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Re: Spectrum analyzer Tektronix 7L13 on mainframe Tektronix 7603

Attilio
 

Nenand,
thanks for the information.
At the moment I was able to recover a 7613 mainframe, I was satisfied.
Can you give an indication as to which source noise should I buy ?
What can I do to reduce the possibility of damage the first 7L13 mixer using an active probe?

Thanks a lot and greetings to all


Re: Tek 453A

Dale H. Cook
 

On 12/27/2020 12:18 AM, Bob Albert wrote:



It's repairable. But it could have serious problems and if you don't
know, pass on it.



I agree with Bob. Also bear in mind that for many oscilloscope repairs you need a working oscilloscope to troubleshoot the dead 'scope.
--
Dale H. Cook, GR/HP/Tek Collector, Roanoke/Lynchburg, VA
https://plymouthcolony.net/starcity/radios/


Re: Spectrum analyzer Tektronix 7L13 on mainframe Tektronix 7603

Attilio
 

tinkera123 which diodes did you use to protect your SA?
Thanks, bye
Attilio


Re: Rescuing 500s from tube snatchers/scavengers - how much is it worth

snapdiode
 

Do you know where to get a set of new Bendix 6900's?


Re: Tek 453A

Bob Albert
 

It's repairable.  But it could have serious problems and if you don't know, pass on it.  They are pretty old; I have one and it's great but only 50 MHz or so.  I no longer use mine due to getting higher performance units.
If it doesn't work, forget it.
Bob

On Saturday, December 26, 2020, 08:57:58 PM PST, Maurice Smulders <maurice.smulders@gmail.com> wrote:

I can obtain a Tek 453A locally, but it doesn't show a trace, so I have no idea yet what is broken. What would be a good offer for it, and is it usually repairable?

- Maurice


Tek 453A

Maurice Smulders
 

I can obtain a Tek 453A locally, but it doesn't show a trace, so I have no idea yet what is broken. What would be a good offer for it, and is it usually repairable?

- Maurice


Re: PG506 calibrator generator voltage error

Eric
 

Simon,
The calibrated output and the high amplitude output (same BNC) are cal in to 1Meg Ohm. The fast rise are cal in to 50 Ohms. Have you checked the calibration on the PG 506? If I recall correctly it is done at DC. There is a switch inside the calibrator to stop the squairwave so you can calibrate it with a DMM. If you do that you may need to match the 1Meg input of the DMM there was a way to do that in the service manual. Also if I remember correctly from when I calibrated mine there was some things about the contacts in the relays being a soar spot on these but I could be mistaken on that.

Eric

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Rick
Sent: Saturday, December 26, 2020 7:43 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] PG506 calibrator generator voltage error

Simon, the PG506's require a 50 ohm termination on the scope. Without it the voltages will be erroneously high. On mine it even adds a lot of distortion to the pulse. Do you have a 50 ohm terminator on the line?

Rick


Re: PG506 calibrator generator voltage error

Gif Sim
 

thanks rick for your interest ..... I'm going to sleep ... it's 3:00 am .... maybe tomorrow I'll do other tests and measurements and I can tell you more ..... bye


Re: PG506 calibrator generator voltage error

Gif Sim
 

hi rick
50 ohm termination is used in fast rise outputs
I don't use fast rise outputs
I connect to the standard amplitude output which supports 50 ohm and 1Mohm
if you look at the amplitude standard output female bnc you will see that the ground is isolated from the pg506a frame with a white plastic insulator
The amplitude standard output has a floating power supply to ground
I connect the oscilloscope input (which is powered at 220v mains voltage) to the standard voltage output of the pg506a....
the mass of the oscilloscope bnc is connected to the network ground
when I connect it to the output of the pg506a the central variable out potentiometer no longer has any effect .... the display shows a fixed number and the output voltage is wrong it is higher ....... if I connect a standard output to a battery powered multimeter or oscilloscope everything works and the voltages on the output bnc are right ... if I turn the central potentiometer the voltage varies and the display works perfectly (indicating the% of error) .........
something happens inside the pg506a !!!
but I can't understand what!
with the service manual I checked the power supplies and some diodes, zener, transistors, connections ....... everything seems okk ....

