Date   
Re: Replacing lamps in a 7B92A timebase

David DiGiacomo
 

On Sun, Nov 11, 2018 at 1:50 PM ef804s tubes <fred.fredenstein@...> wrote:

Hi,
any advice how to procure the 5V lamps and how to replace them in a 7B92A timebase.
Tektronix 150-0048-01 = GE 683AS15 5V 60mA T-1
Readily available on eBay and from the usual Tek parts suppliers.

Plain #683 lamps are fine and available from distributors.

Replacing them is painful and will make you think seriously about
kludging in LEDs :(

Re: Beam modulation on 2465B

BUR
 

The video for confirmation can be found here: https://www.dropbox.com/s/3dxn5k1z9i3snfw/Mod.mp4?dl=0

Re: Beam modulation on 2465B

BUR
 

Problem solved...!
The key was the advice from Chuck to check and verify that "C1972 is a nice low ESR 100uf capacitor." I checked with the RIGOL some chirps, jitters and strange signals appears on the screen not very high amplitude but never less I had some nichicon 100uf /25V and I simply replaced it. And woow.... the modulation is gone away.
I'm very happy with my "new" stable non-modulating trace.

Rolf

Re: Just got a Tektronix 561A, HV woes...

Jack
 

That's a good idea Colin and a small feeler set (e.g. for auto work) only had about 8 leafs and will be not cost as much as a larger one. I thought of fine piano wire
pulled back and forth after being worked through or a pcb drill makes a small access for it but probably there's inadequate access for so that.my response here has to be
circumspect.

One thing with the 'explosion' fear, good thinking in being safe.., vacuums suck inwards so the (essential) use of protective equipment can be supplemented by protective
material placed over the tube itself, to limit bits being reactively 'bounced-out' rather than 'blown' out.. Avoid using WD40 it's not good with electronics .If wanting to lubricate
the feeler blade I'd first try plain water and if that fails, a very fine application of canola or peanut oil with some prevention of it going further than the blade.. Could a suitably
thin cutter be made from a sardine can lid (?) which could also be formed into a 'handle' and say 3/8th inch wide 'cutter'.through using a little dexterity and 'aircraft shears'
then adding some tape around the roll-formed handle (short blade section, long handle section). The old gillette type razor blade broken in half might have some potential if
used with gloves or bound with tape to protect fingers. That exhausts my present imagination but may stimulate brighter minds...
My regards
Ja

Re: Beam modulation on 2465B

BUR
 

I'm not certain that the pictures joined to the replay are added so they are also for download here: https://www.dropbox.com/sh/nqkovo977t7u0v9/AACiDSy6TXUGL_cbxIC0LCPka?dl=0
Rolf

-----Ursprüngliche Nachricht-----
Von: TekScopes@groups.io <TekScopes@groups.io> Im Auftrag von Chuck Harris
Gesendet: Sonntag, 11. November 2018 17:08
An: TekScopes@groups.io
Betreff: Re: [TekScopes] Beam modulation on 2465B

Ok, that was what I was hoping you could show.

You have undoubtedly heard of a Lissajous figure, where the X and Y axis of a scope are driven by two different sinewave sources... instant techy movie.

Well, what you have here is a Lissajous figure where one axis is the time base, and the other is the intensity grid of the CRT.

I would bet that what you are seeing is the EHT oscillator's AC bleeding through into the CRT's cathode/control grid circuit.

The first place I would go is to the A9 HV section, and verify that C1972 is a nice low ESR 100uf capacitor.
The -15V supply goes into a lot of areas, including the Z-axis hybrid. If that capacitor is bad, you will get a lot of 50ish KHz ripple on the -15V line.

You can test C1972 in place by using your Rigol scope, and measuring between P191 pin 8 and chassis ground, and looking at the 50KHz ripple. There will be some, but it should be millivolts, not volts.

Next place I would look is in the DC restorer area. Here I would check the test points 70, 71, 72, 73, and 74, looking for 50KHz anomalies...

If nothing shows up in the above, you have to move to the low voltage signal side of the intensity controls, and the Z-axis hybrid.

Pay attention to the high frequency ripple on the +10V REF supply... particularly frequencies around 1MHZ (J191-P11).

The ripple source could also be the main inverter of the power supply.

