[time-nuts] More Z3801/Tbolt comparisons

GandalfG8 at aol.com GandalfG8 at aol.com
Fri Sep 4 16:48:45 UTC 2009

In a message dated 04/09/2009 16:32:09 GMT Daylight Time,  
phill.r1 at btinternet.com writes:

I must  say that much of what you have stated is right, I have a 53131A 
counter  and the basic time-base is a joke, but agreed, we mostly use a 
common  external reference with our instruments.
There are some exceptions, as I am  finding with a very recently purchased 
HP 8657A Sig. Gen. that has the  option 001 oven oscillator. This is a 1998 
production (made in the US),  the TCXO would seem to be a very stable 
with coarse and fine  adjustment - after running for 48 hours its holding 
Mhz to ^10. In fact  it would seem to be somewhat better than the TCXO in 
Marconi 2024 Sig.  Gen. - - hence my singing the praises of HP.
Hi Roy
I suspect the 8657A option 001 is likely to be a 10811B, which also  
appears in quite a lot of other HP kit and is also the better of the options for  
the 53131A and 53132A.
They are certainly very nice oscillators.

The  large number of Racal 199# on the UK market in recent times are I 
suggest, ex UK military issue and as portable instruments have probably  
a rough life, and have frequently been stored for ten years in  somewhat 
environments. I would suggest that buying equipment that has  come from a 
commercial origin, and has been part of a rack test set-up,  have been 
cared for and sometimes have had very little use. What do  you others think 
about this theory ?
You're quite right that the majority of 199x counters available in  recent 
times are ex-mil but that doesn't always mean a hard life, although  I agree 
there can be an element of risk involved when buying  them.
My first 1991, bought a few years ago, was ex-mil but had never been issued 
 and was still new in its original box, having been taken out just once 
since  original calibration to check it was still "serviceable".
The one just bought is also ex-mil, this one has been used  but looks to 
have been very well treated.
It carries a label indicating the warranty ran out in 2001, so I assume it  
was manufactured in 2000, with last calibration expiring in April  2009.
Although it's fitted with the manual pouch for portable use it doesn't show 
 any signs that it's actually been used portable, the case and front and  
rear panels are unmarked, so I suspect it may have just seen bench use.
There's no obvious problems with the front panel switches either, which is  
another good sign, although, of course, that could change tomorrow:-)
It's very likely that there's a lot more of all sorts of test  gear, on 
Ebay at least, that's ex-mil rather than ex-commercial so it's  really quite 
difficult to avoid unless prepared to always buy from dealers who  are able to 
guarantee previous ownership, and also prepared to pay their  much higher 

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