Date   

O.T. question on MoVs

 

Hi all,
Somewhat off topic power supply related.
I got some MoVs from aliexpress which I ordered to use in series to protect a 277VAC, 90mA mains supply from high transients.

They ought to be a pair of 270VAC units in series, shorted across the 2 wire AC supply from high transients.
07D271 type part. They capacitive coupled design (2.2uf, 450VAC polypropylene Caps on both lines) allow for 900VAC transient operation without issue.
But ..they shipped unmarked and the supplier is not responding. So it seems I need to do a test bed to validate their function.
Any advice on the approach?


Re: General Radio 874 Connector, inner conductor "bendies"

Richard Knoppow
 

I looked at a couple of 874 s just now. The tips of the small center contacts are pointed and slightly tapered toward the center. The larger of the center contacts are tapered toward the inside and slightly bent outward so that the opposing contacts slide over each other and form a continuous tube. Its somewhat the same as the outside contacts.
While the photo may be an optical illusion it does not look right. I don't think the connector was twisted but someone may have put a 274 banana plug into it and bent it. The 274 _can_ be used on an 874 but one must be careful not to stress it. The design is such that the outer shell makes contact first and pretty much prevents the mating plugs from being twisted.
The 874 is a pretty good connector but has the disadvantage of not having a precise reference plane. They can act as a short sliding line. Even when locked the reference plane is uncertain.

On 8/6/2019 2:44 PM, Roy Thistle wrote:
Hi All:
Apologies, if this has been covered (there are a lot of posts on 874!).. but the picture on Tekwiki of the GR-874 (the one with the plug facing the viewer... so you can see into it)… well that picture shows two of the leaves of the center conductor, bent in at the corners, and so having little "bendies" barbs, or tangs. (You have to see the picture!).
http://w140.com/tekwiki/wiki/GR-874_connector.
My initial question is… Is that normal, or is the center conductor of the connector damaged? (You can see a bit of those "bendies" on the leaves of the outer conductor, in the picture, too.) My initial guess is the matching, inserter GR-874, after being rotated, and mated, has damaged the insertee? If so, how does the mated pair maintain 50 ohms?
Best regards and wishes.
Roy
--
Richard Knoppow
dickburk@ix.netcom.com
WB6KBL


Re: General Radio 874 Connector, inner conductor "bendies"

Merchison Burke
 

I don't see any bending. What I see are the sharp edges have been chamfered which makes it easy to mate with another GR874 connector. All my GR874 connectors look the same.

On 2019-Aug-06 5:44 PM, Roy Thistle wrote:
Hi All:
Apologies, if this has been covered (there are a lot of posts on 874!).. but the picture on Tekwiki of the GR-874 (the one with the plug facing the viewer... so you can see into it)??? well that picture shows two of the leaves of the center conductor, bent in at the corners, and so having little "bendies" barbs, or tangs. (You have to see the picture!).
http://w140.com/tekwiki/wiki/GR-874_connector.
My initial question is??? Is that normal, or is the center conductor of the connector damaged? (You can see a bit of those "bendies" on the leaves of the outer conductor, in the picture, too.) My initial guess is the matching, inserter GR-874, after being rotated, and mated, has damaged the insertee? If so, how does the mated pair maintain 50 ohms?
Best regards and wishes.
Roy



---
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Re: General Radio 874 Connector, inner conductor "bendies"

george edmonds
 

Hi Roy

These are hermaphrodite connectors and the picture that you refer to does not appear damaged.

