Brad Thompson via Groups.Io wrote on 12/6/2019 10:29 A

Hello--

I'm offering FS sets of NOS concentric control knobs. These have longitudinally-grooved
surfaces and black cursor markings which contrast nicely with the aluminum knob material.

The top knob has a black insert.? Each knob gets secured to its control shaft by two
.050-inch hex setscrews. A .jpg-format photo is available on request.

Bottom knob: 0.625 inches in diameter, 0.56 inches high, 0.25 inch through hole
Top knob: 0.425 inches in diameter, 0.56 inches high, 0.125 inch blind hole.

(Please note that the knobs are made from aluminum, a conductive metal,
and hence will pose a shock hazard if you're accustomed to the bad practice
of floating the ungrounded chassis of an instrument.)

Each set comprises FOUR top/bottom pairs and as a bonus while
the supply lasts, four skirted plastic knobs with 0.125-inch
brass-insert blind hole and one 0.050-inch setscrew.

I'm asking $10.00 per package? (four two-piece knobsets plus bonus knobs), which includes
USPS first-class mail to U.S. locations.

Questions welcomed, PayPal honored.
Thanks, and 73--

Brad? AA1IP

-----Message d'origine-----
De?: [email protected]
<[email protected]> De la part de Alex
贰苍惫辞测é?: 20 décembre 2019 10:31
??: [email protected]
Objet?: [HP-Agilent-Keysight-equipment] HP Agilent 34330a current shunt

I wanted to ask what is the opinion on the 34330A current shunt.
Occasionally one needs to measure current somewhat above the 10Amps which is
the maximum that my 973A/974A handheld DMMs allow. So I was wondering if
this 30A external plugin shunt adapter would be a cost effective addition to
keep on hand, of course considering that this would also require beefier
connecting test leads that are current rated accordingly. But given the ebay
price range for a 34330A being at $130-$300, I wonder if these numbers
realistically make sense, not that I would even consider buying one just for
occasional use at those prices anyhow. Since all of them have been listed
for months now, and perhaps they are just the leftover overpriced bunch
waiting for a desperate buyer, what would be a realistic lower price
expectation for a working one in decent shape?

Or perhaps would other alternatives like a current probe adapter
(34134A/34135A) be a better alternative? On the other hand I already have a
FW-Bell GC-100D 200Amp AC/DC stand alone clamp-on "current gun" but it has a
single range 3.5 digit readout up to 199.9, so measurements towards the
lower end of that scale are not ideal, although still workable if need be.
The gun also has two separate output jacks which I tried to use a couple of
times but the output voltage never did make much sense in comparison to the
actual measured current indicated on the display, which was correct. Maybe I
was doing something wrong there, but the clamp by itself works fine when it
gets used once in a while.

Of course yet another alternative that comes to mind would be to just buy a
sturdy precision 0.01 or 0.001 ohm resistor at Mouser/Digikey and mount it
inside a small metal enclosure with in/out jacks to use as a stand alone
shunt, so it does not even need to stay attached directly or even near to
the DMM.

I really don't have any very high precision needs, which are usually
satisfied with either one of the multiple 4.5-digit 974A's on the bench, and
certainly nothing beyond the capability of my "higher end" 3468A/3478A pair
of not-calibrated for a long time DMMs. But still the idea of having a
plug-n-play 30Amp quick expansion for the handheld DMM like the 34330A shunt
when occasional needs arise still sounds interesting, specially when it is
an HP product.

I am open to comments and suggestions. Thanks.

On Dec 19, 2019, at 8:06 PM, "ghnatiuk@..." <ghnatiuk@...> wrote:

Dennis,
At the time the 3468A was being developed, the LCD technology at Hp was in codevelopment with cooperation between the Loveland Instrument group and the Corvalis Calculator group.? There were no backlit LCDs at the time to be designed into the instrument.? This was a new technology.? We actually started with the LCD display from the 41C calculator in the engineering prototypes of the 3468A until the larger LDC eventually used in the 3468/78/57/88 was developed and prepared for manufacturing.? The 3468/78 and the LCDs were in development from 1978 -1981.? The project "KEY" for the 3468A was the first electronic calibration DMM for Hp.? ?The project began and started to ramp up after July 1978 and I joined as chief analog designer (5) for the front end signal conditioning in October 1978.? By February 1979 we had our full design team in place:
(1)? Project manager
(2)? Firmware/digital?
(3)? A/D and digital interface?
(4)? Hybrid switches and? DC? front end and attenuator
(5)? Ohms / AC / DC interface / Motherboard PCB and Input hybrid layout with fineline resistor networks
(6)? Power supply / battery backup / LCD? display
(7)? Mechanical and industrial design

Most of us were new engineers fresh out of university except for 3 members of the team (1),(2),(7)

The mission was to design a 5-1/2 digit DMM with full electronic CAL using less than 100 parts and for a parts cost of $100 or less.? We got close to the goal but had to increase the parts count because to meet safety requirements and that required for the necessary protection circuits for ESD and potential customer abuse.? That took more parts than first anticipated.

George Hnatiuk? ? Dec 19, 2019
Have a happy holiday

On 2019. 12. 19. 0:27, Dave McGuire wrote:

On 12/18/19 6:18 PM, ian.p.brown@... wrote:

I am considering purchasing a used HP 4195A network spectrum analyzer
that has both the display and measurement units but is missing the
cables to connect them. How difficult is it to source or find cables to
connect them? Is there anything unique about the cables? Any idea how
much replacement cables would cost?

It's not tough at all. You'll need one cable with 50-pin AMP Champ
series connectors (what people who don't bother to learn call
"centronics" or "SCSI" connectors), and if memory serves a DE9 cable, I
don't recall the gender but that should be easy to figure out.

50-pin AMP Champ cables have been commonly used in telephony for
decades, and are known there as "25-pair" cables. They are easy to find
and not terribly expensive; I think I paid about $15 for a two-foot one,
new, on eBay.

The DE9 cables are commonly available via eBay or Amazon, cheap.

If you end up pulling the trigger on it, I can help you with the
specifics when the time comes. I can tell you that I very much love the
4195A, it's a fine and very capable instrument.

-Dave