-Chuck Harris



BUR wrote:

I got so many very interesting and helpful adevices, so the investigation goes further and further.
I have the possibility to shift the frequency by 1Hz. Doing so i discovered more details about the phenomenon.
Shifting 1 by 1 up the modulation goes from the right side to the left and slows down until it stops at 5Hz up then it starts again but no from left to right. Speeding up until about 18Hz up and then the modulation is gone.
I made a short video to replicate this behaviour here:
https://www.dropbox.com/s/6itcjie8b64a15h/Direction.mp4?dl=0

Replacing lamps in a 7B92A timebase

ef804s tubes
 

Hi,
any advice how to procure the 5V lamps and how to replace them in a 7B92A timebase.

Thanks,

Fred

Re: Beam modulation on 2465B

BUR
 

I couldn't wait. Just checked that "C1972 is a nice low ESR 100uf capacitor" with the scope. P191 pin 8 and chassis ground shows the image added.
It's not much but finally I have some new nichicon 100uf /25V and I will replace it. It's not a big deal.

Rolf



-----Ursprüngliche Nachricht-----
Von: TekScopes@groups.io <TekScopes@groups.io> Im Auftrag von Chuck Harris
Gesendet: Sonntag, 11. November 2018 17:08
An: TekScopes@groups.io
Betreff: Re: [TekScopes] Beam modulation on 2465B

Ok, that was what I was hoping you could show.

You have undoubtedly heard of a Lissajous figure, where the X and Y axis of a scope are driven by two different sinewave sources... instant techy movie.

Well, what you have here is a Lissajous figure where one axis is the time base, and the other is the intensity grid of the CRT.

I would bet that what you are seeing is the EHT oscillator's AC bleeding through into the CRT's cathode/control grid circuit.

The first place I would go is to the A9 HV section, and verify that C1972 is a nice low ESR 100uf capacitor.
The -15V supply goes into a lot of areas, including the Z-axis hybrid. If that capacitor is bad, you will get a lot of 50ish KHz ripple on the -15V line.

You can test C1972 in place by using your Rigol scope, and measuring between P191 pin 8 and chassis ground, and looking at the 50KHz ripple. There will be some, but it should be millivolts, not volts.

Next place I would look is in the DC restorer area. Here I would check the test points 70, 71, 72, 73, and 74, looking for 50KHz anomalies...

If nothing shows up in the above, you have to move to the low voltage signal side of the intensity controls, and the Z-axis hybrid.

Pay attention to the high frequency ripple on the +10V REF supply... particularly frequencies around 1MHZ (J191-P11).

The ripple source could also be the main inverter of the power supply.

-Chuck Harris



BUR wrote:

I got so many very interesting and helpful adevices, so the investigation goes further and further.
I have the possibility to shift the frequency by 1Hz. Doing so i discovered more details about the phenomenon.
Shifting 1 by 1 up the modulation goes from the right side to the left and slows down until it stops at 5Hz up then it starts again but no from left to right. Speeding up until about 18Hz up and then the modulation is gone.
I made a short video to replicate this behaviour here:
https://www.dropbox.com/s/6itcjie8b64a15h/Direction.mp4?dl=0

Re: Just got a Tektronix 561A, HV woes...

Jack
 

Hi Albert..thanks for that, I hadn't thought it through to that extent, made the comment, I was thinking only of a circuitous circuit from one pin through the filament "plus" to earth if earth is
used . Only mA would be drawn at that resistance which would make heating a slow exercise. You wrote something.... "discontinuity breaks'.... that took me back to a fault from long ago....
It might sound puerile but...that's a risk I'll take...I doubt one could solder-suck them to get 'deep' but one can poke fine solder into the pins a bit ......I'd resolder the filament pins....nothing
lost, something maybe gained..

Jack

Re: Just got a Tektronix 561A, HV woes...

Brenda
 

Hello,

I should have mentioned that my 561A has the all glass style. That's why I was mentioning the 4 cushions that are inside the CRT shield not wanting to let the CRT out. My other working 561A is also all glass, and I am pretty sure that it has the rubber shock ring around the CRT.

Brenda

Re: Just got a Tektronix 561A, HV woes...

