distortion analyzer recomendations?

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#301
I appreciate the feedback. I was looking for 2465B before when I fell for the pitch on TDS360; we'll see, I made end disliking digitals like most. I'll never part with the 5440; its my father's old scope; even have a new tube in reserves and a 2nd 5440 for parts.. I'm curious how one would go about adding more than the 3 pulg-ins; best swap-out for 5a22n would be to pull one of (2) 5a48 dual trace amps out: because I took your advice and quickly found/bought a 5a22n for $55.
The only avoidable VNA ( assume you mean vector network anal) I've read of is Paul Kiciak's, N2PK. Any others? I not real familiar it; but will be soon. It's my understanding any PC based VNA is based on Paul's or should be.
http://n2pk.com/
In the realm of "more toys' image next bench s/b a DC current source. Looked at the Hp6181c but best price seen $250. seemed high. Anyway thanks for input
Charles
 
#302
I have three junk military issue Tektronix limping along. I plan on scrapping them out for the 12A_7 tubes for pre-amp use. I also have a bench top HP, which has seen better days and is totally not calibrated. I am building a computer connected DIY / kit / spectrum analyzer. If it works out, I'll be using a 24bit/96k audio interface, the spec anal and software connected to an Apple laptop, scrapping all the old stuff. :smash:
 
#303
cowboy99 said:
I appreciate the feedback. I was looking for 2465B before when I fell for the pitch on TDS360; we'll see, I made end disliking digitals like most. I'll never part with the 5440; its my father's old scope; even have a new tube in reserves and a 2nd 5440 for parts.. I'm curious how one would go about adding more than the 3 pulg-ins; best swap-out for 5a22n would be to pull one of (2) 5a48 dual trace amps out: because I took your advice and quickly found/bought a 5a22n for $55.
The only avoidable VNA ( assume you mean vector network anal) I've read of is Paul Kiciak's, N2PK. Any others? I not real familiar it; but will be soon. It's my understanding any PC based VNA is based on Paul's or should be.
http://n2pk.com/
In the realm of "more toys' image next bench s/b a DC current source. Looked at the Hp6181c but best price seen $250. seemed high. Anyway thanks for input
Charles
Click to expand...

A programmable current source "is a terrible thing to waste" -- I have an old HP with the old style plug. Linear Tech has some wonderful ap-notes on on measuring, and Jung had an AX article a few months back on the topic.
 
#304
cowboy99 said:

The only avoidable VNA ( assume you mean vector network anal) I've read of is Paul Kiciak's, N2PK. Any others? I not real familiar it; but will be soon. It's my understanding any PC based VNA is based on Paul's or should be.
http://n2pk.com/

Charles
Click to expand...

That looks to be a very nice VNA project. But a decent amount of work. I use an HP 8601 sweep generator and AD 8307 log amp, analog scope in X,Y mode to test my 10.7 MHz IF filters. It was easy and quick to assemble.

AD8307 http://www.analog.com/en/rfif-components/log-ampsdetectors/ad8307/products/product.html

It could also be used to test caps etc.

Bob
 

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#309
1audio said:
Using a sound card w/ good FFT software is very appealing, however there are a few challenges. First is input conditioning. You need to protect the input from getting fried, you need to provide optimum range adjustment to get the full performance of the card and some type of passive analog output adjustment so the output signal is at its best performance. above the idea of using either an HP ACVTVM or and HP distortion analyzer for this were proposed and they both have merit. The ACVTVM however has too much internal distortion. It could be modified but it would be a big chore. The distortion analyzer has more potential but it needs careful review.
Alternatively an external passive attenuator, balanced, could be fabbed pretty easily and compensated for flat response. Adding a passive notch filter at a few key frequencies will extend the systems performance way down into the mud, limited only by the noise of the soundcard.
I have the Juli@ sound card which does 192/24 and seems to be close to the state of the art and only around $120.
Second challenge is software. I use Praxis and RMAA and get a lot of utility from them. However Praxis is pretty expensive and RMAA is not easy to use for anything other than soundcards. But its possible and RMAA is free.
Click to expand...


I agree that signal conditioning is a bit of a pain with the sound card solution. Thought this (TEKTRONIX 7A18 DUAL TRACE AMPLIFIER PLUGIN) might be a good start as a mechanical and switching solution, even if the electronics have to be replaced with a simple ultra low distortion solution. Nice to have a differential input option:
http://cgi.ebay.com/TEKTRONIX-7A18-...yZ104247QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
 
#310
advice?

Any thoughts on that Tm5006 Tek mainframe that Mark reduced down to $680. Price seems really good, I'm #2 inline on it.

Just apprehensive about the functionality of the programmable SG5010 oscillator with the manual AA501A analyzer. Hooking the SG5010's function to a sound card is an interesting possibility. Although mainframe has a problem, that's that much of a biggee.
Charles


1 Tek TM5006 Mainframe with $1000 ------> $680
1 SG5010 signal generator
1 AA501A Distortion analyzer
 
#311
If I were to use a Tek plug-in as a front end for scaling it would be a 7A22 or a 7A13 or a 5A21 (the cheap alternative) or a 1A7A. The Tek are very good but don't have the lowest distortion so they may need to be revised, not a small task when you look inside. You can download manual from the BAMA site to see what you are getting into. I'm about to construct an extender for a 7000 mainframe and I'm not looking forward to the task. These are very complicated boxes.

The TEK distortion analyzers are very good (the same key people went on to start AP). You can use them with a PC to good advantage. without any special fab. or software.
 
#320
After reading this looooong thread I have purchased an ebay HP 339A, and it looks almost new! Have prices dropped on these? I napped this one for $154. Last calibrated on 1997 so that pretty good I guess. HP stickers cover the rear panel screws, so I guess thats a sign no one has been inside turning trimmers since the calibration. Great! The ebayer didn't have very good pics, so I was very pleased with the new appearance. Only issue is that the OSC level control moves around alot. It's operation is correct and feels crisp, but it's sloppy at the front panel. Is this on a drive shaft like the others? If so the shaft support at knob need is loose. Can anyone tell me how it's supported up front, and the best way to access that area? I kinda hate to break the HP Cal. seals.....
 
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