On 09/ 9/12 09:03 PM, Bruce Griffiths wrote:
For this particular application a capacitive termination (NIST used such
a termination in their DMTDs) of the IF port followed by a low pass
filter is advantageous.
For precision work screw connectors (SMA, TNC, N etc) are more stable
than bayonet conn
Jim Lux wrote:
On 9/9/12 9:37 PM, li...@lazygranch.com wrote:
What am I missing here? Vce = Vbe, so the diode connected transistor
isn't saturated.
I think it's where the diode is fully conducting, and into the linear
part of the V/I curve, not in the square law part any more.
In normal
On 9/9/12 9:37 PM, li...@lazygranch.com wrote:
What am I missing here? Vce = Vbe, so the diode connected transistor isn't
saturated.
I think it's where the diode is fully conducting, and into the linear
part of the V/I curve, not in the square law part any more.
In normal use the LO port
bject: Re: [time-nuts] HP10514B Mixer Terminations
Hi
….. and of course, once you go into saturation the mixer doesn't look much like
50 ohms any more. Sort of gets us back to terminations again.
Bob
On Sep 9, 2012, at 6:21 PM, Bruce Griffiths wrote:
NIST have indicated that mixe
e and frequency measurement
Subject: Re: [time-nuts] HP10514B Mixer Terminations
Hi
….. and of course, once you go into saturation the mixer doesn't look much like
50 ohms any more. Sort of gets us back to terminations again.
Bob
On Sep 9, 2012, at 6:21 PM, Bruce Griffiths wrote:
&
Hi
….. and of course, once you go into saturation the mixer doesn't look much like
50 ohms any more. Sort of gets us back to terminations again.
Bob
On Sep 9, 2012, at 6:21 PM, Bruce Griffiths wrote:
> NIST have indicated that mixer PN noise measurements with a non dissipative
> terminations
On 09/10/2012 12:21 AM, Bruce Griffiths wrote:
NIST have indicated that mixer PN noise measurements with a non
dissipative terminations (even RF) are intended to be made.
Using a discrete mixer using diode connected transistors may also be
useful at least for 5MHz and 10MHz input frequencies in
In the late 60s I built a VLF upconverter using a ring mixer.
I tried a few different devices for the diodes.
The base/collector junctions of germanium switching transistors
gave the best results.
On 09/09/2012 03:21 PM, Bruce Griffiths wrote:
NIST have indicated that mixer PN noise measurements
NIST have indicated that mixer PN noise measurements with a non
dissipative terminations (even RF) are intended to be made.
Using a discrete mixer using diode connected transistors may also be
useful at least for 5MHz and 10MHz input frequencies in that their
flicker noise can be significantly
Hi
In general, you terminate the mixer in 50 ohms at the RF frequencies (say 10
and 20 MHz). Termination at the "IF" (in this case audio) frequencies is what
turns out to be tricky. Any time you terminate a source in a high impedance,
you get a higher output voltage. Reactance rarely adds noise
Bruce is correct. For best RF performance in an "rf" environment
the use of 50ohms for all ports is a
good start. However, even in RF designs
you can often optimise a mixer spec
with something other than 50 ohms.
With a VLF IF freq like a DMTD, each
mixer model might have an ideal
termination impe
David Kirkby wrote:
On 9 September 2012 18:28, Pascual Arbona wrote:
Hello Brian,
I am a radio amateur and and also in the Time nuts list, At the
moment I am planning to bild a DMTD for experimentation. and as you have a nice
experience in this field , for me
On 9 September 2012 18:28, Pascual Arbona wrote:
>
>
> Hello Brian,
> I am a radio amateur and and also in the Time nuts list, At the
> moment I am planning to bild a DMTD for experimentation. and as you have a
> nice experience in this field , for me will be very wellc
For this particular application a capacitive termination (NIST used such
a termination in their DMTDs) of the IF port followed by a low pass
filter is advantageous.
For precision work screw connectors (SMA, TNC, N etc) are more stable
than bayonet connectors like the BNC.
Bruce
J. Forster wro
Most all of this kinda stuff is built using 50 Ohm 'building blocks'. You
can almost plug them together like Legos.
The HP 10514A is no different:
http://www.ko4bb.com/Manuals/HP_Agilent/HP_10514_Mixer_Jan_1967.pdf
Mini-Circuits (among others) sells loads of different wsuch components.
Your big
Hello Brian,
I am a radio amateur and and also in the Time nuts list, At the
moment I am planning to bild a DMTD for experimentation. and as you have a nice
experience in this field , for me will be very wellcame your help. My ask is
¿whitch is te best temination for
That post had the drawing of the last system (2nd generation), just to
show the setup I was using for the offset generator. (LT1027 preamp).
The new system, which I was testing the mixer terminations, has the
LT1028. Its terminated in 150 pF, a 1 kilo-ohm series resistor and then
a 0.1 uF ca
Hi
If you are just changing C1 when you go to 150 pf, the mixer is still pretty
heavily loaded by R1 and C2. The mixer is only "close" to open circuit with R1
(or R1 plus a coil) at 500 ohms.
Bob
On Mar 30, 2010, at 7:55 PM, Brian Kirby wrote:
> Here's a block/schematic of the last version I
Wavetek/Rockland 5120A Synthesizer.
ewkeh...@aol.com wrote:
Good morning Brian.
What do you use as an OFF SET oscillator?
Thank you
Bert Kehren Miami
In a message dated 3/29/2010 11:31:15 P.M. Eastern Daylight Time,
kilodelta4foxm...@gmail.com writes:
Your correct
Good morning Brian.
What do you use as an OFF SET oscillator?
Thank you
Bert Kehren Miami
In a message dated 3/29/2010 11:31:15 P.M. Eastern Daylight Time,
kilodelta4foxm...@gmail.com writes:
Your correct - your also keeping me up past my bedtime !- I got to
be 9
Your correct - your also keeping me up past my bedtime !- I got to be 90
miles from home tomorrow morning by 7:30 AM
It looks like I got the squarest wave at 150 pF. Lesser capacitance,
give a peaked sinewave, like maybe a second harmonic. Past 200 pF, it
starts rounding. 150pf= XC of
Your poor results at 1kHz have more to do with the 1K +0.1uF low pass
filter which has a cutoff frequency of about 1.6KHz.
This will attenuate the beat frequency harmonics required for high slew
rate at the beat frequency zero crossings.
A filter cutoff of 16kHz (1K + 10nF) should improve the sl
Brian
You should get even better results if you replace the 330pF cap with a
1/4 wave (at the 20MHz sum frequency) coax cable open circuited stub.
Thats around 2.5m of RG 58 coax for example.
Connecting a series tuned circuit (at the sum frequency) across the
mixer IF output should also work
Hi
You can get a *much* more squared output from the mixer than the photos you
show on the scope. The waveform looks a lit like a triangle wave with the tips
chopped off. Normally the fastest edge happens into a capacitive load at RF
that's below about 0.5 J ohms for a "50 ohm" mixer.
Bob
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