1. TekScopes@groups.io
   Date   
Re: Focus on 475 scope

Chuck Harris
 

If your scope intensity double peaks, it could mean
that it is gassy, or it could mean that it has low
emission. Running the CRT will help get the gas
absorbed by the getter, so it may improve.

-Chuck Harris

agaguk_99@hotmail.com wrote:

On Thu, Jan 25, 2018 at 09:38 pm, Chuck Harris wrote:
I'm curious, why are you fixating on the caps?
I know that ceramic capacitor are aging very well. But those 4000v cap wasn't looks like caramic to me so i asked the question. And someone tell me yes check the caps. So i wanted to check those cap :)

The best, easiest way to see if everything is ok
in the focus circuitry is to notice if the focus
pot passes through a single point of best focus.
By that I mean if the pot is fully CCW, the beam
is fuzzy, and as you turn it CW, it gets less and
less fuzzy, until it reaches a point where it
starts to get more and more fuzzy again.
If that happens, you are as good as you are going
to get with the focus circuitry.
Ok,i thing my scope is full working so.


The same should be the case with the astigmatism
control.
yes sameting, working...



If the intensity control "double peaks", then your
problem is a gassy CRT, which will also result in
poor focus/astigmatism.

-Chuck Harris
Thank you chuck, i didn't know that the crt was a problem on that scope. Probably my scope is just working very fine and problem is a bad crt. Thank you all for your answer.
Re: 1L40 Spectrum Analyser

cmjones01
 

On Sun, Jan 21, 2018 at 12:09 pm, cmjones01 wrote:
I'm aware of the 1L40's limitations due to not having an input filter or swept
1st LO, but it should still be useful for what I want. Does anyone else here
have one or any experiences or recollections to share?
Answering my own question, I've just updated the 1L40 page at Tekwiki:
http://proxy.w140.com/tekwiki/wiki/1L40
with a bunch of new photos of the plugin and of it in action, together with a couple of notes about it. Most interestingly, in spite of its published 1.5-40GHz range, it also works perfectly well with signals at its IF of 150-250MHz, which is a handy extra feature.

Chris
Re: Focus on 475 scope

agaguk_99@...
 

On Thu, Jan 25, 2018 at 09:38 pm, Chuck Harris wrote:
I'm curious, why are you fixating on the caps?
I know that ceramic capacitor are aging very well. But those 4000v cap wasn't looks like caramic to me so i asked the question. And someone tell me yes check the caps. So i wanted to check those cap :)

The best, easiest way to see if everything is ok
in the focus circuitry is to notice if the focus
pot passes through a single point of best focus.
By that I mean if the pot is fully CCW, the beam
is fuzzy, and as you turn it CW, it gets less and
less fuzzy, until it reaches a point where it
starts to get more and more fuzzy again.
If that happens, you are as good as you are going
to get with the focus circuitry.
Ok,i thing my scope is full working so.


The same should be the case with the astigmatism
control.
yes sameting, working...



If the intensity control "double peaks", then your
problem is a gassy CRT, which will also result in
poor focus/astigmatism.

-Chuck Harris
Thank you chuck, i didn't know that the crt was a problem on that scope. Probably my scope is just working very fine and problem is a bad crt. Thank you all for your answer.
Re: Any experience with ELECTRONIC LOADS would be appreciated

Michael A. Terrell
 

https://archive.org/details/73-magazine-1976-11 page 179, "The Smoke Tester" has a basic design that uses a driver transistor to reduse the current through the pot.

-----Original Message-----
From: Vince Vielhaber <vev@michvhf.com>
Sent: Jan 25, 2018 8:08 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Any experience with ELECTRONIC LOADS would be appreciated

Why not build one? One or more 2N3055s and a pot. Heat sink, fan and
base resistors as required. I've built many and have even burn-in
tested some 50A power supplies with 'em.

Vince.



On 01/25/2018 05:44 PM, Dennis Tillman W7PF wrote:
Hi Stefan.
I was looking for a cheap, no frills, solution I could start using quickly. I don't need another project to design and build.

What I saw on Ebay were a whole bunch of Chinese electronic loads for pocket change that I could put to use right away and when I'm done put them away until the next time I need one.