73 George G6HIG On Tuesday, August 6, 2019, 10:44:41 PM GMT+1, Roy Thistle <roy.thistle@mail.utoronto.ca> wrote:

Hi All:
Apologies, if this has been covered (there are a lot of posts on 874!).. but the picture on Tekwiki of the GR-874 (the one with the plug facing the viewer... so you can see into it)… well that picture shows two of the leaves of the center conductor, bent in at the corners, and so having little "bendies" barbs, or tangs. (You have to see the picture!).
http://w140.com/tekwiki/wiki/GR-874_connector.
My initial question is… Is that normal, or is the center conductor of the connector damaged? (You can see a bit of those "bendies" on the leaves of the outer conductor, in the picture, too.) My initial guess is the matching, inserter GR-874, after being rotated, and mated, has damaged the insertee?  If so, how does the mated pair maintain 50 ohms?
Best regards and wishes.
Roy


General Radio 874 Connector, inner conductor "bendies"

Roy Thistle
 

Hi All:
Apologies, if this has been covered (there are a lot of posts on 874!).. but the picture on Tekwiki of the GR-874 (the one with the plug facing the viewer... so you can see into it)… well that picture shows two of the leaves of the center conductor, bent in at the corners, and so having little "bendies" barbs, or tangs. (You have to see the picture!).
http://w140.com/tekwiki/wiki/GR-874_connector.
My initial question is… Is that normal, or is the center conductor of the connector damaged? (You can see a bit of those "bendies" on the leaves of the outer conductor, in the picture, too.) My initial guess is the matching, inserter GR-874, after being rotated, and mated, has damaged the insertee? If so, how does the mated pair maintain 50 ohms?
Best regards and wishes.
Roy


Re: 7000 series empty plugin frame $12 shipped

John
 

I suppose no connectors as they were on the PCB. I am interested but without the male connector it is kind of pointless for what I want.

John
VK2DLP


Re: Tekmate 2402 rebuild and programming

A Rhodes
 

Oops. The search term I mention should be:
"Github Tek-user"

Sorry!


Re: Tekmate 2402 rebuild and programming

A Rhodes
 

I have uploaded to Github a few different repositories under the user name "Tek-User".

You can use google for "github two-user".

There are 4 project repositories. One on writing new software for the 2402.

Another on repairing an old 2402 and getting it working. And then upgrading the 2402 to a 133MHz 586 EBX motherboard and the complexities that are encountered.

Another project ports the new programming from the first project listed here and placing it on an arduino. A tiny arduino can largely replace the entire 2402 as an embedded system with the user interface through the scope.

I have found and placed in these repositories various software packages relating to the 2402.

One software package I have NOT found is the Tektronix "Program Development Software". This apparently has the source code used for the "dso-sh" and "dos-app" software packages provided by Tektronix. I have searched for the development software by thoroughly googling all variations and themes of this topic and found nothing.

Does anyone here have any leads for the Program Development Software?

-Tony


Re: 2440 deal

Kevin Oconnor
 

Yea, get one for me!
Kevin


Re: Simulator

Tony Fleming
 

Can you point me to the place where you talk about it?
Thank you!
Tony

On Mon, Aug 5, 2019 at 11:19 PM Abc Xyz <yawrdanza@gmail.com> wrote:

Harvey,

Did you get s chance to compare my Simulator Voltages with your Simulator
Voltages yet?
JR




Re: 2445 LVPS Issues

Tony Fleming
 

Yes, couple screws makes it easy! That is what I did with my scope.

On Mon, Aug 5, 2019 at 5:16 PM Chuck Harris <cfharris@erols.com> wrote:

Whenever you remove the power supply from a 2465 family
scope, remove all of the screws that hold the right side
of the rear panel, and pull it out 1/2 inch.

-Chuck Harris

n4buq wrote:
Tapped lightly on the shaft, the collet released, and the impeller came
right off. The collet is indeed broken. That's quite fragile (as stated)
as I don't recall putting very much torque on that shaft at all.

Now that I have the impeller off, though, I still cannot lift the LVPS
out because the motor shaft protrudes through the hole in the rear plate.
Does that shaft normally stick out that far? If not, then maybe I
displaced the shaft in this process.

If the shaft does normally stick out that far, then how does one extract
the power supply? The manual states it should just lift out but it's a
pretty tight fit and I can't see where I can tilt it far enough to let the
shaft clear the frame.

