Date   

Re: Sloppy front panel BNC connector - 475

SCMenasian
 

The excess (over thermal) noise due to a resistor is proportional to current (and, in some cases, possibly even a power of current). If there is no DC current flowing (as is, I think, your case), only AC current would contribute. A large AC current implies a large signal; so, the S/N ratio, even for a carbon composition resistor, would be large and the excess noise of a carbon comp resistor over a metal resistor would probably be insignificant. The current path in metal film resistors is often a spiral cut in the film, at least for high resistance values; inductance could be a problem at high frequencies - I don't know about 50 ohm resistors, though.


Re: 2235 Horizontal Calibration Issue

Stephen
 

On Wed, Jan 27, 2021 at 08:58 PM, Ozan wrote:


After changing the zener let us know new voltages at the critical pins
(earlier list).

Ozan
Back in business.
Changing that WR749 brought the scope back to life.
I’ll take the new measurements soon.
All I can say at this point is the it still has the same non linear issue.


Re: What are the differences between the P6302 and A6302 current probes?

Stephen
 

A bit off topic, sorry, but is the P6303 even worth getting at all?


Re: Tek 576 possible power supply failure

Michael W. Lynch
 

Martin,

Well, at least you can mark those off the list of possible causes. I had a couple of bad bulk filter caps in the power supply that loaded down the supply as well. The 5V supply is especially vulnerable to this. I also found several shorted electrolytic caps scattered around that added load as well. Perhaps you could measure the load on each individual supply at the LV power supply and determine which one is drawing excess current? I had to go back and isolate each supply individually to finally locate the source of the excess load.

--
Michael Lynch
Dardanelle, AR


Re: NEW TOPIC: Outstanding Rockland Instruments 7000 Plugin; WAS: Slightly OT- Wavetek 7530B?

nonIonizing EMF
 

Hi Dennis,

Do you mind if I copy and paste the above into the Tekwiki's for both?

Seems like good info to have documented while on the topic and available.

I know with the PMI systems... seems all the info in long gone and forgotten other than what I've been able to find with what manuals I've been able to acquire.

Thanks Dennis.


NEW TOPIC: Outstanding Rockland Instruments 7000 Plugin; WAS: Slightly OT- Wavetek 7530B?

 

Hi Dana,
The Rockland Instruments 7530A and 7530B Spectrum Analyzer plugins for Tek 7000 scopes are outstanding, and unique, Spectrum Analyzers.

In the mid-1970s Rockland Instruments was a small company driven by brilliant engineers who thought outside the box to create state of the art instruments. It was no surprise that Wavetek, which had greater resources and name recognition, bought them several years later to get access to their engineering team.

In 1976 they were among the first, if not the first, to create a spectrum analyzer using an A/D to sample the incoming waveform, convert it into a stream of digital values, perform an FFT (Fast Fourier Transform algorithm) on the data, then use a D/A to convert the results back into the display that appears on the CRT of the 7000 series scope.

HP was not far behind Rockland Instruments. By comparison Tektronix was so deeply committed to swept-IF Spectrum Analyzers that it took over a decade before they realized the advantages of FFT Spectrum Analyzers.

The only limitation the 7530 has is due to the speed and performance of microprocessor chips available in the mid-1970s. The only solution at the time that would be fast enough and precise enough was to create a 12-bit wide CPU using bit-slice microprocessor chips.

The result is a 3-wide 1HZ to 100KHz FFT Spectrum Analyzer plugin for the 7000 series scopes that meets or exceeds the specs of the 7L5 in the same frequency range.

Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of danadak
Sent: Friday, January 29, 2021 8:21 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Slightly OT- Wavetek 7530B?

I just posted schematics, user manual here (7530A) - https://groups.io/g/TekScopes/files/Rockland%20Wavetek%207530A%20FFT%20Plugin

Regards, Dana.







--
Dennis Tillman W7pF
TekScopes Moderator


Re: 3 files uploaded #file-notice

nonIonizing EMF
 

Thinking these are best to go into the respective Tekwiki regarding:
https://w140.com/tekwiki/wiki/Rockland_7530A
https://w140.com/tekwiki/wiki/Rockland_7530B

I can go ahead and add. If you have anymore, I can add those also.

On Fri, Jan 29, 2021 at 08:20 AM, "TekScopes@groups.io Notification" <noreply@groups.io> wrote:


The following files have been uploaded to the Files area of the
TekScopes@groups.io group.