I can't recall ever needing a test load in the past. Normally I just use a power resistor. When I saw the ones on Ebay at very reasonable prices I thought it might be time to switch from resistors to an electronic load because it looked more flexible.

Dennis

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of stefan_trethan
Sent: Thursday, January 25, 2018 11:57 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Any experience with ELECTRONIC LOADS would be appreciated

Hi Dennis,

I have not tried the loads on Ebay but use different electronic loads extensively every day.
I have also built several of my own where commercial products did not offer what I needed.

Are you looking at the Chinese loads in a desktop case such as the Maynuo branded one, or something else?
There is information about them here, they are apparently no so bad:
<https://www.eevblog.com/forum/testgear/which-dc-electronic-load-to-get/>;

You can make a load fairly easily, I have always used a beefy mosfet on a heatsink, with a shunt resistor in the source lead.
A simple opamp control loop can do constant voltage/current/resistance control.

Whatever you buy or build, always keep in mind that there is a control loop involved. For certain tests a true resistive load is the only way.

ST




On Thu, Jan 25, 2018 at 8:42 PM, Dennis Tillman W7PF <dennis@ridesoft.com> wrote:
I occasionally have a need for an electronic load. There are many
listed on Ebay. It would appear the Ebay ones are variations on about
10 different designs. Has anyone bought an electronic load off of
Ebay? If so what has been your experience with it.



These are my requirements

1) Voltage as high as possible: it looks like that will be about 100V
from the ones I saw on Ebay

2) Modest current drain of an amp or two. This should be no problem as
all of them do that

3) Power of about 50W. I can add a fan to keep the heatsink cool if
needed.

4) I do not need a USB current load



Dennis Tillman W7PF






--
Michigan VHF Corp. http://www.nobucks.net/ http://www.CDupe.com/
http://www.metalworkingfun.com



Michael A. Terrell
Re: Focus on 475 scope

Tom Gardner
 

On 26/01/18 02:09, agaguk_99@hotmail.com wrote:
Is this mesh dome inside ?
Yes. See a disassembled 465 tube at
https://entertaininghacks.wordpress.com/2016/03/09/rescuing-a-broken-tektronix-465-crt/
Re: Any experience with ELECTRONIC LOADS would be appreciated

Bruce Lane
 

Dennis, keep an eye out for electronic loads from Transistor Devices
(their 'DynaLoad' series). I've used several, and they were a favorite
at Boeing (I actually found mine at Boeing Surplus, back when they still
existed). Very well-built, easy to use, accurate, and TD is very good
with their documentation (schematics either included or available for
the asking).

Most of the ones on Ebay at the moment are, I think, grossly overpriced
(with a few exceptions), but I've also seen them turn up at the Mike &
Key swap meet.

Happy hunting.

On 25-Jan-18 11:42, Dennis Tillman W7PF wrote:

I occasionally have a need for an electronic load. There are many listed on
Ebay. It would appear the Ebay ones are variations on about 10 different
designs. Has anyone bought an electronic load off of Ebay? If so what has
been your experience with it.
--
---
Bruce Lane, ARS KC7GR
http://www.bluefeathertech.com
kyrrin (at) bluefeathertech dot com
"Quando Omni Flunkus Moritati" (Red Green)
Re: Focus on 475 scope

Chuck Harris
 

I'm curious, why are you fixating on the caps?

I have never seen one of the HV caps go bad in a
465 or 475 scope... Triplers, yes, but caps no.

The best, easiest way to see if everything is ok
in the focus circuitry is to notice if the focus
pot passes through a single point of best focus.
By that I mean if the pot is fully CCW, the beam
is fuzzy, and as you turn it CW, it gets less and
less fuzzy, until it reaches a point where it
starts to get more and more fuzzy again.

If that happens, you are as good as you are going
to get with the focus circuitry.

The same should be the case with the astigmatism
control.

If either control doesn't reach a point of best
focus before it runs out of travel, then you have
a problem with resistor tolerance in the focus
divider chain, or the astigmatism divider chain.

Or, possibly an HV supply is out of wack.

If the intensity control "double peaks", then your
problem is a gassy CRT, which will also result in
poor focus/astigmatism.

