Date   

Re: should you lubricate 10 turn dials

Dale H. Cook
 

On 7/3/2019 11:16 PM, Rolynn K7DFW wrote:

Unknown. Mine are from the boxes that contain the Duodials.
I have never bought one new and have never seen disassembly or maintenance instructions (installation instructions are easy to find online). For about forty years I have worked with turns counters that were already in service. I have scrounged several Duodials from decommissioned equipment and have used some of those for projects that I have built.
--
Dale H. Cook, GR/HP/Tek Collector, Roanoke/Lynchburg, VA
https://plymouthcolony.net/starcity/radios/


Re: should you lubricate 10 turn dials

ROLYNN PRECHTL K7DFW
 

I have the instruction and installation sheets on the Duodial and there is no mention of maintenance lubrication.
Are those available online?

====================================================================================


Unknown. Mine are from the boxes that contain the Duodials.


Rolynn


Re: should you lubricate 10 turn dials

Dale H. Cook
 

On 7/3/2019 4:52 PM, Rolynn K7DFW wrote:

I have the instruction and installation sheets on the Duodial and there is no mention of maintenance lubrication.
Are those available online?
--
Dale H. Cook, GR/HP/Tek Collector, Roanoke/Lynchburg, VA
https://plymouthcolony.net/starcity/radios/


Re: Part needed for Type 576 Curve Tracer

Michael W. Lynch
 

Kurt,
Would you mind looking at my submission in the "Repairs" section of the Type 576 Curve Tracer and see if this is anywhere close to what you are looking for?  I tried to keep it short and to the point.

Sincerely,

Michael Lynch 479-226-0126 Home Phone479-477-1115 Cell Phonemlynch001@excite.commlynch002@gmail.commlynch003@yahoo.com

On Monday, June 24, 2019, 12:58:29 PM CDT, Kurt Rosenfeld <kurt.harlem@gmail.com> wrote:

Michael (and anyone else who wants to improve Tekwiki),

Email me and I will make an account for you. The email address is at the bottom of the top-level main page:

http://w140.com/tekwiki/#/media/File:Kurt_email.gif

When you're logged into the wiki, you can edit pages. Otherwise it's read-only.

-Kurt


Re: should you lubricate 10 turn dials

Greg Muir
 


Re: 7904 excessive shadow/flare

Albert Otten
 

On Wed, Jul 3, 2019 at 10:24 PM, Chuck Harris wrote:


Most telling would be to use a stationary spot, and a
straight edge to see if the radial construction line I
imagined truly predicts the ghost image's spot location.
Chuck,

How to explain that the ghost image of a stationary spot is not a spot but a (fuzzy) full ring of almost 1 div diameter? That's the situation in my 7704A and also more or less visible in the video by Max:
https://www.dropbox.com/s/tfy91d8tq1b6ql9/7904_shadow_flare%20003.AVI?dl=0

Could this be related to the cristal structure of the aluminium layer?
[Apart from that ghost image, in my 7704A there is a disk-like lighted area around the spot with gradually decreasing brightness at larger radii.]

Albert


Re: 7904 excessive shadow/flare

 

On Mon, Jul 1, 2019 at 03:32 PM, Chuck Harris wrote:


The 465, and 475, are known to me to have dome mesh lenses,
...I have seen them broken... but neither exhibit the
phenomenon observed on the 7904. The dome mesh lens shows
itself, in these scopes, by a fuzzy, less sharp beam when
compared to a conventional CRT, that has no lens.
I guess I misunderstood the above and placed a few images showing (a.o.) that precise "7904 -behaviour" on a 465, wondering what phenomenon was meant if not that.

I assumed that since you replied to this thread with
a picture of the same phenomenon we were discussing, only
this time on a 465 CRT, that you knew what we were
talking about.
I thought and think I was and am but when you wrote

neither exhibit the phenomenon observed on the 7904
I got confused since I remembered that exact same behaviour from the 465, albeit only at very high intensity. I guess I should forget about that phrase then.

