stacked attenuators...

[John Larkin]

I\'m intermittently doing some final FAT (first-article tests) on my
little toy pulse generator, but I\'m frying 20 dB attenuators. This
seems to help:

https://www.dropbox.com/s/w5dehb0jg0vgbfg/J270_Attn_Stack.jpg?raw=1

19 dB, close enough. I need to buy some high-power attenuators.

It doesn\'t help that the box\'s output SMA connector gets hot all by
itself.

Probably some ham has worked out optimum stacking of attenuators.

I wonder how it\'s possible to make a multi-GHz, hundreds of watts
attenuator. Big and fast don\'t usually go together.

 

[Lasse Langwadt Christensen]

torsdag den 27. august 2020 kl. 20.28.33 UTC+2 skrev John Larkin:

I\'m intermittently doing some final FAT (first-article tests) on my
little toy pulse generator, but I\'m frying 20 dB attenuators. This
seems to help:

https://www.dropbox.com/s/w5dehb0jg0vgbfg/J270_Attn_Stack.jpg?raw=1

19 dB, close enough. I need to buy some high-power attenuators.

It doesn\'t help that the box\'s output SMA connector gets hot all by
itself.

Probably some ham has worked out optimum stacking of attenuators.

I wonder how it\'s possible to make a multi-GHz, hundreds of watts
attenuator. Big and fast don\'t usually go together.

https://www.rf-microwave.com/en/anaren/h100na20x4/20db-chip-attenuator-with-flange-50/attc-h100na20/

https://www.ebay.co.uk/itm/232483634834

 

[John Larkin]

On Thu, 27 Aug 2020 12:18:49 -0700 (PDT), Lasse Langwadt Christensen
<langwadt@fonz.dk> wrote:

torsdag den 27. august 2020 kl. 20.28.33 UTC+2 skrev John Larkin:
I\'m intermittently doing some final FAT (first-article tests) on my
little toy pulse generator, but I\'m frying 20 dB attenuators. This
seems to help:

https://www.dropbox.com/s/w5dehb0jg0vgbfg/J270_Attn_Stack.jpg?raw=1

19 dB, close enough. I need to buy some high-power attenuators.

It doesn\'t help that the box\'s output SMA connector gets hot all by
itself.

Probably some ham has worked out optimum stacking of attenuators.

I wonder how it\'s possible to make a multi-GHz, hundreds of watts
attenuator. Big and fast don\'t usually go together.

https://www.rf-microwave.com/en/anaren/h100na20x4/20db-chip-attenuator-with-flange-50/attc-h100na20/

https://www.ebay.co.uk/itm/232483634834

I just ordered a couple of SMA 10-watt 3 GHz attenuators from Amazon,
about $20 each. It\'s amazing how much stuff Amazon has.

Engineering is now officially forbidden from going downstairs and
pulling parts from stock; we\'re supposed to make an email request and
wait to have them delivered. So we\'re getting a lot of resistor and
cap kits from Amazon, and lots of hardware and connectors too.

 

[whit3rd]

On Thursday, August 27, 2020 at 11:28:33 AM UTC-7, John Larkin wrote:

I wonder how it\'s possible to make a multi-GHz, hundreds of watts
attenuator. Big and fast don\'t usually go together.

For my microwave uses, it just takes a borosilicate measuring cup of water,
to keep the cavity from completely overpowering the fluorescent-lamp-under-test.

Attenuator is easy; measurement is harder.

 

[server]

On Thu, 27 Aug 2020 11:28:23 -0700, John Larkin
<jlarkin@highland_atwork_technology.com> wrote:

I\'m intermittently doing some final FAT (first-article tests) on my
little toy pulse generator, but I\'m frying 20 dB attenuators. This
seems to help:

https://www.dropbox.com/s/w5dehb0jg0vgbfg/J270_Attn_Stack.jpg?raw=1

19 dB, close enough. I need to buy some high-power attenuators.

It doesn\'t help that the box\'s output SMA connector gets hot all by
itself.

Probably some ham has worked out optimum stacking of attenuators.

I wonder how it\'s possible to make a multi-GHz, hundreds of watts
attenuator. Big and fast don\'t usually go together.

