Look at the definitions of the 4 S parameters
S22 is the reflection of signal reflected by the load. That is a major source of instability.
On Sunday, October 29, 2023 at 01:32:44 PM CDT, Jinxie <paul666@...> wrote:
OK, but this only works for passive DUTs, one assumes? If you're testing an RF amplifier - for example - then it's not going to work, is it?
|
To rotate the device in a two parameters VNA works for any device. No matter if it’s active or passive . Unless you power the device via his ?ports. ? To rotate the device adds more uncertainly to mesurement because you have a couple of connector connections more. It is important depending on applications.?
Ing. Patricio A. GrecoTaller Aeronáutico de Reparación 1B-349Organización de Mantenimiento Aeronáutico de la Defensa OMAD-001Gral. Martín Rodríguez 2159San Miguel (1663)Buenos AiresT:?+5411-4455-2557F:?+5411-4032-0072
toggle quoted message
Show quoted text
On 29 Oct 2023, at 15:32, Jinxie <paul666@...> wrote:
?OK, but this only works for passive DUTs, one assumes? If you're testing an RF amplifier - for example - then it's not going to work, is it?
|
OK, but this only works for passive DUTs, one assumes? If you're testing an RF amplifier - for example - then it's not going to work, is it?
|
Yes. It's inconvenient, so higher grade VNAs have relay boxes to automate the task or more receivers and directional couplers.
I was building such a setup for my VNWA and then wound up with an 8753B and 85046A S parameter set (the switch box)
Have Fun!
Reg On Sunday, October 29, 2023 at 12:30:29 PM CDT, Jinxie <paul666@...> wrote:
Is that seriously all there is to it?
|
Is that seriously all there is to it?
|
Turn the DUT 180 degrees.
On Sunday, October 29, 2023 at 09:19:11 AM CDT, Jinxie <paul666@...> wrote:
Hi,
Is there any work-around you can use to measure S12 and S22 using a cheapo VNA which is primarily designed only to provide S11 and S21 data?
Thanks.
J.
|
Hi,
Is there any work-around you can use to measure S12 and S22 using a cheapo VNA which is primarily designed only to provide S11 and S21 data?
Thanks.
J.
|
Re: Marconi Q meter exciter - update
A number of instruments used the same indicators so you should find them fairly easily.
Regards? Nigel Adams-Marconi Instruments Heritage Collection?
toggle quoted message
Show quoted text
On 28 Oct 2023, at 17:09, swallowp@... via groups.io <swallowp@...> wrote:
?Following my July post [1], I got round to realising the exciter in a 100 x 100 x 50mm extruded aluminium enclosure powered by an external 7 - 12V "wall wart".? Power draw is about 2.5W. RF output 40kHz to 55MHz is more than +14dBm, all harmonics and spurs <30dBc, adquate for my purposes with the TF1245A injection transformer modification [2].? ALC provides a constant output level across the whole frequency range which really simplifies searching for a resonance by frequency.? Tuning is continuous in 1Hz to 1MHz decade steps with up-down buttons to change the step size on the fly. Signal source: ???? AD9850 DDS Filter:??? ??? ??? 7 section elliptic, 62MHz corner frequency Amplifier:??? ??? ??? AD603 variable gain amplifier, 2N3904 fixed gain driver with some frequency compensation Power amplifer:??? ??? 2 x 2N5109 White follower run from +13.6V rail Levelling loop:??? ??? AD8307 log detector, LM358 amp/comparator (overkill, but provides very fine adjustment) Power conditioning:??? +13.6V boost, +5V buck converters with additional filtering on outputs Controller:??? ??? 8MHz Arduino Pro-mini The design is based on elements I had to hand or had prototyped for other projects, there are probably better and/or lower cost ways to realise it. ? That said, the result is a Q meter outfit that is a pleasure to use with respect to amplitude and frequency stability/readability/repeatability without taking up much space.? It also preserves a fine piece of Marconi engineering as a working instrument that I had purchased as scrap to break up for its RF deck.? Now I want a Marconi power indicator lamp holder and bezel to improve its appearance... PeterS??? G8EZE [1]??? Marconi Q meter exciter? post #1811 July 2023 [2]??? Marconi Q meter exciter? posts #1703, 1709 May 2023
<Q meter exciter front panel.JPG> <TF1245A and exciter in use.JPG>
|
Re: Marconi Q meter exciter - update
Following my July post [1], I got round to realising the exciter in a 100 x 100 x 50mm extruded aluminium enclosure powered by an external 7 - 12V "wall wart".? Power draw is about 2.5W.