Colin Herbert
 

Just a suggestion, but I had a similar problem getting the CRT out of a Cossor 1039M. Ok, it wasn't the mount around the CRT face, but the rear clamp had a rubbery gasket-type thing which had perished and adhered itself to the glass of the CRT. Looking for something thin to break the adherence, I tried a metal feeler-gauge. This was thin enough to slide in without undue pressure on the CRT and was stiff enough to prise its way between CRT and gasket.

I suppose this depends on having a set of feeler-gauges - does anyone do DIY on cars any more?

Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Albert Otten
Sent: 11 November 2018 18:43
To: TekScopes@groups.io
Subject: Re: [TekScopes] Just got a Tektronix 561A, HV woes...

Which type of CRT is it? I ask since in a 561A manual there are instructions how to replace the old glass style by the ceramic style.
The 564 and 561B manuals contain exploded views in which you can see how huge the shockmount ring around the CRT face is. I have experienced in 564s with ceramic CRT that you need a lot of patience to peel out the CRT+ring. I used a combination of pressure from the rear side, some jiggling and IIRC even a screw driver like lever between rubber and surroundings.

Albert

On Sun, Nov 11, 2018 at 07:12 PM, Harvey White wrote:


On Sun, 11 Nov 2018 10:02:13 -0800, you wrote:

Hello Xnke, I would certainly be interested in the spare CRT and the scope
cart since I only have 1 for now. But my main concern is getting the old CRT
out of the 561A. Something has a death grip in the front of the CRT I am
assuming the cushions that I read in the manual. I am getting frustrated and I
certainly don't want the CRT to explode in my face. Getting the CRT out
safely is my next step. Maybe someone will have an idea?

Likely the clamps, they tend to stick. For the sake of paranoia, wear
a long sleeve shirt, and find one of the woodworking style of face
protectors (Harbor Freight can help if nearby). Not too much
experience in scope CRT removal, but some in old TV CRT removal. I'd
wait for the experts. Makes you wonder if WD40 might help (LIMITED
AMOUNTS! <grin>)

Harvey

Re: Just got a Tektronix 561A, HV woes...

Albert Otten
 

Which type of CRT is it? I ask since in a 561A manual there are instructions how to replace the old glass style by the ceramic style.
The 564 and 561B manuals contain exploded views in which you can see how huge the shockmount ring around the CRT face is. I have experienced in 564s with ceramic CRT that you need a lot of patience to peel out the CRT+ring. I used a combination of pressure from the rear side, some jiggling and IIRC even a screw driver like lever between rubber and surroundings.

Albert

On Sun, Nov 11, 2018 at 07:12 PM, Harvey White wrote:


On Sun, 11 Nov 2018 10:02:13 -0800, you wrote:

Hello Xnke, I would certainly be interested in the spare CRT and the scope
cart since I only have 1 for now. But my main concern is getting the old CRT
out of the 561A. Something has a death grip in the front of the CRT I am
assuming the cushions that I read in the manual. I am getting frustrated and I
certainly don't want the CRT to explode in my face. Getting the CRT out
safely is my next step. Maybe someone will have an idea?

Likely the clamps, they tend to stick. For the sake of paranoia, wear
a long sleeve shirt, and find one of the woodworking style of face
protectors (Harbor Freight can help if nearby). Not too much
experience in scope CRT removal, but some in old TV CRT removal. I'd
wait for the experts. Makes you wonder if WD40 might help (LIMITED
AMOUNTS! <grin>)

Harvey

Re: Just got a Tektronix 561A, HV woes...

Harvey White
 

On Sun, 11 Nov 2018 10:02:13 -0800, you wrote:

Hello Xnke, I would certainly be interested in the spare CRT and the scope cart since I only have 1 for now. But my main concern is getting the old CRT out of the 561A. Something has a death grip in the front of the CRT I am assuming the cushions that I read in the manual. I am getting frustrated and I certainly don't want the CRT to explode in my face. Getting the CRT out safely is my next step. Maybe someone will have an idea?
Likely the clamps, they tend to stick. For the sake of paranoia, wear
a long sleeve shirt, and find one of the woodworking style of face
protectors (Harbor Freight can help if nearby). Not too much
experience in scope CRT removal, but some in old TV CRT removal. I'd
wait for the experts. Makes you wonder if WD40 might help (LIMITED
AMOUNTS! <grin>)

Harvey




Re: Soldering tunnel diodes

Harvey White
 

On Sun, 11 Nov 2018 10:50:37 -0500, you wrote:

Hi Harvey,
Assuming you iron's tip is small enough to use on a TD just connect your
soldering iron to a lamp dimmer to cool the tip. Simple!
Yep, weren't me who had the problem. I have a few variable temp
irons, and I do have a metcal (so no variac!). I do have various
temperature metcal tips, without which I would not be (to quote Mr.
Churchill).

