Author Topic: Test Equipment Anonymous (TEA) group therapy thread  (Read 2617765 times)

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Offline BravoV

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #50350 on: February 21, 2020, 06:36:31 am »
Any one have anything to say about Tektronix 2754 ?  :-//

Wiki -> http://w140.com/tekwiki/wiki/2754

As I rarely see discussion about it, even in this forum.
« Last Edit: February 21, 2020, 06:39:22 am by BravoV »
 

Online Cubdriver

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #50351 on: February 21, 2020, 07:17:55 am »
Any one have anything to say about Tektronix 2754 ?  :-//

Wiki -> http://w140.com/tekwiki/wiki/2754

As I rarely see discussion about it, even in this forum.

I rarely if ever see much of anything about Tek spec ans.  I suspect HP pretty much owned that market, at least in the US.  Seems Tek was scopes, and HP was pretty much everything else other than meters, where Fluke and Keithley were also part of the pack.

-Pat
If it jams, force it.  If it breaks, you needed a new one anyway...
 

Offline Zucca

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #50352 on: February 21, 2020, 07:38:59 am »
There’s one on eBay.de at the moment  :popcorn:

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F233498943571

Quote
Condition:For parts or not working
“Mal gehts - mal nicht”

 :-DD

https://www.ebay.de/str/chr

Here is Martin.M territory.

PS: I bet my ass bd has built a custom API to Ebay to be the first to get notified when something interesting pops up, regardless if co.uk .de or .com in USA.
« Last Edit: February 21, 2020, 07:41:46 am by Zucca »
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Online med6753

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #50353 on: February 21, 2020, 10:54:16 am »
For those who have been following the re-cap of the 535A power supply here is the schematic. In complexity it rivals many modern SMS supplies. The heart of the supply at the very bottom is the -150V reference. Without it nothing works. The 5651 VR tube and the 12AX7 provide the precise regulation. The three 12B4's are pass tubes to handle the load. The vacuum tube equivalent to a 78XX series regulator with pass transistors.

There are a grand total of a dozen aluminum electrolytics for this supply. 5 by the supply itself. 3 by the vertical circuit. 2 by the HV oscillator, and 2 behind the power transformer. 9 are complete. 1 left to do by the vertical circuit and 2 behind the power transformer. Going to work on that tomorrow. I also have to service the fan. It rattles a bit for a few minutes on initial power up then settles down. The bearings are most likely dry. 

Once all that is complete just check the cal and it should be done. 

An old gray beard with an attitude.
 
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Online Specmaster

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #50354 on: February 21, 2020, 11:11:51 am »
There’s one on eBay.de at the moment  :popcorn:

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F233498943571

Quote
Condition:For parts or not working
“Mal gehts - mal nicht”

 :-DD

https://www.ebay.de/str/chr

Here is Martin.M territory.

PS: I bet my ass bd has built a custom API to Ebay to be the first to get notified when something interesting pops up, regardless if co.uk .de or .com in USA.
Now what makes you think that I wonder  ::) 8)
Who let Murphy in?
 

Offline BravoV

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #50355 on: February 21, 2020, 11:15:56 am »
Any one have anything to say about Tektronix 2754 ?  :-//

Wiki -> http://w140.com/tekwiki/wiki/2754

As I rarely see discussion about it, even in this forum.

I rarely if ever see much of anything about Tek spec ans.  I suspect HP pretty much owned that market, at least in the US.  Seems Tek was scopes, and HP was pretty much everything else other than meters, where Fluke and Keithley were also part of the pack.

-Pat

Yeah, the rarely talk gadget like this creates hesitation in me, from the spec it self, its not a "mediocre" grade SA isn't it ? Cmiiw

Also the price offered here, powered on fine, to be honest, it is really tempting.  :palm:

Online bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #50356 on: February 21, 2020, 11:36:13 am »
There’s one on eBay.de at the moment  :popcorn:

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F233498943571

Quote
Condition:For parts or not working
“Mal gehts - mal nicht”

 :-DD

https://www.ebay.de/str/chr

Here is Martin.M territory.

