Anyone know what Circut Bob Pease was going on about?

[John Larkin]

Has it got an external input? I've got an ancient (or is that well-aged
and "even more stable"?) GenRad OXCO which I can plug into any generator
or counter that will take an external reference to make it more accurate.

With your rather more serious (than mine) operations, I'd think you
could put in one rubidium or cesium reference (and or some new-ish
method tied to GPS I'm not overly familiar with) and distribute it
throughout your labs/plant/wherever, so long as your counters and/or
generators will take an external reference frequency. Assuming decent
cable termination and appropriate drivers, I don't see that you'd need
more than one "really good" reference.

We have an SRS SC-cut ovenized oscillator, that we mounted in a rack
box with a power supply. Ditto an ebay rubidium. We even have an old
HP cesium standard, which is a big deal to fire up, so we seldom use
it. All three typically agree to something like 30 ppb.

Cool: trigger a scope from the cesium and look at the rising edge of
the rubidium, at 10 ns/cm. Ten minutes later, it's barely moved.

But still, a grand for a TCXO is insane. It probably costs them 20
bucks or so. So, no Agilent counter.

John

 

[Winfield]

I need a new universal frequency counter. The low-end Agilent looks
nice, but it has a crappy XO, and they want another THOUSAND DOLLARS
for a mere TCXO.

Spend you money on a GPS-based super-accurate
10MHz reference to use all around your lab.

 

[John Larkin]

Spend you money on a GPS-based super-accurate
10MHz reference to use all around your lab.

We already have some good 10 MHz sources. But it's a nuisance to have
to connect a small, portable counter to a big reference source.

Why a grand for a TCXO?

John

 

[Ecnerwal]

We already have some good 10 MHz sources. But it's a nuisance to have
to connect a small, portable counter to a big reference source.

It should not be. Run some dedicated cables, put on a particular color
of heat shrink, leave them there like air hoses or electrical outlets.

 

[John Larkin]

It should not be. Run some dedicated cables, put on a particular color
of heat shrink, leave them there like air hoses or electrical outlets.

Distributing 10 MHz all over two floors of a building would be a major
project... just for the benefit of one Agilent counter. Ethernet was
bad enough.

John

 

[Jamie]

Distributing 10 MHz all over two floors of a building would be a major
project... just for the benefit of one Agilent counter. Ethernet was
bad enough.

John

we did that at the capacitor company I consulted at on the side.

GPS time base receiver (10 mhz output), into a distribution amplifier
with isolated outputs (20 count). each rung went to a work station to
be used as the reference for capacitor testers.

 

[Ecnerwal]

Distributing 10 MHz all over two floors of a building would be a major
project... just for the benefit of one Agilent counter. Ethernet was
bad enough.

I'm sort of surprised that you only have one thing (which you don't even
have, if I understand correctly, since you don't want to buy it without
the OXCO, and the OXCO is overpriced) that would benefit from easy
access to a reference frequency, especially since you have already
bothered to get in several reference frequency sources.

 

[Spehro Pefhany]

We already have some good 10 MHz sources. But it's a nuisance to have
to connect a small, portable counter to a big reference source.

Why a grand for a TCXO?

John

So they can sell the 'stripped' version for a grand cheaper to the
penny pinchers? Maybe something like that.

 

[Rich Grise]

I'm sort of surprised that you only have one thing (which you don't even
have, if I understand correctly, since you don't want to buy it without
the OXCO, and the OXCO is overpriced) that would benefit from easy access
to a reference frequency, especially since you have already bothered to
get in several reference frequency sources.

The way I read it, I assumed John was talking about pulling all that
cable.

Thanks,
Rich

 

[Ecnerwal]

The way I read it, I assumed John was talking about pulling all that
cable.

Yes, I got that. I just find it hard to justify not doing so as "it's
only for this one meter I haven't bought, so why bother."

Obviously there _are_ other things which he does have that benefit from
good references, or he would not have any of those, much less several.

Thus, a one-time painful cable-pull-fest would make all those
applications, and any future ones (even if he never buys the particular
counter in question) easy, rather than a hassle. It's sort of like "Why
go to the bother of running all that pipe, when I can get water in a
bucket?" Or "Why go to the bother of running all that pipe, when I can
drag out a portable air compressor and a hose if I need compressed air?"

The way you use things, be they water, compressed air, or 10MHz
reference frequencies, changes depending on how much of a pain it is to
access them. I suspect that the price of one new counter without OXCO
might cover a fleet of older ones from *B*y that will be just fine if
they are fed a known-good reference. Some signal generators can also
take an external reference for greater precision, if there's one coming
to the bench anyway.

Enough, I'll stop here.

 

[John Larkin]

Yes, I got that. I just find it hard to justify not doing so as "it's
only for this one meter I haven't bought, so why bother."

Obviously there _are_ other things which he does have that benefit from
good references, or he would not have any of those, much less several.

Thus, a one-time painful cable-pull-fest would make all those
applications, and any future ones (even if he never buys the particular
counter in question) easy, rather than a hassle. It's sort of like "Why
go to the bother of running all that pipe, when I can get water in a
bucket?" Or "Why go to the bother of running all that pipe, when I can
drag out a portable air compressor and a hose if I need compressed air?"

The way you use things, be they water, compressed air, or 10MHz
reference frequencies, changes depending on how much of a pain it is to
access them. I suspect that the price of one new counter without OXCO
might cover a fleet of older ones from *B*y that will be just fine if
they are fed a known-good reference. Some signal generators can also
take an external reference for greater precision, if there's one coming
to the bench anyway.

Enough, I'll stop here.

We have a bunch of HP5370B's, which are 20 ps single-shot time
interval counters, that also do frequency to 100 MHz. They all seem to
stay within 30-50 ppb of the rubidium, so they don't really benefit
from an external reference. But they're 4U rackmount beasts, not
something I want in my office mini-lab. I'm in the market for a nice
little "universal" counter, preferably new, and haven't found anything
really suitable.

My Keithley 2100 DVM is a pretty good frequency counter, too, so maybe
I'll just wheel over a 5370 when I need something serious.

Heck, my TDS2012 is a pretty good counter, too.

John