Thermaltronics is the company that makes replacement/equivalent tips.
I have a few, they are cheaper than Metcal (but come in less
varieties).

Harvey


Dennis Tillman W7PF

-----Original Message-----
From: Harvey White
Sent: Saturday, November 10, 2018 1:05 AM
Subject: Re: [TekScopes] Soldering tunnel diodes

On Fri, 09 Nov 2018 11:49:02 -0800, you wrote:

Hey all,

While I was probing the tunnel diode in my 556, one lead of the tunnel
diode popped off the board. It's the kind in the gold-colored metal case,
rather than the little epoxy blob. It tested spot on with a curve tracer
after popping off the board, so it's still okay. I want to know the best
way
to resolder it to the board without damage. Any suggestions? There's not
really enough room for a heat sink clamp since it uses very short leads. I
suspect a little silver epoxy would be okay, but this makes it really
nasty
to remove if that should ever be required. My soldering iron is a metcal
so
it only does one temperature, so I'd prefer not to have to get an iron
just
for doing low melt solder. Will long needle nose pliars be okay as a heat
sink along with standard solder?

Metcal has tips in at least 3 temperatures. There's another company which
makes metcal compatible tips at lower prices. Check amazon.

and I suspect that the pliers would be ok, but I'll defer to people who
use
tunnel diodes.

Oh, and you may wish to get eutectic solder for just such a thing (as well
as SMT parts if you ever use them. Resistors, capacitors, LEDs and diodes
do quite well.

Harvey

Re: Just got a Tektronix 561A, HV woes...

Brenda
 

Hello Xnke, I would certainly be interested in the spare CRT and the scope cart since I only have 1 for now. But my main concern is getting the old CRT out of the 561A. Something has a death grip in the front of the CRT I am assuming the cushions that I read in the manual. I am getting frustrated and I certainly don't want the CRT to explode in my face. Getting the CRT out safely is my next step. Maybe someone will have an idea?

Re: Soldering tunnel diodes

Mark Goldberg
 

Dennis:
Metcals use RF to heat the tip and are self regulating at the tip so this
won't work with them. You have to use a lower temp tip.

http://www.okinternational.com/metcal/english/globalnavigation/applications/hand-soldering/what-is-smartheat

Evan:
That being said, they heat up rapidly and keep their temp with load so
usually you can solder more quickly. I have used the medical type locking
hemostats to clamp off as a heatsink, add some flux, and just touch the
iron quickly on similar parts. I haven't soldered tunnel diodes though.

I have extra Metcal tips in various sizes and temps. Contact me off list if
you need a different one than you have.

Regards,

Mark




On Sun, Nov 11, 2018 at 8:50 AM Dennis Tillman W7PF <@Dennis_Tillman_W7PF>
wrote:

Hi Harvey,
Assuming you iron's tip is small enough to use on a TD just connect your
soldering iron to a lamp dimmer to cool the tip. Simple!
Dennis Tillman W7PF

-----Original Message-----
From: Harvey White
Sent: Saturday, November 10, 2018 1:05 AM
Subject: Re: [TekScopes] Soldering tunnel diodes

On Fri, 09 Nov 2018 11:49:02 -0800, you wrote:

Hey all,

While I was probing the tunnel diode in my 556, one lead of the tunnel
diode popped off the board. It's the kind in the gold-colored metal case,
rather than the little epoxy blob. It tested spot on with a curve tracer
after popping off the board, so it's still okay. I want to know the best
way
to resolder it to the board without damage. Any suggestions? There's not
really enough room for a heat sink clamp since it uses very short leads.
I
suspect a little silver epoxy would be okay, but this makes it really
nasty
to remove if that should ever be required. My soldering iron is a metcal
so
it only does one temperature, so I'd prefer not to have to get an iron
just
for doing low melt solder. Will long needle nose pliars be okay as a heat
sink along with standard solder?

Metcal has tips in at least 3 temperatures. There's another company
which
makes metcal compatible tips at lower prices. Check amazon.

and I suspect that the pliers would be ok, but I'll defer to people who
use
tunnel diodes.

Oh, and you may wish to get eutectic solder for just such a thing (as
well
as SMT parts if you ever use them. Resistors, capacitors, LEDs and
diodes
do quite well.

Harvey


--
Dennis Tillman W7PF
TekScopes Moderator



Re: Beam modulation on 2465B

BUR
 

Perfect, many thanks for the precise analyse and the guide for localising the problem.
It’s awesome the help we can have from the expert on this forum.
I know what kind of job I have next week.

Once more, thanks a lot

Rolf

-----Ursprüngliche Nachricht-----
Von: TekScopes@groups.io <TekScopes@groups.io> Im Auftrag von Chuck Harris
Gesendet: Sonntag, 11. November 2018 17:08
An: TekScopes@groups.io
Betreff: Re: [TekScopes] Beam modulation on 2465B

Ok, that was what I was hoping you could show.

You have undoubtedly heard of a Lissajous figure, where the X and Y axis of a scope are driven by two different sinewave sources... instant techy movie.

Well, what you have here is a Lissajous figure where one axis is the time base, and the other is the intensity grid of the CRT.

I would bet that what you are seeing is the EHT oscillator's AC bleeding through into the CRT's cathode/control grid circuit.

The first place I would go is to the A9 HV section, and verify that C1972 is a nice low ESR 100uf capacitor.
The -15V supply goes into a lot of areas, including the Z-axis hybrid. If that capacitor is bad, you will get a lot of 50ish KHz ripple on the -15V line.

You can test C1972 in place by using your Rigol scope, and measuring between P191 pin 8 and chassis ground, and looking at the 50KHz ripple. There will be some, but it should be millivolts, not volts.

Next place I would look is in the DC restorer area. Here I would check the test points 70, 71, 72, 73, and 74, looking for 50KHz anomalies...

If nothing shows up in the above, you have to move to the low voltage signal side of the intensity controls, and the Z-axis hybrid.

Pay attention to the high frequency ripple on the +10V REF supply... particularly frequencies around 1MHZ (J191-P11).

The ripple source could also be the main inverter of the power supply.

-Chuck Harris



BUR wrote:

I got so many very interesting and helpful adevices, so the investigation goes further and further.
I have the possibility to shift the frequency by 1Hz. Doing so i discovered more details about the phenomenon.
Shifting 1 by 1 up the modulation goes from the right side to the left and slows down until it stops at 5Hz up then it starts again but no from left to right. Speeding up until about 18Hz up and then the modulation is gone.
I made a short video to replicate this behaviour here:
https://www.dropbox.com/s/6itcjie8b64a15h/Direction.mp4?dl=0

Re: ( the price of) printed original manuals

Chuck Harris
 

Hi Dennis,

That is only partly true. The real reason is the Universal
Postal Union UPU), which was established by the Treaty of Bern
in 1874, and all of the subsequent changes to the UPU that
happened in 1969, 2016, ... and 2018.

See <https://en.wikipedia.org/wiki/Universal_Postal_Union>

for a more complete treatment than should be discussed on tekscopes.

Everything is now changed, however, as the US has quit the UPU,
and is refactoring its light parcel postage agreements with the
rest of the world, and especially China.

And for a more complete treatment of the US's quitting UPU than
should be discussed on tekscopes:

See
<https://www.postalandparceltechnologyinternational.com/opinion/is-trumps-decision-to-quit-the-upu-a-bad-thing.html>

The free China shipping will soon be a thing of the past.

Please let's not continue this thread to any great degree. It is
only very loosely related to Tekscopes, in that we often engage in
international shipping to ship scopes and parts.


-Chuck Harris

Dennis Tillman W7PF wrote:

Hi Kevin,
The Chinese government is subsidizing international postal shipments on
purpose which is why shipping to the USA is free from China in almost all
cases. Their purpose is to get us addicted to their products and I can
personally attest to the fact that it works.

Dennis Tillman W7PF

-----Original Message-----
From: Kevin Oconnor
Sent: Saturday, November 10, 2018 8:15 PM
Subject: Re: [TekScopes] ( the price of) printed original manuals

USPS shipping.... U picked an open wound with me. US small mail customers
are getting screwed by international trade agreements. Cheapest <13oz 1st
class parcel for me is ~$5-7 to lower 48.
I get a epacket from China for <$2. Amazon delivers, via USPS, a $5 item
in
an 6x6x10 in box for free. And the USPS is still going broke.

