开云体育

Hi Kurt :
Thanks a lot for your information !!!
RegardTony CheungNOV 6 2019

I likely have a means of reading, archiving and programming a chip.

Can you give me a more complete description of the device? Manufacturer, a
picture of the chip, ect.?

Joe

Craig,

Hate to see you go, but I also understand your reason for leaving. I have enjoyed reading your comments and learning from you.

Best of luck going forward.
--
Michael Lynch
Dardanelle, AR

You will be missed.

Vince.

--
K8ZW

Hi all



I've been thinking about this for quite a while. But I think after 18 years on Tekscopes it is
finally time to sign off. In part it is because I think I have said all there is that I can possibly
say on Tekscopes, and in part because I just figured out that I have posted over 4,600 times - an
exceptionally depressing number, even more so when it represents 14% of all posts to Tekscopes ever.
That is one in every seven posts, heaven help us all, that I reckon to be over 800 hours of typing,
not counting the thinking time.



So to the many people who are on this list who have helped me to figure out problems in my stable of
Tektronix gear - my heartfelt thanks. There have been notable assistance above and beyond the call -
as an example, while describing a particular fault in my 7854, one of the list members disconnected
the sampling bridge in his own unit to mimic the fault! And yes, my vertical sampling bridge was
indeed toast. You have all been an inspiration, and I hope that some of you think of me as a friend.
I also hope that over the years I have been able to contribute something to others.



Anyhow - cheers all



Signing off



Craig Sawyers

On Wed, Nov 6, 2019 at 12:08 AM, Dennis Tillman W7PF wrote:

Hi Raymond,
You're a stickler for the specs. You are correct on both accounts but I
believe I was able to work around them:
1) The bandwidth is 350MHz but I use a 7A29 in the horizontal slot which
probably accounted for my impression that I got greater than 350MHz.
2) Option 2 (phase compensation), which is not a common option, would be
necessary for some applications but I did not need it. I use a 7A29 Option 4
Variable Delay plugin to adjust phase if I need to.

Hi Dennis,
Thanks for that information.
I guess I should have made the following disclosure:
About a year ago, I acquired a 7104 with option 2. My first 7104 didn't have that.

This 7104 with 2 x 7A29 (one has option 4) and a 7B15 (no 7B10) is in an absolutely pristine condition: The painted parts of the case are still silky dull all over, not the local leathery look that develops from touching, even the bent and cut edges are still covered in paint, no Al shining through. It definitely has *not* been repainted, as can be seen when inspecting the inside of the panels and it matches the overall condition. No dust, it has obviously been stored in the dark (no yellowing of buttons, no paint abrasion of printed texts on buttons). Very late series. And of course, the MCP CRT has virtually no traces of use. The inside of the instrument looks absolutely new.
Obviously, a like-new service manual was included.
The instrument was "used" in a university-affiliated lab, where it was kept in a closet, only to be brought out when necessary for some job and returned immediately afterward. I guess they realized the cost and vulnerability of the toy. The only things missing were the original cardboard box and packaging materials....
I'm keeping it in a dark place that's actually more like a vault...

Re. the OCXOVT-BV5 ovenized oscillator: I also bought a few (4) some years ago and used one as the time base in my 2252 portable 'scope. In that 'scope the PLL circuits had failed. A simple phase detector built with a 74LS86 EXOR gate as an external replacement sorted that out.

Raymond

Here is the 120-0360-00 drawing:

Another great piece of work, Dennis! Thanks for uploading that.



Craig



From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Notification
Sent: 05 November 2019 22:48
To: [email protected]
Subject: [TekScopes] New file uploaded to [email protected]



Hello,

This email message is a notification to let you know that the following files have been uploaded to the Files area of the [email protected] <mailto:[email protected]> group.

* /Tek 7D11 </g/TekScopes/files/Tek%207D11%20&%207D14%20&%207D15%20OCXO.pdf> & 7D14 & 7D15 OCXO.pdf

Uploaded By: Dennis Tillman W7PF <dennis@... <mailto:dennis@...> >

Description:
Replacement OCXO (Oven Controlled Crystal Oscillator) for the XO (Crystal Oscillator) in the 7D11, 7D14, and 7D15 plugins by Dennis Tillman W7PF

Cheers,
The Groups.io Team

Agreed - that was my experience with the RA17. Of course I have a 130 LC meter (no surprise there!)
and the only thing I had to do was replace the smoothing electrolytic, which had gone down with the
"Sprague twist-lock disconnection issue". Haven't fired it up in quite a while; must do so and make
sure it is still alive.

