Yes, I'm pretty sure they are different.

Malcolm


On 16 February 2016 10:29:04 p.m. "Barry n4buq@knology.net [TekScopes]"
<TekScopes@yahoogroups.com> wrote:

One has a small broken spot on the housing on one side and a sticker on the
other. The other one has neither. Unless they removed the sticker (the
side that's broken would be face down in the other picture so that's hard
to tell), I think they're different.

Thanks,
Barry - N4BUQ

----- Original Message -----

From: "hewpatek@gmail.com [TekScopes]" <TekScopes@yahoogroups.com>
To: TekScopes@yahoogroups.com
Sent: Tuesday, February 16, 2016 4:15:16 PM
Subject: [TekScopes] Re: Probes for 2445A

I found these two P6131s in the States: #361487515390 and #121890749622

AFAI can see, this is the same item twice. Same photograph even or am I
wrong? I share your views on the way the cable is tied. One of the worst
things one can do to probe cables is cause damage by torsion.

David H is right where he states that all the accessories would be there with
the (new) Texas probes.
Disadvantages of these Texas probes: More expensive than our most recently
addressed items, less flexible cable, slightly bigger probe body.
The P6131 (and other probes in this family) allows HF adjustment as well,
after removing the plastic cover of the attenuator block. This is how you
"modify"the probes for better behaviour with non-24XX 'scopes.

Raymond

Hi Dwayne,
The "ideal" filter in high ambient light conditions is a circularly
polarized filter. The ambient light passing through it is circularly
polarized in one direction (CW or CCW, I don't remember which), but when it
reflects (off the glass CRT in this case) the direction of circular
polarization is reversed. So none of it is able to get back through the
filter. The light from the phosphor goes through the filter (and is also
polarized) but since it doesn't reflect before getting to the viewers eye it
is not blocked.
The filter improves the CONTRAST, but any filter (including this one)
reduces the BRIGHTNESS. There are situations where this is an acceptable
compromise. The viewing hood is another good compromise. For analog scopes
the best solution by far was the Micro Channel Plate. But then with the
advent of digital scopes CRTs were quickly replaced with LCDs which had the
additional advantage of color.
Dennis Tillman W7PF

The reason I think it is secondary emission and not an optical effect
is that it cuts off abruptly at the edge of the halo and the diameter
of the halo does not change with intensity. The elections always hit
the phosphor with the same energy from the total acceleration creating
the same secondary emission; intensity just varies how many of them
there are.

After lots of data collection, historical weather checking, and polling, Saturday, APRIL 9th
is the date for the next Sphere Stuff Day and Okanagan Valley-wide Radio Amateur swap meet. This gives those in Washington & Oregon time to recover from Puyallup, and should be good weather for both travel and display for everybody. This will be at Sphere Research, in West Kelowna, BC, about 4 hours from Vancouver. See our website for all the contact details and exact address. Starts 9am, but set up for those to display starts at 7am, and we can accommodate 2 Rvs and some limited overnight guests.

We will have tons of test equipment, (Tek, HP, Boonton, Fluke, PMI/Wavetek and much more) spare parts, plug-in modules, manuals and salvage units. Also tons of free electronic goodies of all kinds, as well as dirt cheap items, PLUS a wide range of ham gear and related items from ICOM to Collins for selling, swapping and testing. There is a lot of very cool stuff we are clearing out to make space, so whether you want RF parts, transmitting tubes, test gear, CRTs, nicads, scopes, meters, parts or what-have-you, you WILL find it here. There will also be solar panels, tons of high quality panel meters, Tek 11K items, time code systems (for that home launch pad you've been working on), and a huge assortment of crystals, filters and precision oscillator modules. Susan will also provide Visa/MC and Paypal services for payments if needed.



Want space to show and sell your gear, just CONTACT WALTER to reserve a spot, strictly first come, first served. Trunk/truck sales are fine, or you can set up a table, as you wish. We can provide power for some locations, and we will have some interesting test gear to allow you to demo and verify your stuff. YES, we take requests for specific items you may be interested in, and YES we will post a list in advance of some key items and prices for those that just can't get up here, but shipping costs can be annoying for big items, which is exactly why we suggest showing up in person. Those that have been here in the past have had a great time, so we invite you to drop by and snorkel through the goodies to your heart's content. Plus, who knows what fabulous treasures others will bring to trade?



We may also be able to set up a BBQ spot for snacks, and we will have off-air frequency checks, RF power testing, and a master frequency reference to let you check your counters and other gear. Plus, lots of help and advice from a great cross-section of people you don't get to see so often.


All in all, it should be a great time. RSVP if you need exhibit space, or just to say hi, and remember that we do take requests to set out just the items you need (we have 4 storage buildings, we can't set it ALL out). If you have been missing a good surplus store experience for a while, come by and get that taken care of here!