I do not know what to think !!! I'd start crying .. hey


7904 scope

Bill Riches
 

I am looking for a working 7904 scope less plugins.  I have a bunch of good ones.  I gave up on mine that went bad this summer.
73,
Bill, WA2DVUCape May, NJ609 425 8651


Re: PG506 calibrator generator voltage error

Rick
 

Simon, the PG506's require a 50 ohm termination on the scope. Without it the voltages will be erroneously high. On mine it even adds a lot of distortion to the pulse. Do you have a 50 ohm terminator on the line?

Rick


Re: Rescuing 500s from tube snatchers/scavengers - how much is it worth

John Williams
 

Hi. There is no shortage of NOS tubes in my experience. For example, Radio Electric Supply (https://vacuumtubes.net/ ) in Florida has over 12 million tubes in their stock. I ran across a guy recently at a hamfest who has 7 tractor-trailers on his property stuffed to the top with new tubes. I think there is a common belief that the tubes in Tektronix equipment are somehow better than new one you can buy from a dealer. Nothing could be further from the truth. Most have hundreds of hours on them and a lot of stress. Plus nobody is going to guarantee anything about them, or even test them. Just my 2 cents worth.


Re: Spectrum analyzer Tektronix 7L13 on mainframe Tektronix 7603

Nenad Filipovic
 

On Sat, Dec 26, 2020 at 10:42 AM, Attilio wrote:
I may have found a 7613 mainframe that has STORE mode.
Using 7L* SAs in 7854 is a song. It's not just the digital storage, it's the averaging that can significantly help smooth the measurement and increase your SNR. I do it all the time with my 7L5 and also 7L13. Getting a 7854 would really help.

I am looking on the internet for a TR502 (Tracking Generator) with its power supply.
TR502 is great, but you can also do much with a noise source which you can get cheaply on eBay. Most will cover the full frequency range of the 7L13.

what accessories should I buy to use with my SA ?
Certainly not among the first things you should try with your SA, but I can't skip mentioning it - the P6201 or a similar active probe. It would replace the low 50ohm input impedance of your SA with a high impedance low capacitance load. It can greatly help debug/calibrate the high impedance RF circuits (receiver IFs, mixers...). Note that using an active probe with your SA kind of quadruples the danger of killing your mixer with accidental DC, so the utmost care is necessary.

Best regards and Happy Holidays,
Nenad FIlipovic


Tektronix P7001/ 7704A available free in SE NH

JOE
 

Hi,

I have a P7001 / 7704A free for the taking. It's located in SE New Hampshire. Pickup only. Too big to ship.

It's not working. I believe the problem is in the digital unit power supply.

No plugins are included.

I believe it to be complete. It was working when I put it in storage. Has core memory.

Email me for photos.

Joe


Rescuing 500s from tube snatchers/scavengers - how much is it worth

Nenad Filipovic
 

Hi Everybody,

Inspired by recent talk of the admirable 500 series, I'd like to share my story and some questions that keep bugging me. I'm in Eastern Europe.

A month ago a local trader in scavenged EE components (whom I know for some time) boasted of his new catch - a complete 545A. He had already sold half of its 6DJ8s, and was getting ready to take it apart for sockets and other stuff. To cut the story short I held him off, went to see it in person (excellent condition, no corrosion, just dusty), and redeemed it with as much of the original tube set as I could (read: no 12AX7s/12AT7s and just a few spent 6DJ8s). Total cost (part cash part some of my stuff traded): approx $300. Fortunately I had a graveyard of 6DJ8 (randomly accumulated pile with ~50% life in them) to stuff the 545A and it came to life. So it wasn't even broken, I was able to calibrate it with half dead tubes. CRT is sharp and like Vegas at night. Two years ago I did the same with a 555 (somewhat poorer condition and missing power supply) for approx. $350. I cannot even fire it up, it's sitting in my storage hoping for that power supply to show up one day. For comparison I paid $400 for my 7104 with 1x7A29, 7B10 and 7B15.

