¿ªÔÆÌåÓý

ctrl + shift + ? for shortcuts
© 2025 Groups.io
  1. Nanovna-Users
  2. Messages
Expanded Topics Messages
Date
Re: Cant fine Aivaible DFU Devices

 

Its working now, only with the laptop!
Re: Has anybody measured electron tubes

Jim Whartenby
 

Zack
Published S-parameters for a W-band TWT, Figure 5.
See:?
Regards,
Jim

Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy

-----Original Message-----
From: Zack Widup <w9sz.zack@...>
To: [email protected]
Sent: Tue, Jan 17, 2023 4:21 am
Subject: Re: [nanovna-users] Has anybody measured electron tubes

I have never seen any manufacturer publish s-parameters for tubes. And the
design techniques are different. The parts and methods used in biasing and
matching tubes are completely different than those used for FET's and
BJT's. The frequency ranges used for most commonly-available tubes do not
require s-parameters. There are very few tube amps around that operate
above 1296 MHz.

I see no reason to measure a tube on a VNA.

Zack W9SZ

On Mon, Jan 16, 2023 at 8:29 PM Leif M <leif.michaelsson@...> wrote:

I read about first TV sets and their tubes, thats history. And began to
wonder if anyone has measured tubes with VNAs. Do you get meaningfull
results. Connecting something with 200V supply voltage to NanoVna must be
interesting.
Re: Has anybody measured electron tubes

 

Yes, that's true. But what is the probability that the OP wants to test a
TWT?

Zack W9SZ

On Tue, Jan 17, 2023 at 8:21 AM Jim Lux <jimlux@...> wrote:

On 1/17/23 2:21 AM, Zack Widup wrote:
I have never seen any manufacturer publish s-parameters for tubes.
Pretty much every manufacturer of Traveling Wave Tubes publishes
S-parameters - In particular one tends to be interested in the S12
(reverse gain) at the second harmonic of the intended frequency band.

The other thing one tends to be very interested in is the group delay
across the band of operation, which is derived from data gathered with a
VNA.

I think you're thinking of gridded tubes like tri-, tetr-, and pent-odes.




And the
design techniques are different. The parts and methods used in biasing
and
matching tubes are completely different than those used for FET's and
BJT's. The frequency ranges used for most commonly-available tubes do not
require s-parameters. There are very few tube amps around that operate
above 1296 MHz.
I wouldn't be surprised if there are more microwave tube amps today than
HF band tube amps. If you want power, tubes are where it's at.



I see no reason to measure a tube on a VNA.

Zack W9SZ

On Mon, Jan 16, 2023 at 8:29 PM Leif M <leif.michaelsson@...>
wrote:

I read about first TV sets and their tubes, thats history. And began to
wonder if anyone has measured tubes with VNAs. Do you get meaningfull
results. Connecting something with 200V supply voltage to NanoVna must
be
interesting.

That's solved with just a DC block. A bigger issue is not blowing up
the VNA with the output power.
(and for the NanoVNA, the fact that the test signal is a square wave)
Re: Has anybody measured electron tubes

 

On 1/17/23 2:21 AM, Zack Widup wrote:
I have never seen any manufacturer publish s-parameters for tubes.
Pretty much every manufacturer of Traveling Wave Tubes publishes S-parameters - In particular one tends to be interested in the S12 (reverse gain) at the second harmonic of the intended frequency band.

The other thing one tends to be very interested in is the group delay across the band of operation, which is derived from data gathered with a VNA.

I think you're thinking of gridded tubes like tri-, tetr-, and pent-odes.




And the
design techniques are different. The parts and methods used in biasing and
matching tubes are completely different than those used for FET's and
BJT's. The frequency ranges used for most commonly-available tubes do not
require s-parameters. There are very few tube amps around that operate
above 1296 MHz.
I wouldn't be surprised if there are more microwave tube amps today than HF band tube amps. If you want power, tubes are where it's at.


