[time-nuts] HP5370B & HP5345B Front-End IC Redesign Effort

Mon Jan 25 15:32:10 UTC 2016

Getting back to the original question, years ago I was told but could not  
confirm that HP was buying up 5345's because of a Government commitment to  
replace front ends. If they had to go to such matters I doubt we will be 
able to  find a solution. 
In my home counter work I tried but ended up using boards out of  5345's
Bert Kehren

In a message dated 1/25/2016 10:01:18 A.M. Eastern Standard Time,  
bruce.griffiths at xtra.co.nz writes:

I've  been considering this for some time.The key is the replacement for 
the  triggered phase locked oscillator based interpolators.
FPGA based TDCs  aren't yet quite good enough.
Off the shelf TDC chips are a little better  but still fall a little short 
in performance.

Whilst a TAC approach can  achieve around 4ps or so (eg various Wavecrest 
instruments) a lot of discrete  parts are  likely to be required.

My crude testing of a triggered  damped sinewave generator sampled by an RF 
ADC indicates that an event time  stamp noise of 5ps or better appears 
feasible. 

The technique of  exciting a high Q saw bandpass filter with an impulse and 
digitising  the  output is probably more expensive and complex than  
desirable.

Bruce

On Monday, 25 January 2016  6:04 PM, Bob Camp <kb8tq at n1k.org> wrote:

Hi

Since the  front end chips are mixed signal ASIC’s, it will take more than 
a bit of time  to 
replace them directly. Re-doing the entire front panel board is the  most 
likely way to “fix”
the problem. The question is - why do that at all?  Just do a PC instrument 
that does the same
thing as the counter with way  less effort…..

Bob

> On Jan 24, 2016, at 6:02 PM,  Dimitri.p <dimitri at dotp.com> wrote:
> 
> Someday , someone  will get bored with everything else and give it a try, 
you know, in their  spare time.
> The time when these counter were new was a long while  ago.
> Back then an amplifier chip with 500MHZ BW was a much bigger deal  than 
it is in 2016.
> ...but spare time is permanently on backorder ....  :)
> 
> Dimitri
> 
> At 06:15 AM 1/24/2016, Bob Camp  wrote:
>> Hi
>> 
>> Back when these counters (5345,  5370, 5335) all were new, the inputs 
were
>> the weak link on all of  them. There were known âdonât do thatâ things 
on the line
>> that  would blow out each of them. Regardless of the level of care and 
yelling,  inputs
>> blew on a fairly regular basis. Probably 10% of the  counters went back
>> for repair over a 5 year period. It was always  a âswap out the entire 
boardâ sort
>> of repair and never was under  $1K. We regularly spent the price of a 
new counter
>> each year on  repairs. If there had been an easy way to fix them,  (or 
even to  just
>> pay $500 for the chip) we would have done it.
>>  
>> Bob
>> 
>> > On Jan 24, 2016, at 8:34 AM,  Dale Cannon <dalecan1 at cfl.rr.com> wrote:
>> >
>>  > Funny,
>> >
>> > A friend asked me if I could  replicate the front end for a 5370A, a 
many
>> > years back. I  related to him that replicating the input chip was not a
>> >  trivial task. His 5370A had been used (by someone else) for direct  
testing
>> > of controlled-motion DC motors and the front end had  obviously been
>> > overstressed by voltage spiking. At the time,  I had considered 
replicating
>> > the front-end probe circuit of a  K100D logic analyzer: FET diff. pair
>> > followed by an ECL 10216  line driver. Obviously most daughterboard or 
dead
>> > bug  modification approaches have downsides; in the end I just 
couldn't  cut
>> > up the HP front end and told him to search for a more  qualified repair
>> > facility.
>> >
>> >  BAMA boat anchors has the K100D manual and probe schematic.
>>  >
>> >              Dale  Cannon  KS4FA
>> >
>> >
>> >  -----Original Message-----
>> > From: time-nuts  [mailto:time-nuts-bounces at febo.com] On Behalf Of 
Mathew
>> >  Breton
>> > Sent: Friday, January 22, 2016 5:15 PM
>>  > To: time-nuts at febo.com
>> > Subject: [time-nuts] HP5370B  & HP5345B Front-End IC Redesign Effort
>> >
>> > I  was gifted an HP 5370B with the usual problem: front-end problems,
>>  > probably due to overstress. It is currently up and running again with 
a  set
>> > of 5345A series A3/A4 boards as I wasn't able to get a  cheap pair of
>> > 5088-706x hybrid ICs.
>> > This  sounds like a common problem. As a result, I'm designing an  
open-source
>> > drop-in (hopefully) replacement. My hat is off to  the original IC 
designer,
>> > as it is not a trivial effort due  to the wide input signal common-mode
>> > range, and very tight  trigger timing requirements. Other items (like 
the
>> > E-ECL)  output) are also adding a bit of extra effort.
>> > I'm hoping  that someone(s) might be interested in working with me on 
it. I
>>  > would like to have my assumptions and math checked before I start  the
>> > detailed design phase, and perhaps contribute some better  ideas.
>> > In addition, it would be really helpful if someone  could run a few 
rise-time
>> > dispersion tests on an instrument  with a working "B"-series A3/A4 PCB 
set
>> > (my unit obviously  doesn't qualify).
>> > Regards,
>> > Mat  Breton
>> >  _______________________________________________
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