Stumped again...

Thanks,
Barry - N4BUQ



Re: letter series plugins

Michael A. Terrell
 

This was 45 years ago, on an Army base where the newer part of the base
had enough steam for all of the buildings. I was in a drafty, WWI building
that had been a Barracks, Mess hall and steam plant for the Lend Lease
program. It was called Delta Field during WWII, and it was a transfer point
where Russian pilots picked up American built planes and weapons to fight
Germany. That building was their barracks. It was only slightly better than
the steel Quonset huts the Infantry used. Those used a layer of heavy snow
to keep them warmer than the outside winds. I realize that this is off
topic, but I'm sure there are a lot of new Tek instruments there, after the
base was reopened as a missile base. I probably had to only Tek scope on
base in the '70s. There mgiht have been one at the Nuclear power plant, but
that had been shut down before I arrived and any equipment that wasn't
bolted down was shipped out before they filled the control room with
concrete to seal it off.

I never saw any electric heaters for sale on base, just heaters for car
batteries, lower heater hoses and dipstick heaters. -79F was recorded
there, at one point, and -40 was common. I wore winter field gear inside on
wind days. At the time I was stationed there, it was the Cold Weather
Training Center. It was 105 miles to Fairbanks, and Ft. Greely was
considered one of the worst duty stations in the US Army. I kept my mind
off of it as much as possible by rebuilding an obsolete TV station with
whatever parts I could get my hands on. That included Tek and HP equipment
that had been used and abused by untrained and under trained staff. It was
either that, or turn into one of the angry drunks, like one I worked with.
BTW, I still have a Weller SP23 soldering Iron I bought in the PX, to
repair Stereos and TVs on the side. It still works, but most of the
internal threads are gone. I couldn't buy tips up there, so I got some
scrap brass welding rods and borrowed a die to thread it. Backwoods
engineering at its finest! :)

On Mon, Aug 5, 2019 at 10:07 AM Chuck Harris <cfharris@erols.com> wrote:

Indeed! They can be friendly in the
winter. But a $19 milk shed heater, and
a 2465 scope is quite a bit more cost effective,
is fast enough to do most work, and heats better
too!

-Chuck Harris

Michael A. Terrell wrote:
A vacuum tube Tektronix scope was no problem in the winter, at a TV
station
in Alaska. It might even get the control room to 40F, if it and both
transmitters were on! I would turn on the studio's Halogen lights to warm
up, when it was below freezing in the control room. There wasn't enough
waste heat left from the return water to the old boilers to keep us warm.
That was 45 years ago, and the scope was sufficient to repair the
electronics in the Analog Monochrome days.I also had four Tektronix RM529
waveform monitors that were Hybrids to help provide heat. :)



Re: 2440 deal

Jeff Woolsey
 

On 8/5/19 9:24 PM, Bob Albert via Groups.Io wrote:
That looks pretty good.  I see there is more than one. 
On Monday, August 5, 2019, 09:20:48 PM PDT, Robert Simpson via Groups.Io <go_boating_fast=yahoo.com@groups.io> wrote:

Is this a valid or good deal? I might try and get one if it is. Currently I do not have any digital scopes and would like to try one out. I don't actually need it so it would be more for the learning experience.

Bob
https://sfbay.craigslist.org/sby/wan/d/cupertino-500-ms-digital-oscilloscope/6948745001.html
There goes my resale value.  I put about $300 into acquiring and fixing
a pair of them a few years ago, and still have them.  One is my daily
driver, the other excess to my needs.  And I'm just as local.