-Chuck Harris

agaguk_99@hotmail.com wrote:

[Edited Message Follows]

Is this mesh dome inside ? Maybe i could swap the Crt's and see if problem follow the crt. And also swap the caps... i'll let you know
Re: Focus on 475 scope

Chuck Harris
 

The mesh dome is generic, one is as good as the next.
It does not wear out.

The 475 does not have a nice sharp beam. It is inherently
about 1.5 minor divisions wide.

It is at its absolute best when the bandwidth limiter is
turned on to its lowest bandwidth setting.

If the glass screen, or the polycarbonate blast shield,
is dirty, the focus can appear even less sharp than
normal.

The 475A is a little better, as I recall.

-Chuck Harris

agaguk_99@hotmail.com wrote:

Is this mesh dome inside ? Maybe i could swap the Crt's and see if problem follow the crt.
Re: Video of 7612 ADC tube

Dennis Tillman W7pF
 

Hi Michael,

That is a fascinating video. It was really clever how Tek managed to make such fast digitizers when semiconductors could not. I remember clearly when TRW introduced a state of the art 6 bit 20MHz flash digitizer that cost $120. That was the best you could buy in the mid 1970s.

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Michael Dunn
Sent: Thursday, January 25, 2018 6:21 PM
Subject: [TekScopes] Video of 7612 ADC tube

https://www.youtube.com/watch?v=3q97h4O6uII





--
Dennis Tillman W7PF
TekScopes Moderator
Re: Any experience with ELECTRONIC LOADS would be appreciated

bobh@joba.com
 

You just have to decide if you want red or green LED displays or one of each. :-)
Bob.

On 1/25/2018 3:44 PM, Dennis Tillman W7PF wrote:
Hi Stefan.
I was looking for a cheap, no frills, solution I could start using quickly. I don't need another project to design and build.

What I saw on Ebay were a whole bunch of Chinese electronic loads for pocket change that I could put to use right away and when I'm done put them away until the next time I need one.


Dennis
Re: Any experience with ELECTRONIC LOADS would be appreciated

Pete Lancashire
 

Prices fluctuate a lot, just put one in the Ebay search/notify and keep
watch of your emails. If a match is found you will get an email once a day.

One reason for the high prices is 90% of the sellers are clueless what
something sells for vs what the asking price. They see someone posting
a dog turd for $100 and all of sudden there are 50 listings for dog turds
from $50 to $500.

Can take up to a year for it all to settle down.

-pete

On Thu, Jan 25, 2018 at 4:13 PM, Dick <w1ksz@outlook.com> wrote:

A few years ago I picked up a Kikusui PLZ-150 Electronic load. Just looked
at

a couple on e-Pay and got sticker shock. Don't know why they are so
expensive

these days.


73, Dick, W1KSZ


Sent from Outlook<http://aka.ms/weboutlook>;
________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Joe Laffey <
joe@thestable.tv>
Sent: Thursday, January 25, 2018 4:36:52 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Any experience with ELECTRONIC LOADS would be
appreciated

On Thu, 25 Jan 2018, Dennis Tillman W7PF wrote:

I occasionally have a need for an electronic load. There are many listed
on
Ebay. It would appear the Ebay ones are variations on about 10 different
designs. Has anyone bought an electronic load off of Ebay? If so what has
been your experience with it.
I have one of the:

"Constant Current Electronic Load Battery Discharge Capacity Tester 9.99A
60W 30V"

loads from Ebay. It only does 30V (and it will not function above that).

It works very well within its specs, and is a very useful device to have.
All the features work correctly and as advertised.

I know you are looking for somehting higher voltage. If mine is any
indication then a higher voltage one would work great too.

--
73
Joe Laffey
Video of 7612 ADC tube

Michael Dunn
 

Re: Any experience with ELECTRONIC LOADS would be appreciated

redarlington
 

http://www.arachnidlabs.com/reload-pro/

I'm unsure of the voltage, but with the fan kit it's happy running 50W all
day long.

-Bob

On Thu, Jan 25, 2018 at 12:42 PM, Dennis Tillman W7PF <dennis@ridesoft.com>
wrote:

I occasionally have a need for an electronic load. There are many listed on
Ebay. It would appear the Ebay ones are variations on about 10 different
designs. Has anyone bought an electronic load off of Ebay? If so what has
been your experience with it.



