Brian
Thanks for the details.
There are a number of problems with crystal filters. A crystal filter
will have a finite bandwidth, and at offsets less than half the
bandwidth the filter won't have a significant effect on the phase noise.
For example the 40MHz xtal filter used in the 8662A
First, thanks for the replies from all.
More info on the LO chain:
1) 5MHz Wenzel OCXO --Custom Osc for me.
2) MSA-1105 buffer MMIC and lumped LPF
3) 5MHz to 10MHz 1N5711 diode based doubler
4) MSA-1105 buffer and lumped LPF
5) 10MHz to 20MHz 1N5711 diode based doubler
6) 20MHz BPF
7) 20MHz
Grant
The trouble with most MMICs is that they usually have too much gain and
insufficient reverse isolation for use in an isolation amplifier.
However when the available signal level is low using an MMIC to boost
the signal to around +13dBm or more can be useful.
They can have quite low close in
Brian
Could you give some more details? I think alternative solutions to
MMICs at 5 and 10MHz would give much lower phase noise.
Bruce's web pages have a number of designs that will get the 5MHz
reference up to 20MHz in 2 stages :-
http://www.ko4bb.com/~bruce/FrequencyMultipliers.html
More info on the LO chain:
1) 5MHz Wenzel OCXO --Custom Osc for me.
2) MSA-1105 buffer MMIC and lumped LPF
3) 5MHz to 10MHz 1N5711 diode based doubler
4) MSA-1105 buffer and lumped LPF
5) 10MHz to 20MHz 1N5711 diode based doubler
6) 20MHz BPF
What kind of BPF? A really narrow crystal
1) 5MHz Wenzel OCXO --Custom Osc for me.
[snip multiplier chain]
What kind of BPF? A really narrow crystal filter would be nice here.
(You have basically reproduced the 8568A/B's 20 MHz reference
section.)
What happens when I put a crystal in series with a crystal filter?
I'd expect it
Maybe I'm missing the decimal point. What's the bandwidth of a crystal
filter relative to the spectrum out of the same crystal used as an osc?
The oscillator's noise floor itself is superb, near -180 dBc/Hz beyond 1
kHz. That is only true until you do something with it. The idea behind the
Looking for comment here...
The background:
I'm working on a sub mm-wave LO chain for
a ham radio application. While chasing issues
of close-in phase (ie: within 1KHz of RF
carrier) by peeling the layers of the onion,
I'm starting to question the performance of
the MMICs that are used as buffers
Hello Brian,
I hope you and yours have the very best of this Holiday Season.
My considerations would be similar to spurious free dynamic range,
keeping all discrete intermodulation products very low, which
would in turn keep the intermodulation noise very low.
When you drive an amp towards and
the real
bleeding-edge work at sub-mm these days.
-- john, KE5FX
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com]on
Behalf Of wa1...@att.net
Sent: Monday, December 15, 2008 8:54 AM
To: time-nuts@febo.com
Subject: [time-nuts] Close-in phase noise
of precise time and frequency measurement
Subject: Re: [time-nuts] Close-in phase noise question...
The painful part is probably the first few stages, if you are starting at 5
MHz. You probably want to do some HP 8662A-like tricks using crystal
filters to shave off the broadband noise below 1 GHz
: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com]on
Behalf Of wa1...@att.net
Sent: Monday, December 15, 2008 8:54 AM
To: time-nuts@febo.com
Subject: [time-nuts] Close-in phase noise question...
Looking for comment here...
The background:
I'm working on a sub mm-wave
I would assume that the bleeding takes place
just after the first molecule has performed it's
dissecting task.
-- Original message from J. L. Trantham, M. D.
jlt...@worldnet.att.net: --
I really enjoy reading the mail on this group, but I thought it was the
'front
wa1...@att.net wrote:
Looking for comment here...
The background:
I'm working on a sub mm-wave LO chain for
a ham radio application. While chasing issues
of close-in phase (ie: within 1KHz of RF
carrier) by peeling the layers of the onion,
I'm starting to question the performance of
the
Sent: Monday, December 15, 2008 5:00 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Close-in phase noise question...
wa1...@att.net wrote:
Looking for comment here...
The background:
I'm working on a sub mm-wave LO chain for
a ham radio application. While
-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com]on
Behalf Of Bruce Griffiths
Sent: Monday, December 15, 2008 5:00 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Close-in phase noise question...
wa1...@att.net wrote:
Looking for comment here
: Re: [time-nuts] Close-in phase noise question...
wa1...@att.net wrote:
Looking for comment here...
The background:
I'm working on a sub mm-wave LO chain for
a ham radio application. While chasing issues
of close-in phase (ie: within 1KHz of RF
carrier) by peeling the layers
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