开云体育

On May 5, 2024, at 18:51, jspencerg via groups.io <jspencerg@...> wrote:

?Yes, I'm surprised about the lack of traffic on forums and YT about the old keithleys. I have working 2000 dmm, 236, and 610C units. I am getting into the fix with a 619. I was lucky to get a printed manual for the 619. I intend to have another go with my 228 after further honing of my chops.

Thank you, Dave. I’m wondering whether that 6C10 was used in a production instrument or an in-house fixture. I just checked the web and it commands crazy prices on eBay. Audiophiles have clearly fallen in love with its triple-triode sonic magic.

Tom


Sent from an iThing; please forgive the typos and brevity

On May 4, 2024, at 12:58, Dave Wise <d44617665@...> wrote:

?I don't know which scope used compactrons. I do know a cal fixture sort of did.
From my notes:

Tektronix 067-0502-01 Amplitude Calibrator.

The voltage regulator originally used the 6GE8/7734
signal pentode/power triode, but later switched to the 6G11
signal pentode/beam power tube, triode-connected in a purpose-built adaptor.

Besides the 12BU pinout (6AL11 and 6G11) the adaptor is made for,
the 12EZ tubes (6AD10 6BF11 6BY11 6T10) can probably work,
with a new adaptor.

Dave Wise
________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Tom Lee <tomlee@...>
Sent: Saturday, May 4, 2024 12:24 PM
To: TekScopes@groups.io <TekScopes@groups.io>
Subject: Re: [TekScopes] 6C10 Tube

I’m curious: which Tek scope used compactrons?

Cheers
Tom
Sent from an iThing; please forgive the typos and brevity

On May 4, 2024, at 11:23, Bill Riches via groups.io <bill.riches@...> wrote:

?Help! I am looking for a 6C10 tube.
73,
Bill, WA2DVUCape May, NJ

On May 5, 2024, at 08:34, Joel Setton via groups.io <setton@...> wrote:

?Hi,

I also have a few Keithley instruments :
- one 480 Picoammeter, works great
- One 616 digital electrometer which was "flaky" when I got it. I have since replaced the dual FET (Q301 A/B) in the Autoranging Amplifier. I also installed a standard BNC with an isolated mount to replace the input Triax connector, which was missing when I bought the unit.
I replaced the op-amp on the input board with an LM308. The original chip was the source of low-level AC oscillations, which resulted in unstable readings.
I also designed a small board with a 68HC11 which plugs into the QA408 socket, which normally carries the LSI-2 chip on the logic board. This was done as a protection against a potential failure of the original SL35155 chip, which is pure unobtainum.
Now the 616 is future-proof and it works great !
I even sold a few of these replacements boards for the SL35155 on a popular auction site. If anyone is interested, just drop me a PM.
- I also have a 261 Picoampere source, which was the cause of countless headaches because of erratic drift. At first I thought it just needed to be calibrated, but weekly recalibration is not what you expect to do ! Finally, I found that the 200-ohm calibration potentiometers were prone to random changes in cursor resistance, and since cursor current is several milliamps, this resulted in degraded accuracy. I couldn't find any replacements for the pots, and concluded that the design of the power regulator with these potentiometers was inherently flawed. One day I decided to bite the bullet and I designed a new regulator board, using good cermet trimpots in a scheme where the cursor current is close to zero. This performed exactly as expected, and I have not seen any significant drift in output current ever since.
If anyone is interested in the new regulator design, I have schematics and a few blank PCBs available.

That's all !
Cheers,
Joel

Same here, at the close by Walmart. If I hold the handle so I touch
the metal I do not get the shocks. But let a gap form and Whammo! But
not always, so cart differences, humidity differences?

Frank DuVal

On 5/4/2024 9:49 PM, Dave Casey wrote:

I too have dealt with shocks from the cart at my grocery store. I
attributed it to the cart building up charge by rolling. A good test
might
be to hang a dragging chain from the cart, but I've never bothered.

Dave Casey

Same here, at the close by Walmart. If I hold the handle so I touch the metal I do not get the shocks. But let a gap form and Whammo! But not always, so cart differences, humidity differences?

Frank DuVal

On 5/4/2024 9:49 PM, Dave Casey wrote:

I too have dealt with shocks from the cart at my grocery store. I
attributed it to the cart building up charge by rolling. A good test might
be to hang a dragging chain from the cart, but I've never bothered.

Dave Casey

I too have dealt with shocks from the cart at my grocery store. I
attributed it to the cart building up charge by rolling. A good test might
be to hang a dragging chain from the cart, but I've never bothered.

Dave Casey

I too have dealt with shocks from the cart at my grocery store. I
attributed it to the cart building up charge by rolling. A good test might
be to hang a dragging chain from the cart, but I've never bothered.

Dave Casey

On Sat, May 4, 2024, 7:09 PM Dave Seiter via groups.io <d.seiter=
att.net@groups.io> wrote:

Interesting; last week I was at one of the Costcos I visit frequently,
and I had the same experience (which has NEVER happened before, and I've
been shopping there since the mid 80's). The charge would build up very
quickly (maybe 6-8 steps), then discharge between my hands/fingers and the
plastic grip of the cart. Most of the time it discharged while I was
gripping it, not when I let go and re-grasped it. It seemed like it was
building up a charge until it could overcome cracks in the plastic or ???.
No discharges onto other metal surfaces. Same old shoes/jeans etc.
Outside the store in the parking lot everything was normal.
-Dave
On Saturday, May 4, 2024 at 09:31:40 AM PDT, cheater cheater <
cheater00social@...> wrote:

Hi all,
I frequent a large grocery market nearby and inevitably every time I
go there I get electrical shocks. I walk around with a cart and often
if I touch a metal fixture (fridge, mesh rack) I get a painful shock.
Sometimes I get a shock if I leave the cart for a few seconds and then
touch its metal mesh.

I was wondering what everyone thought. At first I thought it would be
ESD, but why would it be so extreme? It happens every time. I live in
a place that's pretty dry - RH goes under 20% regularly - and being on
a plain it has a lot of wind, which could create triboelectric
charging. But I'm not really sure about this.

I don't know which way the ESD happens. Is my body discharging into
the cart? Is the cart discharging into my body? Is my body discharging
into the racks or vice versa? How can one check the directionality of
ESD?

One theory about ESD I have is that the fixtures get charged and my
body gets the charge applied to it. This however isn't necessarily
true to me because eg today I got a painful shock from touching the
inside metal surface of a fridge, and that's supposed to be earthed.

Another theory is that as I walk around in the store, as I move around
with the cart, that charges my body. I wear rubber sandals and the
cart has rubber wheels. That would mean I'm a conductor, attached to a
large antenna (the cart's mesh frame), moving through dry air,
insulated from the ground. The ground is made out of some sort of high
impact ceramic-ish tile. But then why would my own cart shock me just
mere seconds after letting go of it? I was unloading my groceries for
the cashier.

My third theory is that this whole facility has a lifted earth
potential. There's an industrial area nearby and they may be dumping a
lot of current into earth which would create a situation where walking
on the ground charges you, and then touching something that's low-Z to
neutral discharges your body (in this case this would be the earthed
fridges etc).

I was wondering how people would approach diagnosing this problem, and
how you would fix it if you had the ability to change anything about
the facility at hand - more as a thought exercise, but if I figure out
what's going on I'm going to write to the company.

Thanks