PS: I bet my ass bd has built a custom API to Ebay to be the first to get notified when something interesting pops up, regardless if co.uk .de or .com in USA.
Now what makes you think that I wonder  ::) 8)

I did actually. It does gumtree and ebay. Although I don't use it now because it uses scraping so needs a lot of maintenance as they change the sites. This is only because I'm too cheap to hook into their APIs. Here's the scope of the thing. I'll list the gumtree provider here. Tabs are screwed for some reason - not sure why:



And a chunk of the ~80-ish rule definitons:



And the most IMPORTANT line of all:



This was all running nicely in AWS lambda but as mentioned I can't be arsed to maintain it now so I'm just using predefined ebay searches on iOS and checking occasionally.

This is how lazy us programmers are. Doing all that work to save less work  :-DD
« Last Edit: February 21, 2020, 11:38:27 am by bd139 »
 
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Offline beanflying

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #50357 on: February 21, 2020, 11:41:22 am »
It has four feet although the only you would maybe sit it on is another one or a Tank  :o More tomorrow as the Sun has set over the Volcano and I am beat  :phew:
Coffee, Food, R/C and electronics nerd in no particular order :)
 
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Offline Zucca

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #50358 on: February 21, 2020, 11:41:43 am »
bd playing on ebay reminds me super chuck norris bros

Can't know what you don't love. St. Augustine
Can't love what you don't know. Zucca
 
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Online Cerebus

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #50359 on: February 21, 2020, 11:52:22 am »
*currently brewing tomorrow's iced tea*

You can take the boy out of Texas/New York but you really can't take Texas/New York out of the boy can you? There he is in the Frozen Hell Hole of Hoth in winter and he's still drinking iced tea.
Anybody got a syringe I can use to squeeze the magic smoke back into this?
 
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Online bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #50360 on: February 21, 2020, 11:52:52 am »
For those who have been following the re-cap of the 535A power supply here is the schematic. In complexity it rivals many modern SMS supplies. The heart of the supply at the very bottom is the -150V reference. Without it nothing works. The 5651 VR tube and the 12AX7 provide the precise regulation. The three 12B4's are pass tubes to handle the load. The vacuum tube equivalent to a 78XX series regulator with pass transistors.

There are a grand total of a dozen aluminum electrolytics for this supply. 5 by the supply itself. 3 by the vertical circuit. 2 by the HV oscillator, and 2 behind the power transformer. 9 are complete. 1 left to do by the vertical circuit and 2 behind the power transformer. Going to work on that tomorrow. I also have to service the fan. It rattles a bit for a few minutes on initial power up then settles down. The bearings are most likely dry. 

Once all that is complete just check the cal and it should be done. 



Power supply is very similar to the 465 believe it or not. The only difference is the opamps here are 12AX7's and 6080's and the pass transistors are 12B4's and 6080's and there are more volts :-DD. Design is about the same!
 

Online med6753

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #50361 on: February 21, 2020, 11:58:06 am »
For those who have been following the re-cap of the 535A power supply here is the schematic. In complexity it rivals many modern SMS supplies. The heart of the supply at the very bottom is the -150V reference. Without it nothing works. The 5651 VR tube and the 12AX7 provide the precise regulation. The three 12B4's are pass tubes to handle the load. The vacuum tube equivalent to a 78XX series regulator with pass transistors.

There are a grand total of a dozen aluminum electrolytics for this supply. 5 by the supply itself. 3 by the vertical circuit. 2 by the HV oscillator, and 2 behind the power transformer. 9 are complete. 1 left to do by the vertical circuit and 2 behind the power transformer. Going to work on that tomorrow. I also have to service the fan. It rattles a bit for a few minutes on initial power up then settles down. The bearings are most likely dry. 

Once all that is complete just check the cal and it should be done. 



