All, I just bought a very nice Tek oscilloscope cart for $40.00 that I plan on using with my Tek453 scope. The cart came with a 561B Tek scope and some plugins and I'm not sure what this scope was set up to do. The scope has two plugins, a Type 3A60 Amplifier and a Nelson Ross electronics Model 021 Spectrum analyzer. Attached to the cart is a type80 and type 81B plug -in which I think goes with a different scope.
Keith

The two big plug-ins mounted into the cart would likely have been intended for a (big) 580 series scope. Which is what the cart would have supported. I can't comment on the Nelson-Ross spectrum analyzer, but all together I'd say you got a nice package!

You seem to have a collection of odds and ends.

The 561B is a 10MHz scope, the Nelson-Ross spectrum analyzer needs the ramp signal from the Scope's timebase plug-in to operate.

The plug-in on the right is a 1MHz vertical amp.

The "Type B" is a 20Mhz vertical amp similar to the 53/54 and CA plug-ins for use in most 500 series scopes.

The Type 80 is a 85MHz vertical amp that uses a special cathode follower probe. This unit is for the 580 series scopes only, and not compatible with any other Tek scope series.

I don't see any horizontal "time base" plug-ins and unless you can find one, I doubt scope will be of much use.

Well, the cart was worth the $40.00 and the scope and odd N ends are in excellent condition so I may have to put the scope and plugins up on the classifieds.
Thanks,
Keith

The spectrum analyzer seems to be for the audio range (I see "kc" on the dial). If so, it's fun to play with but of no real use these days, since a computer sound card and FFT software will run rings around it.

(((((Well, the cart was worth the $40.00 )))))

I have 7 or 8 of those carts and they are nice,I use'm for tool carts in the barn,they are very well made with good caster wheels .nice find

I'd trade a timebase plugin for the Nelson Ross.

Mescalero, with a time base plugin will this scope be functional?
Keith

With baited breath: "Only if it works."

Let me do some homework. I'm pretty sure that I have one that will fit. The next question will be if the scope is functional. These were built to last. As well, they aren't so difficult to repair - most of the time.

What you need is something on the order of a 3B3. I have 21/22s. Those just won't fit.
Hopefully, somebody here has a 3B3 for you.

A computer sound card and available software may run rings around it as far as functions but I will bet that the plug in is better for analyzing low level signals that the sound card will never see.

Update: Keith graciously, most carefully packed and sent me the 561B with the audio band 20Khz type PSA-021 Nelson-Ross Spectrum analyzer and other Tek plug-ins. In exchange I offered to get it going and share findings with this forum. A walk through and photos follow. Enjoy!

561B Tektronix Scope

This is a nice scope. A mid 1960s design, 10Mhz rated with a high serial number of later manufacture. Perfectly suited for audio-band work. Compared to the 580s I’ve been working on this is a charm. Seems so compact, uncluttered and nice lines too!




SOP for older equipment means cleaning and spraying the switch controls in the mainframe and plug-ins with (DeOxit) before use. Turned out this unit was pretty clean with only a slight dust coating (not usual!). Decided not to variac or reform the mainframe caps for several reasons; including that it had recently been powered. When switched on both LV and HV power-supplies were found regulating and in tolerance. The calibrator had spot-on voltage for all ranges and needed no adjustment. It also provided a perfect 1khz square wave with great symmetry (oh how I wish the big 500’s had a calibrator frequency adjust!). A promising green dot appeared in view.

Tektronix Type 2A60 Amplifier

For the 561B in the spectrum analyzer configuration, the 2a60 sits in the right-hand slot and used as a sweep horizontal amplifier. It’s driven by a 1.8v sweep signal coming from the PSA-021 horizontal output via BNC connection. The first order of business was calibrating the sweep to fit the 10cm display and to start at the left-hand lower corner. Getting it to do this took quite a bit of fiddling and was very time-consuming. I suspect this will be required every session. For Tektronix, the type 2a60 is a minimalist single trace dc-1Mhz amplifier though is entirely suitable for this application.




Nelson-Ross PSA 021

For those unacquainted with a spectrum analyzer here's a little primer: it looks like an oscilloscope but instead reveals discrete frequencies that make up a composite signal. Specific frequencies are cast in relative strength (amplitude) along the Y -(vertical) axis. The different frequencies are shown spread across the frequency domain (instead of the time domain) on the X-(horizontal) axis.



Approaching this was at first daunting without a manual. While I had experience with a spectrum analyzer before, its been awhile and I was not entirely familiar with the NR control operation or nomenclature. However I was able to get response by fiddling around and using a HP 204c oscillator as a source. After awhile I figured out most controls. It has two basic spectral modes: Full scan (where the full 20khz spectrum is represented across the display) and Variable Dispersion (where the center frequency is selected and scan width is determined with the “dispersion” control). It offers two horizontal sweeping modes: Automatic (with horizontal sweep speed control) and Manual (operator turns the knob/ dot moves). These as well as the attenuator and IF amplifier controls all seem to work – though need calibration.

Initially I didn’t understand the purpose of the zero balance controls. Through internet research the manual for the Nelson Ross 001 and 011 predecessors was found . These have many of the same features and components but were made to fit the bigger 530/540 series scopes. Given this, I suspect the zero balance controls are equivalent to mixer controls described there and used to minimize the local oscillator bleed-thru seen on the display’s left hand side. I tried the suggested procedure though the results were not terribly impressive (and the documentation hints at this). Incidentally – unlike the 001 & 011, the 021 has its own sweep generator. The former used the 530/540’s sawtooth output as sweep driver – while the 561B, which is essentially an X-Y display, doesn’t offer.

Results

The photo below shows the spectrum using the scope’s 1khz calibrator square wave. The odd harmonics separated by 2khz are clearly visible. Bleeding from the local oscillator is somewhat rampant in the 2 left-hand divisions. As mentioned above this unit needs calibration and can be seen as compression across the spectrum. Fiddling, I suspect it is ranging across 23khz instead of 20khz – which is why the grid lines don’t line up. The Center Frequency and Dispersion controls also needs adjustment. At this point it would be extremely helpful get hold of a manual/ or some calibration instructions specific for the 021 which I’ve not as yet been able to find (assistance appreciated!).



Outtro

This PSA-021 was manufactured about 1970 though its design is contemporary with the Singer-Metric (panadapters) of the 1960s. I suspect units like these found home in medium and small businesses. It was probably displaced by the HP3580a when it debuted in 1973.

All-n-all this is a pretty neat setup and well represents the technology of it’s time. I have a bit more fiddling to do and things to check out – will be fun!


Thanks Keith!

And my very best regards!

Grid2

Good to see it working. You've probably seen this http://www.etestmanuals.com/Search.aspx?Mfg=NRS but if not you can buy a manual for $40.00.
Keith

Now we can finally, definitively answer the question:
Do the Mullard, Telefunken, or RCA 12AX7s sound best?