* /Rockland Wavetek 7530A FFT
Plugin/Rockland_7530A_FFT_Spectrum_Analyzer_Operating_Manual_1980.pdf (
https://groups.io/g/TekScopes/files/Rockland Wavetek 7530A FFT
Plugin/Rockland_7530A_FFT_Spectrum_Analyzer_Operating_Manual_1980.pdf )
* /Rockland Wavetek 7530A FFT Plugin/Rockland_7530A_Schematics.pdf (
https://groups.io/g/TekScopes/files/Rockland Wavetek 7530A FFT
Plugin/Rockland_7530A_Schematics.pdf )
* /Rockland Wavetek 7530A FFT Plugin/TekScopes@groups.io _ Rockland 7530B
Spectrum Analyzer plugin.pdf ( https://groups.io/g/TekScopes/files/Rockland
Wavetek 7530A FFT Plugin/TekScopes@groups.io _ Rockland 7530B Spectrum
Analyzer plugin.pdf )


Re: Tek 576 possible power supply failure

 

Michael,

this time it does not seem to come from the HV section. I disconnected step generator and HV, no change.

I'll disconnect the plus and minus 12,5 supplies as they can tear down the 75V suppy when shorted.
And the 75V supply as it can tear down the 12,5 supplies.
-> Thats what the service manual says. Headscratching.

cheers
Martin


Re: Sloppy front panel BNC connector - 475

Torch
 

Lacking a 43 ohm resistor in my current stash, I soldered two 22 ohm resistors in series temporarily to verify there is no issue with the BNC ground side. That part is OK, no loss of signal when I wiggle the connector, but there is definitely more ringing looking at a fast pulse. I suspect this is due to the additional inductance caused by stringing two resistors together. Would not the additional length of adding a stranded wire cause a similar artifact?


Re: Model 7530 Spectrum Analyzer plugin made by Rockland Scientific Corp for Tek 7000 Series scopes

danadak
 

I just uploaded schematics, user manual here - https://groups.io/g/TekScopes/files/Rockland%20Wavetek%207530A%20FFT%20Plugin


Regards, Dana.


Re: Slightly OT- Wavetek 7530B?

danadak
 

I just posted schematics, user manual here (7530A) - https://groups.io/g/TekScopes/files/Rockland%20Wavetek%207530A%20FFT%20Plugin

Regards, Dana.


3 files uploaded #file-notice

TekScopes@groups.io Notification <noreply@...>
 


Re: Sloppy front panel BNC connector - 475

Roy Thistle
 

On Fri, Jan 29, 2021 at 07:01 AM, Torch wrote:


carbon composite resistors are noisy. Does that also apply to electrical noise
in the scope front end?
It's like 53 ohms... At 1 Hz bandwidth, and room temperature, that's about 1 nV. (possible more about carbcomp, in a later post)


Re: What are the differences between the P6302 and A6302 current probes?

Jean-Paul
 

Atillo: I have had many of these probes and the other similar.

On ebay BEWARE as it is VERY easy for a probe to be dropped even 5 cm and break the thin ferrite core.

The damage can be invisible but the pulse and response will be bad, and impossible to fix.

Suggest to bid ONLY buy if they are guaranteed new or use 100% working with chance to return.

I have paid $35..65 but perhaps in 1990s..2000s

If ANY physical damages in photos, avoid.

fai attenzione al compratore

Ciao!

Jon


Re: [Tek 485] No intensity control

 

Jose,

from the schematic for the CRT circuit <13> it looks like you could measure the value of R1603-R1609 by either lifting only one leg of either R1603 or R1604, or by lifting one leg of both R1605/R1606 and R1608/R1609. If you could easily disconnect the DD connections then there would be no need to lift any legs of any resistors.

-- Jeff Dutky


Re: What are the differences between the P6302 and A6302 current probes?

Attilio
 

Thank you very much David for the information.

-- Cheers
Attilio


FS: Tektronix 492 to 492P Spectrum Analyzer mod kit 040-1038-03 plus manuals

Ken Eckert
 

Deane Kidd put this mod kit together for me years ago. It was an official Tek kit p/n 040-1038-03. Auction also includes all the original 492/492P manuals: OP, Service Vol 1, Service Vol 2 and Programming along with the mod sheets/documentation. Photos on request.

This kit includes everything (Deane was meticulous) including all the cables, screws and cable clamps.

I never installed it, I sold the 492 a while back.

Asking USD$250 or best offer


Re: What are the differences between the P6302 and A6302 current probes?

 

AFAIK, A6302 and P6302 are the same thing.

David


Re: Tek 567 trace wandering

Michael W. Lynch
 

On Fri, Jan 29, 2021 at 04:33 AM, <keith@peardrop.co.uk> wrote:


The second issue is the looping compensation seems very stiff, and turning it
has no visible effect at all. Is it likely to have seized, and how does one
get at it - again it doesn't look easy to access.
That looping compensation control is usually stuck where the shaft passes through the chassis on the capacitor itself. You can access this a little better by removing the bottom panel, still a pain, but does give more room to work and better access. I used a bit of penetrating oil on mine and finally got it freed up.

--
Michael Lynch
Dardanelle, AR


Re: Tek 576 possible power supply failure

Michael W. Lynch
 

Martin,

Did you disconnect the 100V to the HV section? Sounds like another shorted HV transformer.

--
Michael Lynch
Dardanelle, AR

7581 - 7600 of 184731