[time-nuts] HP 5334B C-channel--was Re: Which HP Frequency Counter?

Didier Juges didier at cox.net
Thu Mar 20 22:23:20 EDT 2008


Rick,

Thanks for the interesting bit of history.

I remember a previous post where you told us about the difficult choices you
had to make for the standard "reference" oscillator, which is certainly not
one of the strong point of the instrument. Mine is hooked up to a
Thunderbolt GPSDO, so the oscillator is not used.

Can you tell us the reasons why the standard (no C channel option) 5334B has
most of the parts needed for the C channel except for the counter and two
Shottky packages?

I understand even at $2 the MB506 may have been considered "expensive", but
there are 3 amplifiers (MMIC or BJT?) and a bunch of parts around for
biasing and coupling, and of the two counters I have without option C, they
have all these parts already installed, except for the MB506 and the two
Shottkys.

It looks as if the 5334B was originally intended to have the C channel as
standard, and then the marketing folks decided to make it an option after
the boards were built, but the (two HP 5334B) counters I have are fairly
recent, in the history of the product, so that scenario does not make much
sense.

I must add that I really like my 5334B, I have about a dozen counters here
and the HP 5334B is the one that gets the job first, which is the reason I
would like to add the C channel. That would eliminate one more reason to use
either one of the EIPs or the Advantest.

Didier KO4BB

> -----Original Message-----
> From: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] On Behalf Of Richard 
> (Rick) Karlquist
> Sent: Thursday, March 20, 2008 9:31 AM
> To: Discussion of precise time and frequency measurement
> Subject: [time-nuts] HP 5334B C-channel--was Re: Which HP 
> Frequency Counter?
> 
> I was the project manager and chief EE on the HP5334B 
> project.  The 5334A had a C channel using an HP made divide 
> by 10 prescaler that had a factory cost of ~$100.
> In the 5334B, I replaced this with the Fujitsu MB506 divide 
> by 8 prescaler, which cost something like $2.
> The firmware was changed slightly to account for the 
> different modulus.  This is the ONLY difference in firmware 
> between the 5334A and 5334B counters.
> I considered using the NEC uPB581/2 prescalers.  This class 
> of prescalers is based on "dynamic" flip flops, as opposed to 
> static ones.  These flip flops are only intended for 
> prescaling a clean signal from a local oscillator in a 
> synthesizer.  In a frequency counter application, they work 
> OK on a new clean signal, but will miscount on noisy signals. 
>  "Noisy" here refers to broadband noise, not close in phase 
> noise.  Prescalers are especially sensitive to low frequency noise.
> 
> Now it can be told that we used to test all C channels in all 
> models with an HP8660 synthesizer.  This was not one of HP's 
> best designs, and it has a lot of broadband noise.  [The 
> designers of this unfortunate product redeemed themselves 
> with the 8662, one of HP's flagship products].  In order to 
> properly count the
> 1.3 GHz signal from the 8660, it was necessary to use a high 
> pass filter to keep the 8660's broadband noise from 
> corrupting the measurement.  This was also the case for the 
> previous HP-made divide by 10 prescaler.
> 
> I put a LOT of effort into evaluating various prescalers and 
> trying to put in mitigation measures such as rolling off the 
> low frequencies before they could get to the prescaler.  I 
> eventually decided that the task was hopeless with off the 
> shelf prescalers.
> 
> At the same time, one of the other designers in the lab was 
> working on the 5386 counter, and naturally we compared notes. 
>  This counter used an HP-made static flip flop.
> The FF used in the 5334A was made at the Santa Clara bipolar 
> silicon fab.  The FF used in the 5386 was made in the Santa 
> Rosa fab.  Whether it was the process or the circuit design, 
> the Santa Rosa FF was absolutely bullet proof.  It made error 
> free measurements of the lousiest signals.  The designer of 
> the 5386 delighted in finding new signals to measure and 
> inviting me to a "bake-off" to see who's counter did better.
> Of course, I always lost these contests miserably!
> 
> I would encourage owners of 5334B's w/o the C channel option 
> to consider trying modern static flip flops from vendors such 
> as Micrel and OnSemi, rather than installing the MB506.  You 
> can easily glue an SMT prescaler to the board upside down in 
> the footprint where the MB506 goes, and then connect the 
> "dead bug" with little wires to the MB506 connections.
> 
> Rick Karlquist N6RK
> 
> 
> Didier Juges wrote:
> > The HP 5334A or B with the C channel option has a 
> sensitivity spec of 
> > -30dBm (from memory) up to 1 GHz or so. The C channel has 15mV rms 
> > sensitivity at 1 GHz.
> > 
> > The C channel option is rare, but it only requires 3 parts 
> (a diviser 
> > and two dual-shottkys) and a connector (and a hole in the 
> front panel) 
> > to add it to a 5334B for instance. I have two 5334Bs (one 
> is broken) 
> > and both have the other parts required for the C channel except for 
> > these three. There is a socket for the diviser, the 
> shottkys have to be soldered in.
> > 
> > The C channel input is activated on pressing the '9' key.
> > 
> > Unfortunately, the MB506 diviser (Fujitsu) seems a little hard to 
> > find. If anyone has a spare, let me know. A surface mount 
> equivalent 
> > should not be too hard to put in.
> > 
> > The HP 5316 has similar characteristics and also has a 1 
> GHz option, 
> > which is also rare.
> > 
> > I also have an Advantest TR5823 counter which has the 1.3 GHz input 
> > with 20mV rms sensitivity at 1.3 GHz.
> > 
> > The HP models have reciprocal counting, so they work MUCH 
> better for 
> > low frequency signals.
> > 
> > Didier KO4BB
> > 
> >> -----Original Message-----
> >> From: time-nuts-bounces at febo.com
> >> [mailto:time-nuts-bounces at febo.com] On Behalf Of Jean-Christophe 
> >> Deschamps
> >> Sent: Saturday, March 08, 2008 10:49 AM
> >> To: time-nuts at febo.com
> >> Subject: [time-nuts] Which HP Frequency Counter?
> >>
> >> Dear group,
> >>
> >> I consider buying a used lab frequency counter / timer --preferably
> >> HP/Agilent-- covering from few mHz to perhaps 400 MHz.  
> I'm worried 
> >> that models handling high frequencies seem to be limited 
> to under 100 
> >> mV input signal max. I don't want to destroy an input channel each 
> >> other day when calibrating/repairing some instrument.  
> Also are there 
> >> instruments with high impedance input? 50 Ohm is not quite 
> right for 
> >> investigation in the guts of most designs.
> >>
> >>
> >> Is it possible to find a not-too-old model under $800?  I 
> would like 
> >> to find something in France or UK or Europe, but it seems 
> hopeless in 
> >> this budget.  I would favor a repairable model (with available 
> >> service docs & schematics).
> >>
> >> Your expert advises are more than welcome!
> >>
> >> --
> >> <mailto:jcd at q-e-d.org>jcd at q-e-d.org
> >>
> >>
> >> _______________________________________________
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> >>
> >> No virus found in this incoming message.
> >> Checked by AVG. 
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> >> Date: 3/8/2008 10:14 AM
> >>  
> >>
> > 
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> > 
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