What I cannot grasp are the market facts (value in $) behind this. In France (far richer and more developed economy than Eastern Europe) complete 500s do come up on eBay for $100-$250. Yet somewhere else where a teacher's salary is like $450, there seem to be people willing to dish out $40 for 1 used Buggle Boy (Amperex Holland) 6DJ8, $60 for Siemens or $80 for a Telefunken. Or are they? With this math someone may profit hundreds of $ for a 585 dug up out of some old man's basement. I understand the fact that there are less and less NOS tubes and it pushes the price up, but still the buyer's motivation will put the final cap on it. So I'm wondering who exactly are the people ultimately driving the scavenging of 500s? Are the snatchers in poorer countries just selling on eBay to the richer? There are hundreds of "buy it now" overpriced ads on eBay sitting there for years, does that mean there is a huge stock of 500s guts hopelessly stuck in some collective pipe dream? All I know is I better not share the cost of my two acquisitions with my better half.

Best regards and Happy holidays,
Nenad Filipovic


Re: Spectrum analyzer Tektronix 7L13 on mainframe Tektronix 7603

tinkera123
 

Just as I always try to remember to set my Scope coupling to Grd and Vertical amp to min sensitivity ... I do the same with SA ie max Attenuation at 'turn-off'.
Also, I have built my own DC block with BNC connectors, and diodes to take out voltage spikes (circuit suggestions are on web) ... again, not foolproof.
Cheers, Ian

--
Cheers,
Ian,
Melbourne, Australia


Re: 2465B calibration temp?

 

On Sat, Dec 26, 2020 at 09:13 PM, Jean-Paul wrote:


To précise the questions:

IF the scope was already full CALed but the V or H is still off 1-3 % (perhaps
bad first attempt at CAL?) can the V/H CAL be done with case closed or it must
be open to reach trimmers?
Hi Jean-Paul,
You mean that the 'scope has been adjusted some (long) time ago and now hor. and vert. deviation are off? If not, and the 'scope is "still off", as you write, after cal, something has gone wrong.

Is it that you'd rather not remove the case? Then you have to realize that you can't call up the Cal routines without having the cal/nocal jumper in the "cal" position. If it isn't (like it should), you'll have to open the case anyway.

The SM tells you that you need to select a Cal menu choice and adjust a few pots, as a starting situation, after which the individual settings are done in menus, without touching the pots.
By observing the starting positions, you can determine whether you have to adjust the pots. I wouldn't advise attempting to do the cal. with the initial setting off.

Look it up in the SM. It's all in there and described very clearly.

Raymond


465 Scope AC Gnd DC Coupling Switch

JJ
 

Gentlemen,
My 465 has a stuck coupling switch - it developed during a project that I
am working on. It's stuck in the AC position. I don't want to force it. I
haven't taken the unit apart yet but with a Hail Mary Pass I sprayed a
little DeoxIT through the front slot. No glory! I checked through the
message archives but didn't find anything.
Before I open it up and break something, I was wondering if anyone else has
had the problem and whether the switch is repairable. I didn't see any
switches for sale on eBay.
I'm now using my 7904 so I'm not pressed to get the 465 functional.
Merry Christmas and Happy New Year to everyone.
Best,
John Justin


Looking for some TM500 modules

Paul Amaranth
 

I'm looking for a few TM500 modules

SC504 or 503 scope
A multimeter module (DM501,502, etc)
PS503 power supply (2, actually)

Working would be nice, but not necessary. I'd be happy
to take broken modules off your hands if they're cheap.

I picked up a TM506 the other month (for $5) and it seems
that it would make my desk a little neater if I could
populate it with some common instruments.

Drop me a note OFFLINE. If you're reading this as email,
my address will be in the sig, if through the web use
the groups.io messaging service, I think I have that
set up right.

thanks
Paul

--
Paul Amaranth, GCIH | Manchester MI, USA
Aurora Group of Michigan, LLC | Security, Systems & Software
paul@AuroraGrp.Com | Unix/Linux - We don't do windows


Re: 2465B calibration temp?

Jean-Paul
 

Raymond and Victor,

Many thanks! I have done full cals on these but some years ago. Am Aware of cooling of A1 PCB, U800 etc with case open.

I have TEK manuals printed originals, PG506 and TM501, attens, terms etc.

To précise the questions:

IF the scope was already full CALed but the V or H is still off 1-3 % (perhaps bad first attempt at CAL?) can the V/H CAL be done with case closed or it must be open to reach trimmers?

Best Wishes,

Jon

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