How many octave bandwidth do you need ?

I have used a 100 m reel of RG-58 coax as dummy load for frequencies
above 1 GHz. It doesn\'t matter if the other end is open, shorted or
terminated by 50 ohms .

If you are going to feed several watts, you might uncoil a few meters
of the reel, so the first meters of the coax will cool and not melt
due to the power losses.

If you need say 20 dB attenuation, use some coax and then use some low
power BNC/TNC/SMA attenuators after that.

 

[Phil Hobbs]

On 2020-08-27 17:15, upsidedown@downunder.com wrote:

On Thu, 27 Aug 2020 11:28:23 -0700, John Larkin
jlarkin@highland_atwork_technology.com> wrote:

I\'m intermittently doing some final FAT (first-article tests) on my
little toy pulse generator, but I\'m frying 20 dB attenuators. This
seems to help:

https://www.dropbox.com/s/w5dehb0jg0vgbfg/J270_Attn_Stack.jpg?raw=1

19 dB, close enough. I need to buy some high-power attenuators.

It doesn\'t help that the box\'s output SMA connector gets hot all by
itself.

Probably some ham has worked out optimum stacking of attenuators.

I wonder how it\'s possible to make a multi-GHz, hundreds of watts
attenuator. Big and fast don\'t usually go together.


How many octave bandwidth do you need ?

I have used a 100 m reel of RG-58 coax as dummy load for frequencies
above 1 GHz. It doesn\'t matter if the other end is open, shorted or
terminated by 50 ohms .

If you are going to feed several watts, you might uncoil a few meters
of the reel, so the first meters of the coax will cool and not melt
due to the power losses.

If you need say 20 dB attenuation, use some coax and then use some low
power BNC/TNC/SMA attenuators after that.

A load is much easier to make than a wideband attenuator. Skin-effect
loss makes the bandwidth of the line go like 1/length**2.

I don\'t do high-power RF stuff, but for the few-watt range, I often use
1 dB, 1 dB, 2 dB, 3 dB, then whatever more I need. That\'s good for
about four times the power rating of the individual pads. (I have a
couple of Mini Circuits 6 GHz SMA attenuator sets that I use a fair amount.)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[John Larkin]

On Fri, 28 Aug 2020 00:15:28 +0300, upsidedown@downunder.com wrote:

On Thu, 27 Aug 2020 11:28:23 -0700, John Larkin
jlarkin@highland_atwork_technology.com> wrote:

I\'m intermittently doing some final FAT (first-article tests) on my
little toy pulse generator, but I\'m frying 20 dB attenuators. This
seems to help:

https://www.dropbox.com/s/w5dehb0jg0vgbfg/J270_Attn_Stack.jpg?raw=1

19 dB, close enough. I need to buy some high-power attenuators.

It doesn\'t help that the box\'s output SMA connector gets hot all by
itself.

Probably some ham has worked out optimum stacking of attenuators.

I wonder how it\'s possible to make a multi-GHz, hundreds of watts
attenuator. Big and fast don\'t usually go together.


How many octave bandwidth do you need ?

I have used a 100 m reel of RG-58 coax as dummy load for frequencies
above 1 GHz. It doesn\'t matter if the other end is open, shorted or
terminated by 50 ohms .

If you are going to feed several watts, you might uncoil a few meters
of the reel, so the first meters of the coax will cool and not melt
due to the power losses.

If you need say 20 dB attenuation, use some coax and then use some low
power BNC/TNC/SMA attenuators after that.

I really need to see the waveforms accurately. My rise times are only
about 1 ns, so I don\'t need a super wideband attenuator.

My 500 MHz Rigol scope only tolerates 5v inputs when set to 50 ohms,
and my 20 GHz Tek only 2 volts. The little pulse generator can output
44v peak.

So I really need an accurate 40 dB attenuator that can soak up a few
watts. I can keep the duty cycle down some, but I do want to load the
DUT.