--
Jeff Woolsey {{woolsey,jlw}@jlw,first.last@{gmail,jlw}}.com
Nature abhors straight antennas, clean lenses, and empty storage.
"Delete! Delete! OK!" -Dr. Bronner on disk space management
Card-sorting, Joel. -Crow on solitaire


Re: 2440 deal

Bob Albert
 

That looks pretty good.  I see there is more than one.  Perhaps I can convince you to buy one for me.  I don't know about shipping, although I will be in Santa Barbara on Saturday at a hamfest.
Let me know what you think.  I live in the Los Angeles area.
Bob

On Monday, August 5, 2019, 09:20:48 PM PDT, Robert Simpson via Groups.Io <go_boating_fast=yahoo.com@groups.io> wrote:

Is this a valid or good deal? I might try and get one if it is. Currently I do not have any digital scopes and would like to try one out. I don't actually need it so it would be more for the learning experience.

Bob
https://sfbay.craigslist.org/sby/wan/d/cupertino-500-ms-digital-oscilloscope/6948745001.html


2440 deal

Robert Simpson
 

Is this a valid or good deal? I might try and get one if it is. Currently I do not have any digital scopes and would like to try one out. I don't actually need it so it would be more for the learning experience.

Bob
https://sfbay.craigslist.org/sby/wan/d/cupertino-500-ms-digital-oscilloscope/6948745001.html


Simulator

Abc Xyz
 

Harvey,

Did you get s chance to compare my Simulator Voltages with your Simulator
Voltages yet?
JR


Re: 2445 LVPS Issues

n4buq
 

That worked and I have the LVPS boards out now. Unfortunately, I can't isolate by sight or smell where the burning odor came from. I see where there are a few RIFA caps that might be suspect but, from what I read about those, the smell when those go bad is significantly worse than a mild burning odor. Still, it could have been a precursor to a full-blowout.

I mentioned that I could see some of the smaller caps leaning a bit and thought that could have been bulging; however, as it turns out, that was due to the cable that powers the fan being routed between two of them and they're bent over slightly to accommodate that.

I did remove the fan motor and confirmed that it still works just fine with an outboard power supply. The spindle seems to have a bit more drag than I think it should so I presume a bit of lube is in order.

Odd how that collet broke. The break is nearly perfect and quite neat. It's almost as if the back end of the collet was glued originally but I doubt that was the case. I can, however, press the collet into the tapered impeller enough to hold it nicely on the motor shaft. Sure wish I'd waited on advice before trudging in like the proverbial bull in a china shoppe and turning that screw...

Thanks again,
Barry - N4BUQ

----- Original Message -----
From: "Chuck Harris" <cfharris@erols.com>
To: TekScopes@groups.io
Sent: Monday, August 5, 2019 5:16:14 PM
Subject: Re: [TekScopes] 2445 LVPS Issues

Whenever you remove the power supply from a 2465 family
scope, remove all of the screws that hold the right side
of the rear panel, and pull it out 1/2 inch.

-Chuck Harris

n4buq wrote:
Tapped lightly on the shaft, the collet released, and the impeller came
right off. The collet is indeed broken. That's quite fragile (as stated)
as I don't recall putting very much torque on that shaft at all.

Now that I have the impeller off, though, I still cannot lift the LVPS out
because the motor shaft protrudes through the hole in the rear plate.
Does that shaft normally stick out that far? If not, then maybe I
displaced the shaft in this process.

If the shaft does normally stick out that far, then how does one extract
the power supply? The manual states it should just lift out but it's a
pretty tight fit and I can't see where I can tilt it far enough to let the
shaft clear the frame.

Stumped again...

Thanks,
Barry - N4BUQ



Re: 2445 LVPS Issues

Renée
 

yes and I have a copy, see attached.
I do not have a need for it on a scope but it looked like it might work for a pin vise too!
nor do I recall who supplied the info....however it is appreciated.
Renée

On 2019-08-05 2:33 p.m., teamlarryohio wrote:
Didn't someone post a drawing from which one could machine one of these
collets a year or three ago?



Re: 2445 LVPS Issues

 

Chuck I have created an update to my 2465 project with your quotes, ...thanks for all the useful info.
https://cdn.hackaday.io/files/1638907011869760/2445-2465%20Fan%20Collet.jpg


Re: letter series plugins

snapdiode
 

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