I see no reason to measure a tube on a VNA.
Zack W9SZ
On Mon, Jan 16, 2023 at 8:29 PM Leif M <leif.michaelsson@...> wrote:

I read about first TV sets and their tubes, thats history. And began to
wonder if anyone has measured tubes with VNAs. Do you get meaningfull
results. Connecting something with 200V supply voltage to NanoVna must be
interesting.

That's solved with just a DC block. A bigger issue is not blowing up the VNA with the output power.
(and for the NanoVNA, the fact that the test signal is a square wave)
Re: Has anybody measured electron tubes

 

Most likely. In the really early days, there weren't any transistors that
worked above HF. Then some VHF transistors came along. There were no
high-frequency FET's in the early days. Now we have some FET's that work up
to 40 GHz. All my microwave designs using FET's have been on microstrip
transmission line printed on somewhat exotic substrates like Duroid 5880. I
have never seen a tube design that used microstrip.

Zack W9SZ

On Tue, Jan 17, 2023 at 6:58 AM Allasso <kevinhowjones@...> wrote:

"The frequency ranges used for most commonly-available tubes do not
require s-parameters. There are very few tube amps around that operate
above 1296 MHz."

I remember back in the day, using the giant round-screen tube oscilloscope
on the rollaround cart to measure high frequencies, because transistors
weren't fast enough. How things have changed. I can't remember if that
was before FETs came on the scene.
Re: Has anybody measured electron tubes

 

"The frequency ranges used for most commonly-available tubes do not
require s-parameters. There are very few tube amps around that operate
above 1296 MHz."

I remember back in the day, using the giant round-screen tube oscilloscope
on the rollaround cart to measure high frequencies, because transistors
weren't fast enough. How things have changed. I can't remember if that
was before FETs came on the scene.
Re: Has anybody measured electron tubes

 

I have never seen any manufacturer publish s-parameters for tubes. And the
design techniques are different. The parts and methods used in biasing and
matching tubes are completely different than those used for FET's and
BJT's. The frequency ranges used for most commonly-available tubes do not
require s-parameters. There are very few tube amps around that operate
above 1296 MHz.

I see no reason to measure a tube on a VNA.

Zack W9SZ

On Mon, Jan 16, 2023 at 8:29 PM Leif M <leif.michaelsson@...> wrote:

I read about first TV sets and their tubes, thats history. And began to
wonder if anyone has measured tubes with VNAs. Do you get meaningfull
results. Connecting something with 200V supply voltage to NanoVna must be
interesting.
Re: Measuring Bias-Tee

 

Yes, I did this kind of testing for HF to UHF range bias-T's. As others said, just connect 2 RF ports to to VNA ports, no DC of course. Look at S21 and S11.
I settled on 30 turns on FT37-43 for the choke, <1dB loss in 2-150MHz range.
Chinese units with SMD inductors work ok on VHF and UHF, add noticeable loss below 10MHz.

73, Mike AF7KR
Re: Has anybody measured electron tubes

 

You would do it the same way you would measure a high voltage MOSFET but
since
you are asking the question, I would not do it considering the voltages
involved.

On Tue, 17 Jan 2023 at 03:29, Leif M <leif.michaelsson@...> wrote:

I read about first TV sets and their tubes, thats history. And began to
wonder if anyone has measured tubes with VNAs. Do you get meaningfull
results. Connecting something with 200V supply voltage to NanoVna must be
interesting.
Re: Idea: Measuring parameters at different drive levels

 

On 1/16/23 6:23 PM, Leif M wrote:
Does any VNA measure and show parameters at different drive levels.
That's the kind of capability you get when you step up to the multi-thousand dollar level.

Active circuits saturate and class C amplifiers are not linear at all. Using different levels could give more and better information about the circuit.
Showing cloud of parameters like waterfall display in spectrum analysers, would tell usable range of the circuit (and require 3d display?).
Yes. and there's all kinds of interesting measurements and analyses possible.