Sent from kjo iPhone


Re: Just got a Tektronix 561A, HV woes...

Albert Otten
 

On Sun, Nov 11, 2018 at 04:19 AM, Jack wrote:


My thoughts, though you are in safe hands it seems, were presuming you are
not somehow measuring personal resistance,...of which you would be acutely
aware...'is there a possibility the heater is contacting another CRT
element?'....In everyday tubes, just as an example, heater-cathode contact can
occur.

Is it worth looking around for a replacement/spare CRT anyway...sooner or
later you might need it and it may help in testing. Perhaps ask the vendor to
measure filament resistance before going ahead. My Regards

--
Jack
In this case a short between heater and cathode would do no harm in that there would be zero voltage across the neons. I would be curious to check for a short between the grid (pin 3) and one of the unblanking plates (pins 6 and 7). Sometimes a short can be blown away with the charged capacitor trick.
Since the CRT neck was found to be warm in one occasion I would also try an external 6 V supply between pins 1 and 14. It's possible that a discontinuity breaks down when 6 V is applied (in stead of the probably much smaller DMM voltage for resistance measurements).

Albert

Re: Beam modulation on 2465B

Chuck Harris
 

Ok, that was what I was hoping you could show.

You have undoubtedly heard of a Lissajous figure,
where the X and Y axis of a scope are driven by two
different sinewave sources... instant techy movie.

Well, what you have here is a Lissajous figure where
one axis is the time base, and the other is the
intensity grid of the CRT.

I would bet that what you are seeing is the EHT
oscillator's AC bleeding through into the CRT's
cathode/control grid circuit.

The first place I would go is to the A9 HV section,
and verify that C1972 is a nice low ESR 100uf capacitor.
The -15V supply goes into a lot of areas, including the
Z-axis hybrid. If that capacitor is bad, you will get
a lot of 50ish KHz ripple on the -15V line.

You can test C1972 in place by using your Rigol scope,
and measuring between P191 pin 8 and chassis ground, and
looking at the 50KHz ripple. There will be some, but
it should be millivolts, not volts.

Next place I would look is in the DC restorer area. Here
I would check the test points 70, 71, 72, 73, and 74,
looking for 50KHz anomalies...

If nothing shows up in the above, you have to move to the
low voltage signal side of the intensity controls, and
the Z-axis hybrid.

Pay attention to the high frequency ripple on the +10V REF
supply... particularly frequencies around 1MHZ (J191-P11).

The ripple source could also be the main inverter of the
power supply.

-Chuck Harris



BUR wrote:

I got so many very interesting and helpful adevices, so the investigation goes further and further.
I have the possibility to shift the frequency by 1Hz. Doing so i discovered more details about the phenomenon.
Shifting 1 by 1 up the modulation goes from the right side to the left and slows down until it stops at 5Hz up then it starts again but no from left to right. Speeding up until about 18Hz up and then the modulation is gone.
I made a short video to replicate this behaviour here: https://www.dropbox.com/s/6itcjie8b64a15h/Direction.mp4?dl=0

Re: 2712 N connector source.

 

Randy,
Jack is referring to one of our newer members, Dinos of Qservice. His contact information is
Dinos
Qservice Electronics
https://www.qservice.tv/

I have bought Tek things from Dinos for many years and I can personally recommend him.

You might also try Walter and Susan Shawlee at Sphere Electronics. They are also someone I highly recommend.
http://www.sphere.bc.ca/

Dennis Tillman W7PF

-----Original Message-----
From: Jack
Sent: Sunday, November 11, 2018 12:34 AM
Subject: Re: [TekScopes] 2712 N connector source.
Hi, a chap who carries a lot of gear is at "qservice-electronics" in
Greece...advertises parts in eBay under the various CRO types and is a
decent bloke.
Tell him Jack from Australia referred you if you like....he's been a great
help to me. This is a random eBay number which would help you find his
store 232997425041. He's a straight shooter unlike some recent others with
Tektronix so I feel ok to receommend him.
--
Jack



--
Dennis Tillman W7PF
TekScopes Moderator