 

[Lasse Langwadt Christensen]

torsdag den 27. august 2020 kl. 23.38.37 UTC+2 skrev John Larkin:

On Fri, 28 Aug 2020 00:15:28 +0300, upsidedown@downunder.com wrote:

On Thu, 27 Aug 2020 11:28:23 -0700, John Larkin
jlarkin@highland_atwork_technology.com> wrote:

I\'m intermittently doing some final FAT (first-article tests) on my
little toy pulse generator, but I\'m frying 20 dB attenuators. This
seems to help:

https://www.dropbox.com/s/w5dehb0jg0vgbfg/J270_Attn_Stack.jpg?raw=1

19 dB, close enough. I need to buy some high-power attenuators.

It doesn\'t help that the box\'s output SMA connector gets hot all by
itself.

Probably some ham has worked out optimum stacking of attenuators.

I wonder how it\'s possible to make a multi-GHz, hundreds of watts
attenuator. Big and fast don\'t usually go together.


How many octave bandwidth do you need ?

I have used a 100 m reel of RG-58 coax as dummy load for frequencies
above 1 GHz. It doesn\'t matter if the other end is open, shorted or
terminated by 50 ohms .

If you are going to feed several watts, you might uncoil a few meters
of the reel, so the first meters of the coax will cool and not melt
due to the power losses.

If you need say 20 dB attenuation, use some coax and then use some low
power BNC/TNC/SMA attenuators after that.

I really need to see the waveforms accurately. My rise times are only
about 1 ns, so I don\'t need a super wideband attenuator.

My 500 MHz Rigol scope only tolerates 5v inputs when set to 50 ohms,
and my 20 GHz Tek only 2 volts. The little pulse generator can output
44v peak.

So I really need an accurate 40 dB attenuator that can soak up a few
watts. I can keep the duty cycle down some, but I do want to load the
DUT.

use a 50R dummy load and probe made with a 2.5K series resistor and coax
to a 50R terminated scope?

 

[Gerhard Hoffmann]

Am 27.08.20 um 23:56 schrieb Lasse Langwadt Christensen:

torsdag den 27. august 2020 kl. 23.38.37 UTC+2 skrev John Larkin:
On Fri, 28 Aug 2020 00:15:28 +0300, upsidedown@downunder.com wrote:


I really need to see the waveforms accurately. My rise times are only
about 1 ns, so I don\'t need a super wideband attenuator.

My 500 MHz Rigol scope only tolerates 5v inputs when set to 50 ohms,
and my 20 GHz Tek only 2 volts. The little pulse generator can output
44v peak.

So I really need an accurate 40 dB attenuator that can soak up a few
watts. I can keep the duty cycle down some, but I do want to load the
DUT.

use a 50R dummy load and probe made with a 2.5K series resistor and coax
to a 50R terminated scope?

<
https://www.flickr.com/photos/137684711@N07/50276655712/in/dateposted-public/lightbox/

I use the big black one when there comes more than I want.

In principle, I also have a really large KW size Bird dummy load
with -40 dB output, but one should never lend that stuff away.

And there are directional couplers.


Gerhard

 

[John Larkin]

On Fri, 28 Aug 2020 01:14:04 +0200, Gerhard Hoffmann <dk4xp@arcor.de>
wrote:

Am 27.08.20 um 23:56 schrieb Lasse Langwadt Christensen:
torsdag den 27. august 2020 kl. 23.38.37 UTC+2 skrev John Larkin:
On Fri, 28 Aug 2020 00:15:28 +0300, upsidedown@downunder.com wrote:


I really need to see the waveforms accurately. My rise times are only
about 1 ns, so I don\'t need a super wideband attenuator.

My 500 MHz Rigol scope only tolerates 5v inputs when set to 50 ohms,
and my 20 GHz Tek only 2 volts. The little pulse generator can output
44v peak.

So I really need an accurate 40 dB attenuator that can soak up a few
watts. I can keep the duty cycle down some, but I do want to load the
DUT.

use a 50R dummy load and probe made with a 2.5K series resistor and coax
to a 50R terminated scope?


https://www.flickr.com/photos/137684711@N07/50276655712/in/dateposted-public/lightbox/



I use the big black one when there comes more than I want.

In principle, I also have a really large KW size Bird dummy load
with -40 dB output, but one should never lend that stuff away.

And there are directional couplers.