Power supply is very similar to the 465 believe it or not. The only difference is the opamps here are 12AX7's and 6080's and the pass transistors are 12B4's and 6080's and there are more volts :-DD. Design is about the same!

Yea, you're right. Concept is the same for both the 465 and 475.

Without looking the ref for the 465 is 55V and 475 is 50V....although I could have it backwards.
« Last Edit: February 21, 2020, 12:05:09 pm by med6753 »
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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #50362 on: February 21, 2020, 12:03:41 pm »
Yeah one or the other. I can never remember which is which. Usually the power supply is referenced to zero because tant  :-DD
 
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Online med6753

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #50363 on: February 21, 2020, 12:08:48 pm »
Yeah one or the other. I can never remember which is which. Usually the power supply is referenced to zero because tant  :-DD

I rotate the scopes around so I always have a pair on the "torture rack" to give them a run in while I'm working. Currently there's a 465B and a 475A happily cooking. Nary a smoking tant in sight.  :-DD
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Online med6753

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #50364 on: February 21, 2020, 12:14:08 pm »
It has four feet although the only you would maybe sit it on is another one or a Tank  :o More tomorrow as the Sun has set over the Volcano and I am beat  :phew:

Looks like you're home safe. Good deal! Get some sleep.  :-+
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Online med6753

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #50365 on: February 21, 2020, 12:19:08 pm »
bd playing on ebay reminds me super chuck norris bros



Is Chuck "shagging" the princess?? Nasty Chuck.  :P :-DD
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Offline Kilo Tango

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #50366 on: February 21, 2020, 12:31:45 pm »
Any one have anything to say about Tektronix 2754 ?  :-//

Wiki -> http://w140.com/tekwiki/wiki/2754

As I rarely see discussion about it, even in this forum.


I found this a couple years back, explains the range. On was on a Tek forum, sorry don't remember where exactly. The 494 appeared pretty good, and the 2784 very good.

********************************

As a guy who sold Tek Spectrum Analyzers as a career for 10 years (1980-90),
I can't let this go by unchallenged. When I started selling Tek spectrum
analyzers, Tek had discontinued the 1L and 3L series and also the 491. They
had just introduced the 492 a year or so before I started and Tek CLEARLY
had the advantage over HP for the portable (service) microwave market. It
wasn't until the introduction of the HP portable (can't remember the model
number) in the mid to late 80's that HP could touch Tek in that market. I
will admit that in the lab and production line environment, HP definitely
had the advantage. Also, HP had more to offer in the audio spectrum
analyzer world. As Tek upgraded the 492 to the 494, 495, 492BP, and 494A,
HP finally got the picture and brought out a decent portable that was
definitely competitive with the 490 series. Then Tek brought out the 2710
which had MUCH more to offer than the HP 8590 and was priced in the same
range (low, about $10K). The 2710 was just about the best "bang for the
buck" that I have EVER seen in a spectrum analyzer. I sold a LOT of them,
one at a time, since my territory (Pacific Northwest) did not have multiple
spectrum analyzer users. I have a 2710 in my collection. Tek's last real
effort in the analog spectrum analyzer world was the 2782 and the
improvements that followed it (2784, etc.). I left Tek just about the time
the 2782 was introduced so I did not get to sell many of those (one or two
to Boeing, as I recall it . . . ) The 2782 was really an engineering
marvel, in my opinion. It virtually had the performance of the very best
lab analyzers but in a portable package. I really wish I owned one . . .
Unfortunately, it never seemed to me that Tek was really behind supporting
the 2782 (and 2784, etc) like they had the 490 series. I never saw a
completed service manual for the 2782, for example, although I have heard
rumors that one exists. It was then, that Tek decided to dismantle what I
thought was one of the finest (arguably, maybe the VERY finest) spectrum
analyzer engineering groups and give up that market to HP. I was very sorry
to watch that happen and I always thought it was a terrible mistake on Tek's
part (I still do). After the 2784, what could that engineering team have
done next? We will never know . . .


Stan can probably weigh in on this with lots of good detail, but
basically, the Tek 492 was introduced in 1980. It covers to 21 GHz in
coax and to 220 GHz with external mixers. The option 6 was added as a
way to order the machine at a lower price without the microwave bands
for the many applications such as broadcast and two-way that don't
need that coverage.

Those must have sold well enough to justify a stand-alone model
designation - 496, so a 492 option 6 machine would be the same as a
496, just a little earlier production.

Then in the 1984 time frame, Tek introduced the 494 which added many
features to the platform including synthesized [no drift] operation,
highly accurate and stable timebase, frequency counter capability, non-
volatile storage of trace and setup information, direct button entry
of most parameters including center frequency, RBW, etc.

Later the 494A added a few more features such as marker capability.
The 495 is a derivative of that machine without the microwave bands.
With the P option the 494 and 495 can also directly control a plotter
for hard copy output.

Ultimately, other models such as the 492A, 492B, 497, were introduced
with various combinations of firmware based features, frequency
coverage, time base accuracy, etc. to fill in the model range at
different price points. Then they added the 275X lab machines and
later the outstanding 278X color machines.

That gave Tek a huge portfolio of analyzers - something for just about
everyone with prices from the 2710 at $8750.00 to the 2782 at
$69,000.00 [in 1991]

How sad to see them discontinued.

A 494AP or 495P is still an terrific machine [as is a 496 if you don't
need the bells and whistles]

RE: [TekScopes] 2755AP service/ops manual needed

I'm not sure exactly what features a 2755 has, but at the end of the day
it's just a rack-mount version of the 492, 492A, 492B, 494, 494A, 495, or
496. You can use the manuals for the 490-series equivalent with no problem
at all.

If it goes to 21 GHz and includes markers and a built-in counter, it's a
494AP.
If it goes to 21 GHz and includes a counter but no markers, it's a 494P.
If it goes to 21 GHz and includes markers but no counter, it's a 492A.
If it goes to 21 GHz and doesn't include either of those features, it's a
492.
If it goes to 1.8 GHz and includes markers and a built-in counter, it's a
495P.
If it goes to 1.8 GHz and doesn't have either of those features, it's a 496.



One of my earliest encounters with the very kind Stan Griffiths was this fantastic response he wrote to a question I had about the Tek 492 series spectrum analyzers. I'm sure others will find this useful (forgive my poor formatting. If this doesn't come out right, I can fix it later and repost it).

"Well, now, I started at Tek in 1960 with a little time out from 1967-1970. From 1979-1989, I sold spectrum analyzers in the states of OR, WA, ID, MT, and AK so I know the history of the 49X products pretty well. It all started in about 1978 with the introduction of the 492/492P. This was a break-through in several areas over the 491. First, it was actually CALIBRATED with regard to signal levels and flatness of frequency response instead of just relative values like the 491. Second, since it used a YIG oscillator (state of the art at the time), the first IF frequency was about 2 GHz which meant there were no spurs in band one (up to 1.8 Ghz). This was another HUGE improvement over the 491. The frequency accuracy was improved over the 491 also, from about 10 MHz to about 5 MHz, but this was to become even much better in the future. Also, I believe the 491 was good up to about 40 GHz with external waveguide mixers, but the 492 was good up to 220 GHz with external waveguide mixers. The 492 appeared in the 1982 Tek catalog at $21,300. The 492P (GPIB Programmable) appeared in the same catalog for $27,500.

There were a couple of significant options you could get for the 492/P:

Option 01 Internal Preselection. Add $3900. This option greatly reduced spurious responses in the bands from 1.8 GHz to 21 GHz.

Option 02 Digital Storage. Add $1900. This option really made for a nice display and allows for sweeping very slowly without the trace fading away like it does with a P7 phosphor (ala 491).

