[time-nuts] Any thoughts on best rubidium?

Roy Phillips phill.r1 at btinternet.com
Mon Oct 3 09:29:41 EDT 2011

Many thanks to you all for information and opinions. My 8568B is in very 
good condition, and I trust with reasonable usage will last me some time 
yet. I have a couple of 1340A displays to hand - do they share the same CRT 

-----Original Message----- 
From: Orin Eman
Sent: Tuesday, September 27, 2011 4:06 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Any thoughts on best rubidium?


The 8568A/B is spec'd to 1.5 GHz, but will actually scan to 1.7 GHz.  To
demonstrate this, I hooked up a Wavetek 2500 signal generator set to 840
MHz, 0 dBm and put the output into my 8568A.  The second harmonic is clearly
visible and the 8568A can count it - the count display flashes between
1679.99 MHz and 1680.00 MHz.  It shows -39.7 dBm for the second harmonic,
but I haven't checked how far off it is.  Here is a plot captured by John
Miles' HP7470A program:


(You can also see a subharmonic at 420 MHz - the 2500 uses a frequency
doubler to produce frequencies over 550 MHz.)

It's a great SA when it's working, but expect to spend some time spent
fixing it when it's not and if you want to keep it calibrated, well, if you
have to ask...  I was going to fix my 8568A up, sell it and get a
SignalHound.  Somehow, the 8568 is still here!


On Mon, Sep 26, 2011 at 3:27 AM, Roy Phillips 
<phill.r1 at btinternet.com>wrote:

> 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
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