Craig

Here is the 120-197 drawing:

Chuck

I recall more than a few instances where you willfully dragged a thread down a direction that the
Subject didn't expose...

OK - you got me fair and square. I *hope* I changed the topic line ;-)

And, if it "happens all the time", maybe it is actually normal for the group, rather than an
outlier, as
you suppose.

-Chuck Harris

I really have no problem at all with a conversation going off in another direction, but if we do so,
we really ought to strive to change the subject line to reflect that.

That is as much a reminder to myself to make sure I do so rigorously with my own posts when I myself
subvert a thread!

Craig

Hi,
where can I find the error codes for the7854 displayed by the vertical and horizontal mode switches.
In my case all vertical mode switches are lit and Chop and B on the horizontal mode switches.
--
Best regards,

Fred S.

You probably don't want to take the chance, but if you can't find anyone local to make the copy, you are welcome to send it to me and I would be happy to copy it for you. Also, I haven't checked for compatibility, but I have a couple of AM27C64-120DC IC's that I could program and send along, as well.
GerryR
KK4GER

Hi Raymond,
You're a stickler for the specs. You are correct on both accounts but I believe I was able to work around them:
1) The bandwidth is 350MHz but I use a 7A29 in the horizontal slot which probably accounted for my impression that I got greater than 350MHz.
2) Option 2 (phase compensation), which is not a common option, would be necessary for some applications but I did not need it. I use a 7A29 Option 4 Variable Delay plugin to adjust phase if I need to.

I have owned three ARGOSystems AS210 Rubidium (Rb) Standards for over 10 years. They are very interesting systems. They were designed to fit into a TM515 Traveler Main Frame so they would be portable and could be used in the field whenever it was necessary to make precise measurements based on an accurate frequency standard. The TM515 is gutted then the Rb oscillator is installed along side a new smaller power than the original TM515 supply. A fan is added to keep everything cool. The rear interface board was replaced with a custom one. All of the plugins phase lock to the Rb oscillator. The one that is of particular importance to this story is the AS-210-03 Frequency Generator which generates several fixed reference frequencies (1MHz, 10MHz, 50MHz, 100MHz, 200MHz, ... 500MHz).

The Achilles heel of the system became apparent when I asked John Miles to evaluate the Rb Oscillator - the heart of the system. Its Phase Noise performance was poor. In other words it has a lot of phase noise.

One day I decided to see if it would be possible to view a 100MHz Lissajous circle from the AS-210-03 Frequency Generator on a 7000 scope in X/Y mode. I first tried this on a 7603. I was puzzled when it didn't work. Next I tried it on a 7704A which was a 200MHz scope so I expected it would work. The result was the same. Scratching my head I tried it on a 7854, a 400MHz scope. The results were no better. There was no horizontal deflection. That is when I discovered every Tek 7000 scope (but one) has a very limited horizontal capability. I always assumed the horizontal signal chain had to be as fast as the vertical but that was because I never thought about it. The horizontal bandwidth / sensitivity is lower due to the deflection plates being further forward from the vertical deflection plates. Checking the specs of several scopes confirmed the horizontal amplifier was not fast except for the 7104's 350MHz Horizontal BW. Now I had a way to do this little experiment.

First I adjusted all three of my ARGOSystems AS210s to the output of my Thunderbolt based GPS Frequency Receiver (which I own thanks to John Miles). Once each ARGOSystems AS210 was fine tuned to match the GPS reference I disconnected it. The AS210s were each running on their own at this point but they are stable to 10^-9.