Option 03 Phase Lock Stability and 100 Hz resolution. Add $3500. The normal 492 had only 1 KHz resolution since the local oscillator was not stable enough to support better resolution than that. With this option, you could actually make decent measurements using the 100 Hz resolution bandwidth filter all the way into the millimeter microwave bands.

The external waveguide mixers came in a set of 5. You could get them individually or in various combinations. A full set was $8260.

Option 08 actually DELETED the external waveguide mixer capability and reduced the price by $1750.

The whole point here is that if you are considering buying a used 492/P, what options is contains makes a HUGE difference in its performance . . .

Also appearing the 1982 Catalog was the brand-new 496/496P. The 496 was $22,950 and the 496P was $26,950. It was basically a "band one only" 492 with digital storage and phase lock as standard features and improved resolution bandwidth to 30 Hz, compared to 100 Hz in the 492. Since it stopped at 1.8 GHz, the preselector and external waveguide mixer capabilities did not apply to the 496.

Also, appearing about this time was an odd-ball called the "492-6". This was really a 496 built for the military before the 496 was announced to the public. This instrument was never in the Tek catalog so there really is not
much known about them by the average buyer. These are becoming available on the surplus market now and I am sure some people are fooled into thinking they have the frequency coverage of a real 492, which, of course, they don't.

You have to remember that these prices went up every year, and usually by a substantial amount.

The next major change was introduced in 1985 in the form of the 494/494P. The 494 was essentially a fully loaded 492 (with external waveguide mixer capability now up to 325 GHz), but now having super-accurate frequency
measuring capability. It had counter accuracy up to 325 GHz, if you had the waveguide mixers to get you to that frequency. Center frequency was known to within 10 Hz or so in the 494. The price went up too. $46,400 for a 494P. I LOVED that instrument. Lab quality spectrum analyzer measurements in a portable instrument. Beat the Hell out of anything HP had that pretended to be portable at the time. You could also store up to 9 (I think) waveforms in non-volatile storage. Another neat feature was a "HELP" button. Can't remember what one of the buttons or knobs is for on a 494? Just hit the "HELP" button and then push the button in question or rotate to knob you don't understand. An explanation of that control suddenly appears on the screen. You could get it in English, Spanish, German, or French.

Next, came the 495/495P in 1987 which was essentially an improved 496. The 495P was priced at $29,950. It had all the features of the 496, including stopping at 1.8 GHz. Frequency accuracy was like the 494. "Markers" were
added to aid in making some measurements. The 496 was discontinued.

At this same time, the 492/492P became the 492A/492AP. It had counter frequency accuracy and markers as well. Digital storage was standard as was phase lock stability. The tracking preselector was optional. It did not have the "help" mode. The 492 and 492P were discontinued.

Also, at this same time, the 2754/2754P and 2755/2755P made their appearance. These were nothing more than a stripped down 492A or a 492A/P in a slightly different external package. They weren't very popular because they didn't really bring any new measurement capability to the table.

In 1988, the 494/P was upgraded to the 494A/494AP and contained virtually all of the features discussed above. The price for a 494AP was now up to $47,995.
The 2756/P was also introduced and was nothing more than a 494A/494AP in a different exterior box. The 2753/P also appeared in 1988 and was nothing more than a 495/P in a different box.

The 2710 was also introduced in 1988 but that is another whole story by itself.

In 1989, the 492A/P turned into the 492B/P and I don't recall anything specific about that. The 49X line had matured.

Late in 1989, the 2782 was introduced at just under $70,000. I sold a couple of those and then left Tek for another company.

Also, there was the TR503 tracking generator that sometimes went as an accessory with all the various 49X spectrum analyzers. It worked on band one (100 KHz to 1.8 GHz) only. It sold for about $7,000 including a TM503 to power it.