These are my requirements

1) Voltage as high as possible: it looks like that will be about 100V
from the ones I saw on Ebay

2) Modest current drain of an amp or two. This should be no problem as
all of them do that

3) Power of about 50W. I can add a fan to keep the heatsink cool if
needed.

4) I do not need a USB current load



Dennis Tillman W7PF
Re: Focus on 475 scope

agaguk_99@...
 
Edited

Is this mesh dome inside ? Maybe i could swap the Crt's and see if problem follow the crt. And also swap the caps... i'll let you know
Re: Any experience with ELECTRONIC LOADS would be appreciated

Kevin Oconnor
 

I bought a Kunkin KL283 dual ch load 80v 15A 300w some time ago. There are higher voltage and current units available. Got it from eBay. Given the price advantage compared to name brands, it works very well.
Sent from kjo iPhone
Re: Any experience with ELECTRONIC LOADS would be appreciated

Vince Vielhaber
 

Why not build one? One or more 2N3055s and a pot. Heat sink, fan and base resistors as required. I've built many and have even burn-in tested some 50A power supplies with 'em.

Vince.

On 01/25/2018 05:44 PM, Dennis Tillman W7PF wrote:
Hi Stefan.
I was looking for a cheap, no frills, solution I could start using quickly. I don't need another project to design and build.

What I saw on Ebay were a whole bunch of Chinese electronic loads for pocket change that I could put to use right away and when I'm done put them away until the next time I need one.

I can't recall ever needing a test load in the past. Normally I just use a power resistor. When I saw the ones on Ebay at very reasonable prices I thought it might be time to switch from resistors to an electronic load because it looked more flexible.

Dennis

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of stefan_trethan
Sent: Thursday, January 25, 2018 11:57 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Any experience with ELECTRONIC LOADS would be appreciated

Hi Dennis,

I have not tried the loads on Ebay but use different electronic loads extensively every day.
I have also built several of my own where commercial products did not offer what I needed.

Are you looking at the Chinese loads in a desktop case such as the Maynuo branded one, or something else?
There is information about them here, they are apparently no so bad:
<https://www.eevblog.com/forum/testgear/which-dc-electronic-load-to-get/>;

You can make a load fairly easily, I have always used a beefy mosfet on a heatsink, with a shunt resistor in the source lead.
A simple opamp control loop can do constant voltage/current/resistance control.

Whatever you buy or build, always keep in mind that there is a control loop involved. For certain tests a true resistive load is the only way.

ST




On Thu, Jan 25, 2018 at 8:42 PM, Dennis Tillman W7PF <dennis@ridesoft.com> wrote:
I occasionally have a need for an electronic load. There are many
listed on Ebay. It would appear the Ebay ones are variations on about
10 different designs. Has anyone bought an electronic load off of
Ebay? If so what has been your experience with it.



These are my requirements

1) Voltage as high as possible: it looks like that will be about 100V
from the ones I saw on Ebay

2) Modest current drain of an amp or two. This should be no problem as
all of them do that

3) Power of about 50W. I can add a fan to keep the heatsink cool if
needed.

4) I do not need a USB current load



Dennis Tillman W7PF






--
Michigan VHF Corp. http://www.nobucks.net/ http://www.CDupe.com/
http://www.metalworkingfun.com
Re: Any experience with ELECTRONIC LOADS would be appreciated

Joe Laffey
 

On Thu, 25 Jan 2018, Dennis Tillman W7PF wrote:

I occasionally have a need for an electronic load. There are many listed on
Ebay. It would appear the Ebay ones are variations on about 10 different
designs. Has anyone bought an electronic load off of Ebay? If so what has
been your experience with it.
Also, if you are inclined to build something. Kerry Wong did a nice video on the topic here:

https://www.youtube.com/watch?v=Vr6YsT403DM&;t=1s


--
73
Joe Laffey
Re: Any experience with ELECTRONIC LOADS would be appreciated

Dick
 

A few years ago I picked up a Kikusui PLZ-150 Electronic load. Just looked at

a couple on e-Pay and got sticker shock. Don't know why they are so expensive

these days.


