isolation for doing things like intermod measurements (e.g. 2
> > signal generators followed by amps/pads into a combiner) and phase noise
> > measurements for a digital receiver.
> > 
> > 1-100 MHz kind of frequency range..
> > 
> > I've used ZFL-500LN (30dB gain, 27 dB directivity in the data sheet, which
> > I interpret as 57dB reverse) , ZX60-4016 (really more of a microwave amp,
> > and not so hot reverse wise.. 25 dB)
> > 
> > I'm not particularly cost constrained, so a higher power amp (which also
> > reduces distortion products from the amp) followed by pads is always an
> > alternative. ___
> > time-nuts mailing list -- time-nuts@febo.com
> > To unsubscribe, go to
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> > 
> > 
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Re: [time-nuts] high rev isolation amps

[jimlux]

On 3/26/16 2:30 PM, Rob Sherwood. wrote:

You cannot add the directivity and gain.  Doesn't work that way.  Rob, NC0B.



Yeah, I kind of figured that after getting the S parameters from 
minicircuits.



Sent from my iPad


On Mar 26, 2016, at 2:00 PM, "jimlux"  wrote:



Consulting the time-nuts hive mind here..

I'm looking for off the shelf connectorized amplifiers with very good reverse 
isolation for doing things like intermod measurements (e.g. 2 signal generators 
followed by amps/pads into a combiner) and phase noise measurements for a 
digital receiver.

1-100 MHz kind of frequency range..

I've used ZFL-500LN (30dB gain, 27 dB directivity in the data sheet, which I 
interpret as 57dB reverse) , ZX60-4016 (really more of a microwave amp, and not 
so hot reverse wise.. 25 dB)

I'm not particularly cost constrained, so a higher power amp (which also 
reduces distortion products from the amp) followed by pads is always an 
alternative.
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Re: [time-nuts] high rev isolation amps

[Rob Sherwood .]

You cannot add the directivity and gain.  Doesn't work that way.  Rob, NC0B. 

Sent from my iPad

> On Mar 26, 2016, at 2:00 PM, "jimlux"  wrote:
> 
> 
> 
> Consulting the time-nuts hive mind here..
> 
> I'm looking for off the shelf connectorized amplifiers with very good reverse 
> isolation for doing things like intermod measurements (e.g. 2 signal 
> generators followed by amps/pads into a combiner) and phase noise 
> measurements for a digital receiver.
> 
> 1-100 MHz kind of frequency range..
> 
> I've used ZFL-500LN (30dB gain, 27 dB directivity in the data sheet, which I 
> interpret as 57dB reverse) , ZX60-4016 (really more of a microwave amp, and 
> not so hot reverse wise.. 25 dB)
> 
> I'm not particularly cost constrained, so a higher power amp (which also 
> reduces distortion products from the amp) followed by pads is always an 
> alternative.
> ___
> time-nuts mailing list -- time-nuts@febo.com
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Re: [time-nuts] high rev isolation amps

[Alex Pummer]

you may need to touch the solder iron, but it is worth it >60dB 
isolation MAXIM, MAX2470, made for VCO buffer ...

73
KJ6UHN
Alex

On 3/26/2016 10:57 AM, jimlux wrote:

Consulting the time-nuts hive mind here..

I'm looking for off the shelf connectorized amplifiers with very good 
reverse isolation for doing things like intermod measurements (e.g. 2 
signal generators followed by amps/pads into a combiner) and phase 
noise measurements for a digital receiver.


1-100 MHz kind of frequency range..

I've used ZFL-500LN (30dB gain, 27 dB directivity in the data sheet, 
which I interpret as 57dB reverse) , ZX60-4016 (really more of a 
microwave amp, and not so hot reverse wise.. 25 dB)


I'm not particularly cost constrained, so a higher power amp (which 
also reduces distortion products from the amp) followed by pads is 
always an alternative.

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[time-nuts] high rev isolation amps

[jimlux]

Consulting the time-nuts hive mind here..

I'm looking for off the shelf connectorized amplifiers with very good 
reverse isolation for doing things like intermod measurements (e.g. 2 
signal generators followed by amps/pads into a combiner) and phase noise 
measurements for a digital receiver.


1-100 MHz kind of frequency range..

I've used ZFL-500LN (30dB gain, 27 dB directivity in the data sheet, 
which I interpret as 57dB reverse) , ZX60-4016 (really more of a 
microwave amp, and not so hot reverse wise.. 25 dB)


I'm not particularly cost constrained, so a higher power amp (which also 
reduces distortion products from the amp) followed by pads is always an 
alternative.

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