RF output 40kHz to 55MHz is more than +14dBm, all harmonics and spurs <30dBc, adquate for my purposes with the TF1245A injection transformer modification [2].? ALC provides a constant output level across the whole frequency range which really simplifies searching for a resonance by frequency.? Tuning is continuous in 1Hz to 1MHz decade steps with up-down buttons to change the step size on the fly.
Signal source: ???? AD9850 DDS
Filter:??? ??? ??? 7 section elliptic, 62MHz corner frequency
Amplifier:??? ??? ??? AD603 variable gain amplifier, 2N3904 fixed gain driver with some frequency compensation
Power amplifer:??? ??? 2 x 2N5109 White follower run from +13.6V rail
Levelling loop:??? ??? AD8307 log detector, LM358 amp/comparator (overkill, but provides very fine adjustment)
Power conditioning:??? +13.6V boost, +5V buck converters with additional filtering on outputs
Controller:??? ??? 8MHz Arduino Pro-mini
The design is based on elements I had to hand or had prototyped for other projects, there are probably better and/or lower cost ways to realise it. ?
That said, the result is a Q meter outfit that is a pleasure to use with respect to amplitude and frequency stability/readability/repeatability without taking up much space.? It also preserves a fine piece of Marconi engineering as a working instrument that I had purchased as scrap to break up for its RF deck.? Now I want a Marconi power indicator lamp holder and bezel to improve its appearance...
PeterS??? G8EZE
[1]??? Marconi Q meter exciter? post #1811 July 2023
[2]??? Marconi Q meter exciter? posts #1703, 1709 May 2023
|
Re: Multiplexing 3457A using a 3497A ?
I have a 3497A with built in 5 ? digit meter.
?
Sent from for Windows
?
|
Re: Multiplexing 3457A using a 3497A ?
If you decide to use I2C anywhere, there's an I2C isolator chip, ISO1641 that has a fair bit of voltage isolation.? AVRs can do I2C reasonably well.? If you go serial, then likely standard optoisolators would do do better because of the unidirectional lines.? There's a USB_GPIB master project on Github, that is exactly what it says.? There's also a GPIB adaptor that can use an arduino shield and drive GPIB.? That may be your better bet if you decide to go that way.
Harvey
toggle quoted message
Show quoted text
On 9/10/2023 1:09 PM, John Griessen wrote: "
I think there's a strong case for replacing the inguard controller with an ATMega shield with the requisite >connections and signals.? I don't like the architecture, but the 5 V TTL compatibility is very valuable.
Measuring any of 100 voltage sources? with any arbitrary meter seems to me a very useful facility.? Especially >if you could use it with 3497A GPIB commands or solder headers in place, connect an ATMega and run bespoke >code on that."
I like the idea of using the Atmel uC based GPIB, (built in or grafted on), to do the special task.
Is the inguard controller part of the DVM or the 3497A?
I have not read the manuals yet.?? Can the 3497A GPIB be the controller of the 3457A and also receive commands for sequence of actions from a laptop?? If so, command the 3457A relay card to use a set of wires, issue commands to relay cards in the 3497A, and get
A * B sets of measurement terminals to use by program.
|
Re: Multiplexing 3457A using a 3497A ?
" I think there's a strong case for replacing the inguard controller with an ATMega shield with the requisite >connections and signals. I don't like the architecture, but the 5 V TTL compatibility is very valuable. Measuring any of 100 voltage sources with any arbitrary meter seems to me a very useful facility. Especially >if you could use it with 3497A GPIB commands or solder headers in place, connect an ATMega and run bespoke >code on that." I like the idea of using the Atmel uC based GPIB, (built in or grafted on), to do the special task. Is the inguard controller part of the DVM or the 3497A? I have not read the manuals yet. Can the 3497A GPIB be the controller of the 3457A and also receive commands for sequence of actions from a laptop? If so, command the 3457A relay card to use a set of wires, issue commands to relay cards in the 3497A, and get A * B sets of measurement terminals to use by program.
|
Re: Suitable N Connectors for Gore PhaseFlex RF Cable
Thanks for the comment. Yes, I agree it can't be trivial to terminate these cables, particularly with excellent return loss at 10 or more gigahertz that some are rated, but yet it is being done at the factory every day, I wish I had a failed cable to disassemble and look at the way the connector is installed to satisfy my curiousity. I do have a feeling they are custom connectors that are not readily available.