I agree with you that it's hard to gauge intent over this medium, so we have to be careful. Apology accepted, of course.

Raymond


Re: should you lubricate 10 turn dials

ROLYNN PRECHTL K7DFW
 

Its possible Caig Deoxit fader lube. This has enough solvent action to loosen up old lubricant and leaves a lubricating residue. Very light lubricant and I don't think it can hurt anything. Seems safe around plastics. Works great for pots, I think it might work for the dial.

==============================================================================================

The Beckman Duodial disassembles and is easily cleaned. Nothing more than a rag and a swab is needed.

I have the instruction and installation sheets on the Duodial and there is no mention of maintenance lubrication.

When they are working properly they are very loose and it is evident whey there is no need for 'lubrication' that will gum it up and slow it down.

Rolynn
Tek Bvtn and Sunset 1966-1971


Re: 7904 excessive shadow/flare

Chuck Harris <cfharris@...>
 

The 7904 phenomenon is what we have been discussing.

When a slow, but bright trace sweeps across the screen,
you see both the dot of the normal bright trace, and a
dimmer, fuzzy, ghost spot. The ghost spot appears to be
located on a radial line beginning at the center of the
screen, and passing through the centers of the bright
beam, and the fuzzy "ghost" spot.

It appears to the operator as a fuzzy trace that is
magnified version of the original trace.

For simplicity, I called this the 7904 phenomenon.

I have observed it to exist on many high performance
CRTs, but it is particularly evident (some say annoyingly so)
on the 7904 CRT.

I posit that the effect is caused by the electron beam
striking the CRT screen, and being reflected back into
the CRT at the angle of incidence.

The PDA anode voltage attracts the bounced electrons back
to the screen, where they once again strike, lighting up
the phosphor, and appear in the form of a fuzzy ghost image

The ghost image is always there, but it is most evident
at higher intensities, and at slower than 5ms/div sweeps.

I apologize for taking a "tone" with you.

I assumed that since you replied to this thread with
a picture of the same phenomenon we were discussing, only
this time on a 465 CRT, that you knew what we were
talking about.

I never presumed you weren't knowledgeable, only that you
were intentionally being difficult. It is hard to gauge
intent over this medium.

If the ghost images are indeed caused by electrons bouncing
off of the CRT screen, and the bounced electrons are indeed
brought back to the screen by the PDA's attraction, the
distance the ghost images are from the trace should be
greater with a higher energy electron beam.

This appears to be so, based on your 465 pictures.

Most telling would be to use a stationary spot, and a
straight edge to see if the radial construction line I
imagined truly predicts the ghost image's spot location.

If you try this, be very careful, stationary beams burn
CRTs... even well protected ones, like in the 7904..

-Chuck Harris

Raymond Domp Frank wrote:
...

As said, I'd appreciate you tell me what that specific "phenomenon observed on the 7904" is. I guess you already told us and I missed it but maybe I'll learn from it and please leave out the implied "I'm knowledgeable, you aren't".

Raymond


Re: should you lubricate 10 turn dials

Richard Knoppow
 

Its possible Caig Deoxit fader lube. This has enough solvent action to loosen up old lubricant and leaves a lubricating residue. Very light lubricant and I don't think it can hurt anything. Seems safe around plastics. Works great for pots, I think it might work for the dial.

On 7/3/2019 1:10 PM, Bob Albert via Groups.Io wrote:
I wouldn't lube it.  Just a cleaning.  The dial is pretty standard so finding a replacement shouldn't be hard.
First try squirting solvent into it.
Bob
--
Richard Knoppow
dickburk@ix.netcom.com
WB6KBL


Re: should you lubricate 10 turn dials

ROLYNN PRECHTL K7DFW
 

I wouldn't lube it.  Just a cleaning.  The dial is pretty standard so finding a replacement shouldn't be hard.
First try squirting solvent into it.


=======================================================================================

There is a plastic part inside so I'd stay away from 'solvents'.

It disassembles easily so a good cleaning will work wonders.


Rolynn
Tek Bvtn and Sunset 1966-1971


Re: should you lubricate 10 turn dials

Bob Albert
 

I have two or three dials.  They are interchangeable in general except for the size of the unit.

On Wednesday, July 3, 2019, 01:14:35 PM PDT, wendell19430 <wendellgreene@comcast.net> wrote:

            so far  i have been unable to find a replacement


Re: should you lubricate 10 turn dials

wendell19430
 

so far i have been unable to find a replacement


Re: should you lubricate 10 turn dials

Bob Albert
 

I wouldn't lube it.  Just a cleaning.  The dial is pretty standard so finding a replacement shouldn't be hard.
First try squirting solvent into it.
Bob

On Wednesday, July 3, 2019, 12:39:42 PM PDT, wendell19430 <wendellgreene@comcast.net> wrote:

the ten turn dial for my 1L20 IF center frequency has stopped rotating the pot moves ok when I remove the dial. any help or thoughts will be much appreciated?


should you lubricate 10 turn dials

wendell19430
 

the ten turn dial for my 1L20 IF center frequency has stopped rotating the pot moves ok when I remove the dial. any help or thoughts will be much appreciated?


Re: 7904 excessive shadow/flare

 

On Mon, Jul 1, 2019 at 03:32 PM, Chuck Harris wrote:


The 465, and 475, are known to me to have dome mesh lenses,
...I have seen them broken... but neither exhibit the
phenomenon observed on the 7904. The dome mesh lens shows
itself, in these scopes, by a fuzzy, less sharp beam when
compared to a conventional CRT, that has no lens.
What "phenomenon observed on the 7904" were you referring to?

Indeed, now show that it doesn't happen with an overly bright
non mesh lens system. I have seen the same stuff on my very old,
and probably now no longer working 513D, which has neither a lens,
nor an aluminized CRT phosphor. It did have a very high anode
voltage...12KV.

I have also seen it happen on a 545, and 547. The principle
difference, from the 7904, is how bright the beam has to be
before I can see the bounce image, and how far from the original
image, the bounce image appears.
Again: What specific phenomenon on the 7904 were you referring to? Maybe the brightness or the high PDA voltage?
Is it not just a gradual difference, as opposed to a specific "7904 phenomenon"?


Trust me...*** I already know you don't***... but high energy electron
beams bounce off of aluminum, gold, phosphor, rock, just about
anything. Because of the PDA, the electrons are dragged back to
the phosphor where they present as a magnified, fuzzy, glowing
image of the original trace.
I added the above emphasis with asterisks. I have no need to trust you on something I know. A less patronizing and arrogant
teacher is a better teacher, trust me... Did I not praise you (and Dennis) enough in my earlier mail?
As said, I'd appreciate you tell me what that specific "phenomenon observed on the 7904" is. I guess you already told us and I missed it but maybe I'll learn from it and please leave out the implied "I'm knowledgeable, you aren't".

Raymond


Re: 7904 excessive shadow/flare

John Ferguson
 

Thank you all for a really  fascinating (and enlightening) discussion.

It appears that Tektronix developed astonishing expertise in the display of data on CRT's.

Has this expertise continued to serve in any industry today or has it become more solutions in search of a problem?


Re: 7904 excessive shadow/flare

Chuck Harris <cfharris@...>
 

Indeed, now show that it doesn't happen with an overly bright
non mesh lens system. I have seen the same stuff on my very old,
and probably now no longer working 513D, which has neither a lens,
nor an aluminized CRT phosphor. It did have a very high anode
voltage...12KV.

I have also seen it happen on a 545, and 547. The principle
difference, from the 7904, is how bright the beam has to be
before I can see the bounce image, and how far from the original
image, the bounce image appears.

The high voltage of the anode accelerates all electrons coming
from the gun to nearly equal speeds. Electron speed is the same
as electron energy. Intensity controls beam current, which is
the electron density of the beam, not the energy of the electrons
in the beam... that is controlled by the anode voltage, and the
length of the beam path.

Anode voltage controls how far the electrons bounce when they
hit the screen. How far they bounce controls how far away they
land from the original spot, for a given angle of beam deflection.

Trust me... I already know you don't... but high energy electron
beams bounce off of aluminum, gold, phosphor, rock, just about
anything. Because of the PDA, the electrons are dragged back to
the phosphor where they present as a magnified, fuzzy, glowing
image of the original trace.

The principal aberration you see with a mesh lens is an indistinct
fuzzy looking spot. This is mostly due to the lens magnifying the
already indistinct fuzzy looking electron beam. The spot is just
a picture of the cathode surface after collimation and focusing...

-Chuck Harris

Raymond Domp Frank wrote:

On Mon, Jul 1, 2019 at 03:32 PM, Chuck Harris wrote:


The 465, and 475, are known to me to have dome mesh lenses,
...I have seen them broken... but neither exhibit the
phenomenon observed on the 7904. The dome mesh lens shows
itself, in these scopes, by a fuzzy, less sharp beam when
compared to a conventional CRT, that has no lens.
I have added 3 images from a 465 showing not just the halo but also some artifacts that are a bit like those on the 7904's CRT, here:
https://groups.io/g/TekScopes/album?id=90746
They are in the main photo album of this topic. Sorry Unclebanjoman, no intention to hijack your album.
The intensity on the 465 must be turned up quite a lot (much more than on the 7904) and it's a bit difficult to photograph but I guess it's visible.
465 Artefacts-1: Slow-moving spot, fluffy stuff, halo etc. *and* "spot moving at much higher speed than main spot, with center at second graticule from left, one division down from the middle. Quite visible in live picture. It looks and moves just like on the 7904 but its brightness is not enough to show up in the sinewave pictures that follow.
465 Artefact-2: A second image, barely visible in picture, as lighter area ("copy" of trace) just left of darker band between first and second graticule from left. It runs through .4 position right of "10", at about -45 degree angle from horizontal.
465 Artefact-3: Shows slightly compressed copy of main trace, mainly visible between first and second graticule horizontally and from seventh to the right. It is smaller in both X and Y, as opposed to the 7904's.

Raymond




Re: OT - can't reach leobodnar site

Vintage Test
 

Works for me too Tim . . .

Cheers,
Mel

--
you can never have enough oscilloscopes, DMMs, valve testers or soldering irons . . .


Re: 7904 excessive shadow/flare

 

On Mon, Jul 1, 2019 at 03:32 PM, Chuck Harris wrote:


The 465, and 475, are known to me to have dome mesh lenses,
...I have seen them broken... but neither exhibit the
phenomenon observed on the 7904. The dome mesh lens shows
itself, in these scopes, by a fuzzy, less sharp beam when
compared to a conventional CRT, that has no lens.
I have added 3 images from a 465 showing not just the halo but also some artifacts that are a bit like those on the 7904's CRT, here:
https://groups.io/g/TekScopes/album?id=90746
They are in the main photo album of this topic. Sorry Unclebanjoman, no intention to hijack your album.
The intensity on the 465 must be turned up quite a lot (much more than on the 7904) and it's a bit difficult to photograph but I guess it's visible.
465 Artefacts-1: Slow-moving spot, fluffy stuff, halo etc. *and* "spot moving at much higher speed than main spot, with center at second graticule from left, one division down from the middle. Quite visible in live picture. It looks and moves just like on the 7904 but its brightness is not enough to show up in the sinewave pictures that follow.
465 Artefact-2: A second image, barely visible in picture, as lighter area ("copy" of trace) just left of darker band between first and second graticule from left. It runs through .4 position right of "10", at about -45 degree angle from horizontal.
465 Artefact-3: Shows slightly compressed copy of main trace, mainly visible between first and second graticule horizontally and from seventh to the right. It is smaller in both X and Y, as opposed to the 7904's.

Raymond

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