Personally, I have a 2710, fully loaded with tracking generator, digital storage, counter, etc which is my workhorse. I also have a 491 in mycollection just for historic purposes. I also have some 1L and 3L spectrum analyzers, most of which don't work, and I have no idea how to fix them."
----- Original Message -----

***********************************************************

I remember when some bunch broke up a 2784 that had a duff ( or missing ? ) PSU and sold off the bits. I tried to buy it whole, but they wanted >£1000  :'( :'( :'(

Ken
 
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Offline BravoV

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #50367 on: February 21, 2020, 12:42:57 pm »
Ken , wow ...  :o , thank you Sir.  :clap:

Now time to read and digest all those meodels.  :P

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #50368 on: February 21, 2020, 12:43:56 pm »
Power supply is very similar to the 465 believe it or not. The only difference is the opamps here are 12AX7's and 6080's and the pass transistors are 12B4's and 6080's and there are more volts :-DD. Design is about the same!

I quite like the simplicity of that, and you know what? It works with valves in dresses (trannies) too:

935840-0

(Anybody naïve please note: this almost certainly won't work as given as I've given no thought to AC stability, although it might make a passable oscillator.)
Anybody got a syringe I can use to squeeze the magic smoke back into this?
 
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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #50369 on: February 21, 2020, 12:56:39 pm »
I've built a few power supplies like that. They work very well. But yes unless you get the feedback compensation right they turn into wild oscillators. Lazy way is to add some miller capacitance to the transistors in the long tail pair. I managed to get away with reducing this to one capacitor if you don't put a massive inductive load on the output  :-DD

I can't find the actual board (its in a box somewhere) but I made a dual rail one as well which worked pretty nicely. The JYK headers were substituted with trimmers for "static" usage.



The long tail transistors in the actual built version were to be heatshrinked together as well. I also designed a tracking version but never put it together.
« Last Edit: February 21, 2020, 12:59:04 pm by bd139 »
 

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #50370 on: February 21, 2020, 01:11:09 pm »
I take back what I said. Here's a loop gain plot for the circuit above (resistive loading only). Stays completely happy with 100 uF on the output too. But yes, stick some inductance on there and it'll probably go stratospheric.

Edited to add: I bet that would all change if I substituted realistic devices rather than just 2N3904s throughout.

935864-0
« Last Edit: February 21, 2020, 01:16:30 pm by Cerebus »
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Online bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #50371 on: February 21, 2020, 01:18:13 pm »
Set them all to 2n3055's  :-DD :popcorn:

Edit: I still really like the HP 6236B design. Almost the same as the Harrison design 30 years before. Almost the same as the Keysight version 30 years after. Thats when you know you got shit right! Also not a whole lot of loop compensation going on so it makes sense:

« Last Edit: February 21, 2020, 01:28:48 pm by bd139 »
 
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Offline Zucca

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #50372 on: February 21, 2020, 01:35:53 pm »
Forgive me father, I still have impure thoughts

Can't know what you don't love. St. Augustine
Can't love what you don't know. Zucca
 
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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #50373 on: February 21, 2020, 02:03:33 pm »
Set them all to 2n3055's  :-DD :popcorn:

Edit: I still really like the HP 6236B design. Almost the same as the Harrison design 30 years before. Almost the same as the Keysight version 30 years after. Thats when you know you got shit right! Also not a whole lot of loop compensation going on so it makes sense:



What I do not understand: why using a PNP power transistor as the series regulator (Q1). What is the advantage? I've learnt years back, that the PNP transistors are not so good spec-wise as the NPN ones. Same is said about the LM78XX vs. LM79XX. Lots of people dislike the 79XX because of their tendency to oscillate.

 :-//
“Chaos is found in greatest abundance wherever order is being sought. It always defeats order, because it is better organized.”            - Terry Pratchett -
 

Online Cerebus

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #50374 on: February 21, 2020, 02:04:12 pm »
Forgive me father, I still have impure thoughts



That reminds me, I have an AvE episode in the queue to watch. "Keep your dick in a vice"
Anybody got a syringe I can use to squeeze the magic smoke back into this?
 
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