Gerhard

I ordered a couple of these, 20 and 40 dB. I\'ll test them with my 20
GHz TDR/TDT scope and see how good they are.

https://www.amazon.com/gp/product/B07DXNRPKN/ref=ppx_yo_dt_b_asin_image_o00_s00?ie=UTF8&psc=1

 

[legg]

On Thu, 27 Aug 2020 12:38:26 -0700, John Larkin
<jlarkin@highland_atwork_technology.com> wrote:

On Thu, 27 Aug 2020 12:18:49 -0700 (PDT), Lasse Langwadt Christensen
langwadt@fonz.dk> wrote:

torsdag den 27. august 2020 kl. 20.28.33 UTC+2 skrev John Larkin:
I\'m intermittently doing some final FAT (first-article tests) on my
little toy pulse generator, but I\'m frying 20 dB attenuators. This
seems to help:

https://www.dropbox.com/s/w5dehb0jg0vgbfg/J270_Attn_Stack.jpg?raw=1

19 dB, close enough. I need to buy some high-power attenuators.

It doesn\'t help that the box\'s output SMA connector gets hot all by
itself.

Probably some ham has worked out optimum stacking of attenuators.

I wonder how it\'s possible to make a multi-GHz, hundreds of watts
attenuator. Big and fast don\'t usually go together.

https://www.rf-microwave.com/en/anaren/h100na20x4/20db-chip-attenuator-with-flange-50/attc-h100na20/

https://www.ebay.co.uk/itm/232483634834

I just ordered a couple of SMA 10-watt 3 GHz attenuators from Amazon,
about $20 each. It\'s amazing how much stuff Amazon has.

Engineering is now officially forbidden from going downstairs and
pulling parts from stock; we\'re supposed to make an email request and
wait to have them delivered. So we\'re getting a lot of resistor and
cap kits from Amazon, and lots of hardware and connectors too.

Bad idea. Use the same binned parts that paperwork and labor
determine will go in the product, or be surprised later.

RL

 

[server]

On Fri, 28 Aug 2020 09:06:03 -0400, legg <legg@nospam.magma.ca> wrote:

On Thu, 27 Aug 2020 12:38:26 -0700, John Larkin
jlarkin@highland_atwork_technology.com> wrote:

On Thu, 27 Aug 2020 12:18:49 -0700 (PDT), Lasse Langwadt Christensen
langwadt@fonz.dk> wrote:

torsdag den 27. august 2020 kl. 20.28.33 UTC+2 skrev John Larkin:
I\'m intermittently doing some final FAT (first-article tests) on my
little toy pulse generator, but I\'m frying 20 dB attenuators. This
seems to help:

https://www.dropbox.com/s/w5dehb0jg0vgbfg/J270_Attn_Stack.jpg?raw=1

19 dB, close enough. I need to buy some high-power attenuators.

It doesn\'t help that the box\'s output SMA connector gets hot all by
itself.

Probably some ham has worked out optimum stacking of attenuators.

I wonder how it\'s possible to make a multi-GHz, hundreds of watts
attenuator. Big and fast don\'t usually go together.

https://www.rf-microwave.com/en/anaren/h100na20x4/20db-chip-attenuator-with-flange-50/attc-h100na20/

https://www.ebay.co.uk/itm/232483634834

I just ordered a couple of SMA 10-watt 3 GHz attenuators from Amazon,
about $20 each. It\'s amazing how much stuff Amazon has.

Engineering is now officially forbidden from going downstairs and
pulling parts from stock; we\'re supposed to make an email request and
wait to have them delivered. So we\'re getting a lot of resistor and
cap kits from Amazon, and lots of hardware and connectors too.

Bad idea. Use the same binned parts that paperwork and labor
determine will go in the product, or be surprised later.

RL

There\'s not a lot of variation in 0805 1% resistors. I always have a
DVM and an LC meter in reach of my bench too.

The parts in a bin downstairs can come from various manufacturers too.

I\'m an engineer. I can deal with this sort of thing. The gain is low.
Do the math. Change the resistor. Now the gain is right.

Sample kits are great to have around. Amazon has some amazing stuff.

I keep a local stock of common parts, including ICs, in my office in
plastic bins, in coin envelopes. That saves time too.





--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard