[time-nuts] Any thoughts on best rubidium?
Peter Gottlieb
nerd at verizon.net
Mon Sep 26 14:55:41 UTC 2011
The kit costs more than the analyzer.
If someone finds a good LCD panel and does the mechanical design for
mounting I can begin work on an "open source" design for the
electronics part.
That would expand the market to far more of us.
On 09/26/11, shalimr9 at gmail.com wrote:
There are aftermarket color LCD replacement available for the HP 8566
and HP 8568 analyzers, either as a do-it-yourself kit, or as a turn-key
service.
Didier KO4BB
Sent from my BlackBerry Wireless thingy while I do other things...
-----Original Message-----
From: [1]EWKehren at aol.com
Sender: [2]time-nuts-bounces at febo.com
Date: Mon, 26 Sep 2011 07:01:36
To: <[3]time-nuts at febo.com>
Reply-To: Discussion of precise time and frequency measurement
<[4]time-nuts at febo.com>
Subject: Re: [time-nuts] Any thoughts on best rubidium?
Roy,
for its time it was the best because of the spectral purity of its Osc.
The
big problem with the unit today is its CRT. Limited life and no
replacements. As rare as Cs tubes. If you can live with 1.3 GHz an
excellent choice,
the 22 GHz version because of source does not have as good
specifications.Also repairable, many parts are readily available.
Bert Kehren
In a message dated 9/26/2011 6:27:59 A.M. Eastern Daylight Time,
[5]phill.r1 at btinternet.com writes:
Bert
What's your opinion of the "old" HP8568B with its max. frequency range
of
1.3 Ghz and its weight of around 100 lbs. - are the more recent
instruments
that much better ?
Roy
--------------------------------------------------
From: <[6]EWKehren at aol.com>
Sent: Sunday, September 25, 2011 10:47 AM
To: <[7]time-nuts at febo.com>
Subject: Re: [time-nuts] Any thoughts on best rubidium?
> If you want low noise in a spectrum analyzer it all comes down to the
> signal quality into the first mixer. Every thing else with today's
> technology
> is down hill.
> Bert Kehren
>
>
> In a message dated 9/25/2011 5:32:31 A.M. Eastern Daylight Time,
> [8]Robert at delien.nl writes:
>
>> One other thing is that some spectrum analyzers aren't really
designed
>> for low noise performance. Since the noise floor is often pretty
high,
>> the design of the whole RF chain (e.g. spur levels and such) might
have
>> assumed that lots of things would be hidden in the grass.
>
> True, it's one of the many selection criterions for selecting the
> instrument that meets your needs.
> I've been looking a the luggable HP series 859x and 856x, preferring
the
> latter because they have a PLL YIG whereas the fist uses a
free-running
> oscillator. But these machines are old, 80's and 90's, pricey, and
not
> really
> THAT good. Add decent range (up to 9GHz to see recent 5.8GHz devices)
and
> a
> tracking generator and before you know it, you'll be paying $6k or
more
> for
> a 20 year old instrument.
>
>> If the
>> analyzer is of the recent "bring a band of RF down to an IF, sample
and
>> FFT it for fine resolution" architecture, such things as the number
of
>> bits in the ADC and the "cleanliness" of the sampling clock might
have
>> been chosen based upon doing 1024 point transforms being displayed
with
>> 100dB dynamic range (10dB/div and 10 divisions).
>
> Most modern instruments do that, at least to some degree. My R&S goes
> down
> to a RBW of 10Hz by just mixing. Additionally RBWs of 5, 3, 2 and 1Hz
are
> achieve by additional FFT. This instrument dates from 2001, but I
don't
> think more recent instruments can achieve a mixing-only RBW of 5Hz or
> below.
>
>> (not to mention the spectrum analyzer actually generating spurious
>> signals. I ran across that one last year and thought I had an
>> interference source, but, no, went back and checked the spec sheet
and
>> it said spurious are <-80dBc, and sure enough, there it was at -82
dBc.
>> And stories about the first LO coming back out through the input are
>> legion.)
>
> Gee, I wish I had consulted this group BEFORE buying my instrument.
I'm
> happy with it and I don't regret anything, but you could have added a
lot
> more arguments in favor or againstA-c-AEURA|
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