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 u
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 work
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
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
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 capacita
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
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:
&
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
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
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 i
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 bu
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.
S
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 w
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
>b
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
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.
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
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 dire
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 te
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
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 inco
> 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..
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 emitte
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 combi
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
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:
> >
> >
> >
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
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
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 isolati
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.
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