Next I fed the output of the AS-210-03 Frequency Generator in the FIRST ARGOSystems AS210 to the 7A29 vertical amplifier of the 7104. Then I fed the AS210-03 Frequency Generator in the SECOND ARGOSystems AS210 to the 7A29 horizontal amplifier of the 7104. Both ARGOSystems were completely independent. I started out at 100MHz on both AS210-03s and got a perfect Lissajous circle (with some phase noise which added fuzz to it). As I increased the frequency to 200MHz, then 300MHz, and 400MHz the circle got progressively fuzzier due to the phase noise but it was still a circle. At 500MHz the horizontal gain began to drop a noticeable amount which was easy to fix by increasing the gain of the 7A29 to 200mV/Div in each axis.

The phase noise fuzz was now the dominant thing on the screen. It almost obscured the circle. But the circle was still there and I could see the phase slowly starting to shift between the two Rb standards. Each full turn of the circle represented a phase shift of 360 degrees. This was occurring every 2 to 5 seconds. From that I concluded the Rb standards were within ~1/2Hz of each other on average at 500MHz. That is on the order of 500 x 10^6 / 0.5 = 10 ^9 or 1 part in a billion over a 5 second period.

I didn't stop there. I put two 7D14 Frequency Counter plugins into the 7104 to measure the 500MHz frequency going to each 7A29. The first time I did this I was very disappointed to see the 7D14 crystal time base stability was only good to the first 6 on-screen digits but it displays a full 8 digits. I was not going to accept that. I found 8 OCXOVT-BV5 10MHz OCXOs for $10 each on eBay about 6 years ago that were 100X better than the original 7D14 crystal. Since the same crystal is used in the 7D11, 7D14, and 7D15 I designed a simple drop-in replacement PC Board and built 8 of them as replacements in my plugins. I put a detailed description of what this little side project was all about up on TekScopes. It is in the files section. It is called "Tek 7D11 & 7D14 & 7D15 OCXO.pdf" and it is at:

/g/TekScopes/files/Tek%207D11%20&%207D14%20&%207D15%20OCXO.pdf

Dennis Tillman W7PF

The old silver mica caps were used in lots of antique AM broadcast radios (1930s -1960s), particularly in the IF stages. They were known to cause a phenomenon called "thunderstorming", which, even when receiving a strong station, caused a random loud static that sounded exactly like a nearby thunderstorm. This was caused by the silver deposits on the surfaces of the mica layers actually migrating toward the edges of the mica slabs. The high voltages used in those old tube radios drew the silver atoms toward the edges of the mica, and when enough silver migrated to the edges, there was enough current leakage in the capacitor to cause the "static" noise.
Of course, the only solution was to replace the old micas with new ones and retune the IF stages.

Spoken from experience {:>)
Dave M

Craig,

I recall more than a few instances where you willfully dragged
a thread down a direction that the Subject didn't expose...

Why is it ok when you do it?

And, if it "happens all the time", maybe it is actually normal
for the group, rather than an outlier, as you suppose.

-Chuck Harris


Craig Sawyers wrote:

Hello,

This email message is a notification to let you know that the following files have been uploaded to the Files area of the [email protected] group.

• /Tek 7D11 & 7D14 & 7D15 OCXO.pdf

Uploaded By: Dennis Tillman W7PF <dennis@...>

Description:
Replacement OCXO (Oven Controlled Crystal Oscillator) for the XO (Crystal Oscillator) in the 7D11, 7D14, and 7D15 plugins by Dennis Tillman W7PF

Cheers,
The Groups.io Team

Well, to each his own.? Keeps things interesting! ;)JimSent from my Verizon, Samsung Galaxy smartphone

if you lift one leg of C22 (towards V15A), it will isolate the variable
oscillator, and then you can troubleshoot it without involving other parts
of the circuit.
Same with C17 - the amplifier for variable oscillator - where you can
disconnect it from mixer and check its input and output.
Check V4 heater voltage, and I hope C402 was checked. I cant recollect
precisely, but I had issues around these components as well.
if you want I can check the DC bias voltages for V4 and update you over
weekend.


On Tue, Nov 5, 2019 at 1:48 PM Bob Albert via Groups.Io <bob91343=
[email protected]> wrote:

Thanks but that's not it. The zero adjust controls work okay and the
problem is simply that the variable oscillator doesn't oscillate. I have a
tiny signal from it whose frequency can be varied a bit with the tuning
slug. But it's nowhere near enough to drive the mixer.
Bob
On Tuesday, November 5, 2019, 11:54:04 AM PST, Rajesh VS <
rajeshvs@...> wrote:

Bob,in case it helps..my LC130 was misbehaving when I acquired it, and
the cause was a broken solder joint around the Zero adjust controls (front
Panel) . Don't recollect if it was in the fine or coarse control.
Location is top left in the pic -




On Tue, Nov 5, 2019 at 11:00 AM Bob Albert via Groups.Io <bob91343=
[email protected]> wrote:

Yes I am aware of many of the failings of various capacitor types.
However, I am not convinced that the problem in this circuit is caused

by a

poorly behaving capacitor. I will once again attempt to measure voltages
and even a few components to see where something isn't right.
For now, though, my attention is directed elsewhere. I have other means
of making measurements that the 130 can do, so my interest is only to

have

some fun with the unit. If I never get it working, it still is a vehicle
for education. The lowest range, 0 - 3 pF, intrigues me but I can make
those measurements with the Q meter if need be. I have a few 2 pF, I
think, capacitors that I want to characterize. They are the ceramic
dogbone style.
I also have a box of variable capacitors but those are easy. It pains me
to have these, as I have no projected use for them and they are almost
works of art, with the lovely bearings and shafts and other moving parts.
Back in the day, one might build an amplifier or tuner, but I don't need
either. So I will stuff them into the closet and let my heirs dispose of
it all, as they will be obliged to do with all my precious possessions.

It

might be prudent for some local enthusiast to make friends with me and my
family in anticipation of this event.
Bob
On Tuesday, November 5, 2019, 10:26:50 AM PST, Richard Knoppow <
dickburk@...> wrote:

There are two kinds of mica caps, silvered mica and plain
mica. Silver mica of a certain period suffer from something
called silver mica desease, probably due to moisture penetration
through the Bakelite casings. More modern epoxy dipped caps do
not seem to have this problem and it is only occasionally found
on the Bakelite type. It results in the cap becoming unstable,
sometimes jumping in value and sometimes having "scintillation"
or rapid variations. One should be aware of it but mica caps do
not have the predictable degradation with time of paper caps. The
other type of mica caps, usually found a HV transmitting caps,
are made of stacks of mica dielectric and foil pressed together
and held under pressure. They seem to be nearly perfectly
reliable but silver mica have better HF characteristics.
Ceramic caps depend on the type of ceramic. Those made with
high K material do age and change value. They also have
considerable voltage coefficient of capacitance. The ones made
with low K such as zero TC caps, are extremely stable. Some of
these caps fail, particularly the disc type, because the leads
have been stressed where they enter the body and have cracked it
allowing some air and moisture to enter. Disc caps can fail so
should never be left out of trouble shooting routine but neither
mica or ceramic need to be shot gunned as do paper or
electrolytic caps.

On 11/5/2019 12:10 AM, Craig Sawyers wrote:

Mica caps are a known weak point in the Racal RA17 receiver. They are

not a replace-on-sight because

there are lots of them, but worth bearing in mind that they can

occasionally be problematic.

Craig

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of

Ed

Breya via Groups.Io

Sent: 05 November 2019 00:04
To: [email protected]
Subject: Re: [TekScopes] 130 LC meter

Ceramic caps and even micas can get leaky after many years - not

often,

but I've seen it. Ed

--
Richard Knoppow
dickburk@...
WB6KBL

--
/Rajesh

--
/Rajesh

Hello Craig,

since you made your rude remarks to the fellow below who was asking about an active probe
the number of Tekscopes posts coming into my inbox have reduced. That is a fact.

Craig, your rudeness has stifled conversations. I do not like my enjoyment of this group being reduced.
I suggest that you apologise to the man for your rudeness, for your double standards and creating
a bad atmosphere.

I opened a post about an LCR meter only to find you talking about capacitors in a Racal RA17
receiver. You don't abide by your own rule.

Someone said this to me a while ago so I will pass it on to you.
" A lack of generosity in trivial matters is the Hallmark of an intellectual miser "
Think about it Craig,

I own a 7613 and have hankered after a 2465B so any stories about these instruments
are of interest to me. Thanks to you Craig, the stories have dried up.
Please Craig, no more Bullying Remarks to group members. I like to read what they have to say.

Regards,
John Crighton
Sydney