On Mon, 22 Sep 2008 01:01:31 +0200, you wrote:
after reading A low noise 100 MHz distribution amplifier for precision
metrology
by M. Siccardi, S. Römisch, F. W. Walls, and A. De Marchi (NIST),
I have implemented a homebrew version of their design.
Circuits, simulation measurement data are
Gerhard
One trick that has been used for fixed frequency isolation amplifiers =20
is to use a low Q
series tuned LC circuit to short out the resistor in series with the =20
base at the
frequency of interest.
Using a suitable ferrite bead instead of the resistor may
On Tue, 14 Oct 2008 08:35:55 +1300, you wrote:
One trick that has been used for fixed frequency isolation amplifiers
is to use a low Q series tuned LC circuit to short out the resistor
in series with the base at the frequency of interest.
Yes, but when I burn close to 3 Watts /
I've done a redesign of the distribution amplifier without
transformers or other ferrite (apart of dc filters). This required
2 transistor chains in parallel or 96 mA at 24V / Channel.
It runs quite hot but looks like it could work from KHz to 600 MHz+.
Harmonics are down 40 dB at 250 MHz/13
[EMAIL PROTECTED] wrote on 09/24/2008 08:44:30 PM:
On Mon, 22 Sep 2008 15:52:19 +1200, [Gerhard] wrote:
[snip]
For maximum phase stability the BNC connectors should replaced by
threaded connectors such as TNC, SMA , N etc.
The next iteration will have to live with BNC because RS smpd,
On Fri, 26 Sep 2008 16:21:49 -0400, you wrote:
For maximum phase stability the BNC connectors should replaced by
threaded connectors such as TNC, SMA , N etc.
The next iteration will have to live with BNC because RS smpd, hp8662A,
SNA-33 friends all have BNCs and the holes in the 19 front
On 9/26/08 2:36 PM, Gerhard Hoffmann [EMAIL PROTECTED]
wrote:
On Fri, 26 Sep 2008 16:21:49 -0400, you wrote:
For maximum phase stability the BNC connectors should replaced by
threaded connectors such as TNC, SMA , N etc.
The next iteration will have to live with BNC because RS smpd,
Tom Clark, K3IO wrote:
Gerhard -- the discussion between you and Bruce has been very
interesting. I asked a VLBI colleague to look over your design and he
had this comment.
In VLBI, H-Maser frequency standards used to generate local
oscillators at microwave frequencies. We
On Thu, 25 Sep 2008 14:08:51 +1200, you wrote:
You are likely to find that its only practical to cover the 80-120Mhz
region as the NIST and Spectradynamics distribution amplifiers do.
The purpose of the heavy bypassing of the bases of the BFG31 transistors
is to reduce the low frequency
Gerhard
You are likely to find that its only practical to cover the 80-120Mhz
region as the NIST and Spectradynamics distribution amplifiers do.
The purpose of the heavy bypassing of the bases of the BFG31 transistors
is to reduce the low frequency noise at the BFG31 bases, this
Gerhard
Oops! I meant s12 not s21.
Bruce
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Gerhard -- the discussion between you and Bruce has been very
interesting. I asked a VLBI colleague to look over your design and he
had this comment.
In VLBI, H-Maser frequency standards used to generate local
oscillators at microwave frequencies. We have problems with amplitude
In message [EMAIL PROTECTED], Gerhard Hoffmann write
s:
The question is more if the 100r * 100u do anything to de-noise
the LED voltage. Close to the carrier probably not. The problem is
that you nowhere get exact numbers to base a decision on.
Be aware that LED's work both ways: current-light
In message [EMAIL PROTECTED], Gerhard Hoffmann write
s:
The question is more if the 100r * 100u do anything to de-noise
the LED voltage. Close to the carrier probably not. The problem is
that you nowhere get exact numbers to base a decision on.
Be aware that LED's work both ways: current-light
Poul-Henning Kamp wrote:
In message [EMAIL PROTECTED], Gerhard Hoffmann write
s:
The question is more if the 100r * 100u do anything to de-noise
the LED voltage. Close to the carrier probably not. The problem is
that you nowhere get exact numbers to base a decision on.
Be aware
Tom Clark, K3IO wrote:
Gerhard -- the discussion between you and Bruce has been very
interesting. I asked a VLBI colleague to look over your design and he
had this comment.
In VLBI, H-Maser frequency standards used to generate local
oscillators at microwave frequencies. We
Bruce Griffiths wrote:
Tom Clark, K3IO wrote:
Gerhard -- the discussion between you and Bruce has been very
interesting. I asked a VLBI colleague to look over your design and he
had this comment.
In VLBI, H-Maser frequency standards used to generate local
oscillators at
On Mon, 22 Sep 2008 15:52:19 +1200, you wrote:
RF grounding all three electrodes of the BC860 is not good practice.
The BC860 will tend to oscillate when you do this unless the ESR of the
100uF base bypass cap is large enough.
A standard electrolytic? The ESR is less than stellar, see my
Gerhard Hoffmann wrote:
On Mon, 22 Sep 2008 15:52:19 +1200, you wrote:
RF grounding all three electrodes of the BC860 is not good practice.
The BC860 will tend to oscillate when you do this unless the ESR of the
100uF base bypass cap is large enough.
A standard electrolytic? The
It (LTSpice) has some severe limitations for most of the simulations I
have done.
You might bring those up with Mike Engelhardt (the author). He doesn't miss
many tricks.
These need to be supplemented with on board filtering as they aren't
quite as quiet as you need.
Either the NIST style
Hi all,
after reading A low noise 100 MHz distribution amplifier for precision
metrology
by M. Siccardi, S. Römisch, F. W. Walls, and A. De Marchi (NIST),
I have implemented a homebrew version of their design.
Circuits, simulation measurement data are contained in:
Gerhard Hoffmann wrote:
Hi all,
after reading A low noise 100 MHz distribution amplifier for precision
metrology
by M. Siccardi, S. Römisch, F. W. Walls, and A. De Marchi (NIST),
I have implemented a homebrew version of their design.
Circuits, simulation measurement data are contained
Bruce Griffiths wrote:
Gerhard Hoffmann wrote:
Hi all,
after reading A low noise 100 MHz distribution amplifier for precision
metrology
by M. Siccardi, S. Römisch, F. W. Walls, and A. De Marchi (NIST),
I have implemented a homebrew version of their design.
Circuits, simulation
Gerhard Hoffmann wrote:
Hi all,
after reading A low noise 100 MHz distribution amplifier for precision
metrology
by M. Siccardi, S. Römisch, F. W. Walls, and A. De Marchi (NIST),
I have implemented a homebrew version of their design.
Circuits, simulation measurement data are contained
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