If you look at the Keysight/Agilent/HP PNA analyzer literature, you'll see a lot of this kind of thing



Pulses, various amplitudes, etc.
Re: Idea: Measuring parameters at different drive levels

Jim Whartenby
 

DonIt seems that this thread is headed in the direction of Load Pull measurements.? Those interested can get a heads up here:,Jim
Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy

-----Original Message-----
From: Donald S Brant Jr <dsbrantjr@...>
To: [email protected]
Sent: Mon, Jan 16, 2023 8:32 pm
Subject: Re: [nanovna-users] Idea: Measuring parameters at different drive levels

Some high-end commercial units can do measurements at swept power levels, but none of the nanoVNA or its relatives.?
Also note that the nanoVNA stimulus is not sinusoidal but is a square wave, so active devices will not act the same as they will with a sine wave stimulus.?
In general they are not suitable for characterizing active devices,
73, Don N2VGU
Re: Has anybody measured electron tubes

 

You don't seem to understand the NanoVNA is in NO Way a tube tester.
Clyde Lambert KC7BJE
Re: Has anybody measured electron tubes

 

Tube tester is a different tool, I agree. But has anybody even measured s-params of a tube. And all without burning the VNA.
Re: Idea: Measuring parameters at different drive levels

 

Oh. Does NanoVna2 also use squarewave measuring signal? I mainly use V2 Plus4

Yes, any NanoVna would require large HW changes I think. Maybe sometime.
Re: Has anybody measured electron tubes

 

The Wrong tool for that Job!??
Kent

On Monday, January 16, 2023 at 08:29:46 PM CST, Leif M <leif.michaelsson@...> wrote:

I read about first TV sets and their tubes, thats history. And began to wonder if anyone has measured tubes with VNAs. Do you get meaningfull results. Connecting something with 200V supply voltage to NanoVna must be interesting.
Re: Has anybody measured electron tubes

 

Testing tubes cannot be done with the nanoVNA.

I have tested plenty of tubes, various types etc, using a tube tester designed to provide appropriate voltages to the correct pins to bias the tubes and measure emission.

Should you need to test tubes there are testers that can be found either complete or as kits to build.

Tim VK4TIM.

Sent from my Iphone.

On 17 Jan 2023, at 12:29, Leif <leif.michaelsson@...> wrote:

?I read about first TV sets and their tubes, thats history. And began to wonder if anyone has measured tubes with VNAs. Do you get meaningfull results. Connecting something with 200V supply voltage to NanoVna must be interesting.
Re: Idea: Measuring parameters at different drive levels

 

Some high-end commercial units can do measurements at swept power levels, but none of the nanoVNA or its relatives.
Also note that the nanoVNA stimulus is not sinusoidal but is a square wave, so active devices will not act the same as they will with a sine wave stimulus.
In general they are not suitable for characterizing active devices,
73, Don N2VGU
Has anybody measured electron tubes

 

I read about first TV sets and their tubes, thats history. And began to wonder if anyone has measured tubes with VNAs. Do you get meaningfull results. Connecting something with 200V supply voltage to NanoVna must be interesting.
Re: Idea: Measuring parameters at different drive levels

 

My 8510 does, but then it's 100 kg heavier than the Nano.? Kent

On Monday, January 16, 2023 at 08:23:39 PM CST, Leif M <leif.michaelsson@...> wrote:

Does any VNA measure and show parameters at different drive levels.
Active circuits saturate and class C amplifiers are not linear at all. Using different levels could give more and better information about the circuit.

Showing cloud of parameters like waterfall display in spectrum analysers, would tell usable range of the circuit (and require 3d display?).
Idea: Measuring parameters at different drive levels

 

Does any VNA measure and show parameters at different drive levels.
Active circuits saturate and class C amplifiers are not linear at all. Using different levels could give more and better information about the circuit.

Showing cloud of parameters like waterfall display in spectrum analysers, would tell usable range of the circuit (and require 3d display?).
9221 - 9240 of 39640