Remember, Saturday, April 9th. I will post again as we get closer to remind you of the date.



all the best,
walter & susan (walter2 -at- sphere.bc.ca)
sphere research corp.
http://www.sphere.bc.ca/test

One has a small broken spot on the housing on one side and a sticker on the other. The other one has neither. Unless they removed the sticker (the side that's broken would be face down in the other picture so that's hard to tell), I think they're different.

Thanks,
Barry - N4BUQ

I totally agree with you, David re. the bleed not being caused by the mesh. I totally missed the dot-concentric nature of the "halo". and the brightness tapering off nicely instead of the interference-like rings that accompany the mesh' effect. Secondary (electron) emission is a possibility but photon scattering/dispersion and bleed within the phosphor could be part of it. The video was made in relatively low light as well.

Raymond

I found these two P6131s in the States: #361487515390 and #121890749622

AFAI can see, this is the same item twice. Same photograph even or am I wrong? I share your views on the way the cable is tied. One of the worst things one can do to probe cables is cause damage by torsion.

David H is right where he states that all the accessories would be there with the (new) Texas probes.
Disadvantages of these Texas probes: More expensive than our most recently addressed items, less flexible cable, slightly bigger probe body.
The P6131 (and other probes in this family) allows HF adjustment as well, after removing the plastic cover of the attenuator block. This is how you "modify"the probes for better behaviour with non-24XX 'scopes.

Raymond

On 16 Feb 2016 13:45:13 -0800, you wrote:

Does anyone know if the "bleed" on the screen is normal for a CRT screen like the one on the
465M? Here's a video of mine as I turn up the intensity:

Yes, it is perfectly normal. It is partly caused by normal scattering, partly (mostly the halo-like disc) by the scan expansion mesh that these CRT's use to increase the horizontal and vertical deviation sensitivity (and possibly reduce the deviation sensitivity to PDA acceleration voltage).
You'll find that intensity is fully satisfactory in almost all cases long before this effect becomes disturbing. Standard good practice is to not increase intensity beyond a level that permits good visibility, for a number of reasons.

Raymond

It looks normal to me.

I think the ghosting directly surrounding the bright parts of the
trace is secondary emission from the electrons hitting the screen; the
high anode voltage from the PDA (post deflection acceleration) pulls
them back where they strike the phosphor surrounding the current beam
position. All oscilloscopes with PDA display this behavior.

The scan expansion mesh creates a ghost which is *not* aligned with
the beam (except in the very center) and is not normally visible. If
you want to see it, remove the input signal and use a slow sweep so
that you can watch the beam progress across the screen. The ghost
from the scan expansion mesh will follow the beam position catching up
at the center of the screen and then precede the beam to the right.

That is about the same price as a new Chinese made Texas probe which
would also work. Texas is either the OEM for the current crop of
Keysight oscilloscope probes (and Rigol and probably others) or they
are both made by the same company.

<http://www.ebay.com/itm/Two-new-250MHZ-Oscilloscope-clip-probes-w-readout-pin-/220306079644>;

If you buy those, then you get all the little probe tip accessories as
well. They have two high frequency adjustments on the compensation
box so they can be adapted to different oscilloscopes although I did
not have to adjust mine for use below 200 MHz.

Thanks to David DiGiacomo for correcting me on this. I did not even
notice that the DC restorers are on a separate board from the z-axis
amplifier. I have not had my 7904 apart that far.

The z-axis board includes the amplifiers and adjustments including the
grid bias control. I think you could get by with just making
measurements to verify proper operation but changing it should do no
harm and looks to be the easiest thing to do.

On 16 Feb 2016 06:39:38 -0800, you wrote:

Right. So far, I've not torn into the HV sections of the power supply. Replacing/Fixing the Z-axis board is on the path of least resistance...

On Mon, 15 Feb 2016 22:56:40 -0700, you wrote:

On Mon, Feb 15, 2016 at 10:31 PM, David <davidwhess@gmail.com> wrote:

agree that your proposed steps are the way to go. The z-axis DC
restorer is the most likely suspect so replace or rebuild the z-axis
board

Except the DC restorer is in the high voltage module, not on the Z-axis board...

Does anyone know if the "bleed" on the screen is normal for a CRT screen like the one on the
465M? Here's a video of mine as I turn up the intensity:

Yes, it is perfectly normal. It is partly caused by normal scattering, partly (mostly the halo-like disc) by the scan expansion mesh that these CRT's use to increase the horizontal and vertical deviation sensitivity (and possibly reduce the deviation sensitivity to PDA acceleration voltage).
You'll find that intensity is fully satisfactory in almost all cases long before this effect becomes disturbing. Standard good practice is to not increase intensity beyond a level that permits good visibility, for a number of reasons.

Raymond

Does anyone know if the "bleed" on the screen is normal for a CRT screen like the one on the 465M? Here's a video of mine as I turn up the intensity:

https://youtu.be/0qielKd25RE https://youtu.be/0qielKd25RE

it's a 2 metre.