|
Interesting idea to split it up—get two (or three) caps for the price of one. I'm imagining a couple of selector switches to pick the positions of the decade divisions, then a couple more switches to allow combining those sections... Yeah...more parasitics, yay.
|
Re: Suitable N Connectors for Gore PhaseFlex RF Cable
My experience as well. Especially with the higher frequency/cost Cables. ? Ross ?
toggle quoted message
Show quoted text
From: [email protected] < [email protected]> On Behalf Of Jeff Kruth via groups.io Sent: Wednesday, September 06, 2023 7:29 AM To: [email protected]Subject: [Test Equipment Design & Construction] Suitable N Connectors for Gore PhaseFlex RF Cable ? Wow. I have never seen anyone put connectors on a piece of Gore cable and have the result be worth a damn! Many Gore cables with end severed/ripped off or broken have been canned over the years at the facilities I worked at. No dependable method of termination. Good luck!
|
Hi, ? A good source of Precision Capacitors is Oscilloscope Horizontal Time / Division Timing Capacitors. A lot of the Tektronix TM500 Frequency/Pulse Function Generators use the same set of set of precision timing Capacitors. Most of the ones I have used are Tektronix Oscilloscope parts off of ebay. Precision Timing Capacitors are used in other R-C Type Test Equipment Brands like HP, Krohn-Hite, etc. ? Some can be had in nice even decades with good accuracy and repeatability over temperature. Being used, they have already gone through temperature cycling and gross aging process.. ? They are also inexpensive and available compared with new purchased parts. ? I find Precision Resistors from similar equipment above and Older Analog Meter (like Simpson and Triplett), Range Switching Resistors. These have also been temperature cycled and aged. ? In all of the components above, you obviously need to test them and make sure they meet your application. ? The packages of the Timing Capacitors are large, the Resistors are generally Wire-Wound type. If your application if for High Frequency work, the parasitics will interfere with the value over Frequency. ? As with all devices, construction is key. If you look at a General Radio Substitution Decade Box (any kind – R/L or C), their Decade Rotary Switches are very deliberate with massive contact pads and include a lot of distance between them, the Armature Arm is really big with controlled pressure (additional spring element). This is to reduce Resistance and parasitics plus ensure accuracy and repeatability. ? The wiring is large AWG with lots of separation distance for minimum Capacitance Coupling and Mutual Inductance effects (remember all components tie to a common Ground). In a Resistance Decade for instance, the actual Resistor components are Wire-Wound on Glass formers for low parasitics and provide heat dissipation. The External 5-way Binding Posts are of high quality and there is a Grounding Strap bar to allow separation or tying the Ground to Chassis for low noise applications, too. ? The enclosures are generally full metal to prevent EMI Susceptibility with the components and interconnect wiring. ? Even then, with all of this design, they are made for low frequency applications. ? ? The HP Precision Calibration Capacitor Kit (for my HP4192A), have plug-on modules with individual precision components inside interconnected to 4 modified BNC Connectors. The HP4192A is Kelvin Contact designed where a High-Side and Low-Side Source is supplied on two BNCs and measurements are performed with the other High-Side and Low-Side BNCs. The Components internal to the module are precision Polystyrene and other type Capacitors. ? ? ? If you are going to make your own, these are just some of the ideas you might consider for your journey. ? ? Thanks for listening, Ross ?
toggle quoted message
Show quoted text
From: [email protected] < [email protected]> On Behalf Of tgerbic Sent: Tuesday, September 05, 2023 9:41 PM To: [email protected]Subject: Re: [Test Equipment Design & Construction] Cap sub box ? I have built and repaired several resistor and cap substitution boxes, plus calibrated strings of resistors to make accurate voltmeter ranges.? Accuracy can be had, with a bunch of effort, tuning range settings one by one. I use a spreadsheet that allows me to put in the desired value and one measured value and tell me what to put in parallel or series to get the desired value. Also use a spreadsheet that allows me to put up to five values in parallel to get a desired value.? I think there are at least six calculators on the sheet to get different configurations done.? The calculators are pretty simple to make and use basic math. The problem is the time it takes to get the accuracy I want. While I have all the E96 resistors to tune a resistance string, cap values take a lot more work and cost.? Another thing I do is assume a lowest possible value. Probably 5pf or so for capacitors and, and .1ohms or .01 ohms for resistors, since the wiring, voltage/current ratings of switches and switching limits the lowest level that can be reached.? Then I tune upwards trying to get the values as close as possible.? Another thing that makes this hard to design is having problems with voltage ratings for caps and wattage ratings for resistors.?