73, Dick, W1KSZ


Sent from Outlook<http://aka.ms/weboutlook>;
________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Joe Laffey <joe@thestable.tv>
Sent: Thursday, January 25, 2018 4:36:52 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Any experience with ELECTRONIC LOADS would be appreciated

On Thu, 25 Jan 2018, Dennis Tillman W7PF wrote:

I occasionally have a need for an electronic load. There are many listed on
Ebay. It would appear the Ebay ones are variations on about 10 different
designs. Has anyone bought an electronic load off of Ebay? If so what has
been your experience with it.
I have one of the:

"Constant Current Electronic Load Battery Discharge Capacity Tester 9.99A
60W 30V"

loads from Ebay. It only does 30V (and it will not function above that).

It works very well within its specs, and is a very useful device to have.
All the features work correctly and as advertised.

I know you are looking for somehting higher voltage. If mine is any
indication then a higher voltage one would work great too.

--
73
Joe Laffey
Re: Any experience with ELECTRONIC LOADS would be appreciated

Joe Laffey
 

On Thu, 25 Jan 2018, Dennis Tillman W7PF wrote:

I occasionally have a need for an electronic load. There are many listed on
Ebay. It would appear the Ebay ones are variations on about 10 different
designs. Has anyone bought an electronic load off of Ebay? If so what has
been your experience with it.
I have one of the:

"Constant Current Electronic Load Battery Discharge Capacity Tester 9.99A 60W 30V"

loads from Ebay. It only does 30V (and it will not function above that).

It works very well within its specs, and is a very useful device to have. All the features work correctly and as advertised.

I know you are looking for somehting higher voltage. If mine is any indication then a higher voltage one would work great too.

--
73
Joe Laffey
Re: Any experience with ELECTRONIC LOADS would be appreciated

ChuckA
 

I bought one of the Chinese programmable loads, what is called a 3700 series. They show up with various names mine was an Array 3710A. Input voltage up to 360V, current up to 30A, power up to 150W, the model 3711A same but power rating is 300W.

Easy to use and has a computer control software that I never tried. It gets a bit noisy when all 3 fans kick in when you are near max power.

Worked very well on the low voltage high current supplies I was building.

Chuck

On 1/25/2018 5:44 PM, Dennis Tillman W7PF wrote:
Hi Stefan.
I was looking for a cheap, no frills, solution I could start using quickly. I don't need another project to design and build.
What I saw on Ebay were a whole bunch of Chinese electronic loads for pocket change that I could put to use right away and when I'm done put them away until the next time I need one.
I can't recall ever needing a test load in the past. Normally I just use a power resistor. When I saw the ones on Ebay at very reasonable prices I thought it might be time to switch from resistors to an electronic load because it looked more flexible.
Dennis
-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of stefan_trethan
Sent: Thursday, January 25, 2018 11:57 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Any experience with ELECTRONIC LOADS would be appreciated
Hi Dennis,
I have not tried the loads on Ebay but use different electronic loads extensively every day.
I have also built several of my own where commercial products did not offer what I needed.
Are you looking at the Chinese loads in a desktop case such as the Maynuo branded one, or something else?
There is information about them here, they are apparently no so bad:
<https://www.eevblog.com/forum/testgear/which-dc-electronic-load-to-get/>;
You can make a load fairly easily, I have always used a beefy mosfet on a heatsink, with a shunt resistor in the source lead.
A simple opamp control loop can do constant voltage/current/resistance control.
Whatever you buy or build, always keep in mind that there is a control loop involved. For certain tests a true resistive load is the only way.
ST
On Thu, Jan 25, 2018 at 8:42 PM, Dennis Tillman W7PF <dennis@ridesoft.com> wrote:
I occasionally have a need for an electronic load. There are many
listed on Ebay. It would appear the Ebay ones are variations on about
10 different designs. Has anyone bought an electronic load off of
Ebay? If so what has been your experience with it.



These are my requirements

1) Voltage as high as possible: it looks like that will be about 100V
from the ones I saw on Ebay

2) Modest current drain of an amp or two. This should be no problem as
all of them do that

3) Power of about 50W. I can add a fan to keep the heatsink cool if
needed.

4) I do not need a USB current load



Dennis Tillman W7PF



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