>
Yeah, I had seen that and I'm not sure if it could be accomodated in a 1.3m without component change. These probes have several adjustments "under the hood", for those with the right equipment.

Re Probe suitability:

Googling "Tektronix P6131" shows a link to a useful pdf at Tek.com. In my Google results, it's at #2.

Raymond

On 16 February 2016 at 20:23, hewpatek@gmail.com [TekScopes] <
TekScopes@yahoogroups.com> wrote:

I confirmed to the seller that I would like to buy them if they are good
(cable etc.)
The seller is on this Marktplaats for 6.5 years, which usually means that
they are ok. He's got some other "serious/professional" stuff for sale ATM
as well.
I'll let you know as soon as I get a response.

​Thanks Raymond​

You know there are several versions of these probes? Firstly, there are
different cable lengths: These are all "nice and short" 1.3m length, i.e.
highest BW. Also, there's an Option 25 (I think), which has the larger,
more traditional (6 mm) tip. AFAI could see, these are not Option 25.

​I thought that was the P6133 with the Option 25?

​

Should you want to (start with) a spare cable: There's one for sale "brand
new" from Israel on Ebay # 231844909513.

​Tempting. I might get that if I have a P6131 complete - it's a 2 metre.

Malcolm​


[Non-text portions of this message have been removed]

On 16 February 2016 at 20:12, John Clark johnclark05@outlook.com
[TekScopes] <TekScopes@yahoogroups.com> wrote:

I found the old Tek catalogs very helpful for this. The latest catalog
available on the TekWiki site is from 2000 but on page 500 it lists the
suggested replacement probes for the discontinued instruments, including
the 2445A.

<http://w140.com/tekwiki/wiki/Tek_Catalogs>;

​Thanks. These seem to be quite specific and don't mention that you can use
a P6131 on a 2445A (for example).

Malcolm​

Malcolm,
I confirmed to the seller that I would like to buy them if they are good (cable etc.)
The seller is on this Marktplaats for 6.5 years, which usually means that they are ok. He's got some other "serious/professional" stuff for sale ATM as well.
I'll let you know as soon as I get a response.

You know there are several versions of these probes? Firstly, there are different cable lengths: These are all "nice and short" 1.3m length, i.e. highest BW. Also, there's an Option 25 (I think), which has the larger, more traditional (6 mm) tip. AFAI could see, these are not Option 25.

Should you want to (start with) a spare cable: There's one for sale "brand new" from Israel on Ebay # 231844909513.

Raymond

Malcom,
I found the old Tek catalogs very helpful for this. The latest catalog available on the TekWiki site is from 2000 but on page 500 it lists the suggested replacement probes for the discontinued instruments, including the 2445A.

<http://w140.com/tekwiki/wiki/Tek_Catalogs>;

John

To: TekScopes@yahoogroups.com
From: TekScopes@yahoogroups.com
Date: Tue, 16 Feb 2016 18:56:17 +0000
Subject: [TekScopes] Probes for 2445A


























Hi,



Before I spend $200 on 4 P6133 probes (ebay #351442258034) shipped to the

UK, am I getting the correct ones for my Tek 2445A? Is that a good price?



Thanks,

Malcolm



[Non-text portions of this message have been removed]

On 16 February 2016 at 19:16, 'Colin Herbert' colingherbert@blueyonder.co.uk
[TekScopes] <TekScopes@yahoogroups.com> wrote:

Yes, I think so. In future, you could always take a peek here:

http://www.barrytech.com/tektronix/probes/tekprobes.html

You'll find a wealth of info on Tek probes, including compatibility,
original prices, eBay prices, etc..

​Thanks Colin. Yes, I knew about that list but​ didn't want to risk $200 on
my interpretation.

Malcolm


[Non-text portions of this message have been removed]

Made a mistake in my recent msg.Here is a link (in Dutch . Please Yahoo, don't let me down on this:

<http://www.marktplaats.nl/a/doe-het-zelf-en-verbouw/meetapparatuur/m1020754709-tektronix-p6131-probes.html?c=8c285449651fa109c354bbabe740c1b&;previousPage=lr>

Raymond

Hi Malcolm,
I don't think that's a very good price at all.
P6133's are regularly available in (continental) Europe at lower prices. The other day, four P6131's (300 MHz, well suited for anything from 2445(X) to 2465/67(X)) € 25 each, which is typical. Two are left at the moment.
P6138/39's etc. are more expensive - and not as easily adapted to a 24XX.
Like the probes in your link, the low-inductance accessory "pins" don't seem to be part of the deal though.
I'll buy them for you if you want. I would try and get confirmation that cables are in perfect condition.
P6106(A)'s (as an example) are well suited for your 2445(X) as well and not expensive.

Raymond