This looks like a great endeavour and works pretty good.? I would however suggest you split the decades into values up to 1uf and 1uf and above. Use two sets of binding posts and have a shorting bar or switch to tie them together if you need more granularity around the center of the ranges. At either end of the ranges, use the set of binding posts for the high or low ranges. ? I think this will help in usage situations.? Keep in mind that 10pf will make little difference, for example, when you are working with 10uF.
Most of the home built capacitor decade boxes I have seen are not very granular or accurate, only a little faster than jumping in individual capacitors.? Where I see a good use for the lower ranges in yours is for things like filter designs where you can really tune in the values and see what is happening in a real circuit.? Even if they are off a little, the general granularity with allow you to see small changes.? Also today finding some of the values can be real hard that you could just dial in with your decade box. How easy is it to get a .075uf or .75uf cap? Or even most 56x, 68x or 86x values better than 5%??? Another area that your box would be good to use might be troubleshooting old test equipment, for example old capacitor checkers.? Many use caps that are multiples of 2.0uf 1% or 2%.? A 2.00uf value could be dialed in on your box (connected to a cap meter).
Sorry for the long winded response but I like the general design and can see some useful use cases for this device. So not necessarily pointless.
Tony
|
Suitable N Connectors for Gore PhaseFlex RF Cable
Wow. I have never seen anyone put connectors on a piece of Gore cable and have the result be worth a damn! Many Gore cables with end severed/ripped off or broken have been canned over the years at the facilities I worked at. No dependable method of termination. Good luck!
Jeff Kruth
|
You have a new follower!
With best regards
Tam HANNA
Enjoy electronics? Join 21k4 other followers by visiting the Crazy Electronics Lab at
On 2023. 09. 05. 23:48, Michael Dunn
wrote:
toggle quoted message
Show quoted text
My recent, fairly pointless, but lots of fun, project :-)
|
I recently completed restoring several Eico 3 decade and General radio 5 decade capacitance boxes.? While the GR units were very accurate (they were sold as precision units) surprisingly the Eico units rarely had over a percent error.? It may be worth checking the auction sites as these seem to come available fairly frequently and for a reasonable amount.
Hal
|
I have built and repaired several resistor and cap substitution boxes, plus calibrated strings of resistors to make accurate voltmeter ranges.? Accuracy can be had, with a bunch of effort, tuning range settings one by one. I use a spreadsheet that allows me to put in the desired value and one measured value and tell me what to put in parallel or series to get the desired value. Also use a spreadsheet that allows me to put up to five values in parallel to get a desired value.? I think there are at least six calculators on the sheet to get different configurations done.? The calculators are pretty simple to make and use basic math. The problem is the time it takes to get the accuracy I want. While I have all the E96 resistors to tune a resistance string, cap values take a lot more work and cost.? Another thing I do is assume a lowest possible value. Probably 5pf or so for capacitors and, and .1ohms or .01 ohms for resistors, since the wiring, voltage/current ratings of switches and switching limits the lowest level that can be reached.? Then I tune upwards trying to get the values as close as possible.? Another thing that makes this hard to design is having problems with voltage ratings for caps and wattage ratings for resistors.?
This looks like a great endeavour and works pretty good.? I would however suggest you split the decades into values up to 1uf and 1uf and above. Use two sets of binding posts and have a shorting bar or switch to tie them together if you need more granularity around the center of the ranges. At either end of the ranges, use the set of binding posts for the high or low ranges. ? I think this will help in usage situations.? Keep in mind that 10pf will make little difference, for example, when you are working with 10uF.
Most of the home built capacitor decade boxes I have seen are not very granular or accurate, only a little faster than jumping in individual capacitors.? Where I see a good use for the lower ranges in yours is for things like filter designs where you can really tune in the values and see what is happening in a real circuit.? Even if they are off a little, the general granularity with allow you to see small changes.? Also today finding some of the values can be real hard that you could just dial in with your decade box. How easy is it to get a .075uf or .75uf cap? Or even most 56x, 68x or 86x values better than 5%??? Another area that your box would be good to use might be troubleshooting old test equipment, for example old capacitor checkers.? Many use caps that are multiples of 2.0uf 1% or 2%.? A 2.00uf value could be dialed in on your box (connected to a cap meter).
Sorry for the long winded response but I like the general design and can see some useful use cases for this device. So not necessarily pointless.
Tony
|
Patricio A. Greco
Jinxie
Michael Dunn
Harold Foster