Narda attenuator


militaryoperator
 

Before I use, are these big 150W 6Ghz attenuators bi or omni directional do you know?

Got an N socket on what I take to be front, with red label and chart and an N plug on rear. 

Ben.


Andy G4JNT
 

It will be labelled as such if it is NOT bidirectional
My Bird 1kW 30dB one isn't bidir, and has a big label on it to say so



On Thu, 6 May 2021 at 14:30, militaryoperator via groups.io <Military1944=aol.com@groups.io> wrote:
Before I use, are these big 150W 6Ghz attenuators bi or omni directional do you know?

Got an N socket on what I take to be front, with red label and chart and an N plug on rear. 

Ben.


Paul G8KFW
 

Hi  Ben

I have the Narda 150 W part number 769-30    ( - 30 dB ) and I use it into a HP power meter 

If yours is not 30 dB you will require extra attenuation on the output to go into a standard 100 mw power head

 

With the N female as the input this is the same end as the Rd label

The other end with the N mail goes to my power meter using a N barrel

Regards Paul

 

From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of militaryoperator via groups.io
Sent: 06 May 2021 14:31
To: ukmicrowaves@groups.io
Subject: [UKMicrowaves] Narda attenuator

 

Before I use, are these big 150W 6Ghz attenuators bi or omni directional do you know?

 

Got an N socket on what I take to be front, with red label and chart and an N plug on rear. 

 

Ben.


--
Paul Bicknell G8KFW   South Coast UK


militaryoperator
 

Hi  Ben
I have the Narda 150 W part number 769-30    ( - 30 dB ) and I use it into a HP power meter 
If yours is not 30 dB you will require extra attenuation on the output to go into a standard 100 mw power head
 
With the N female as the input this is the same end as the Rd label
The other end with the N mail goes to my power meter using a N barrel
Regards Paul

Thanks Paul, yes, 30db one and I have the 100mW head for my 6960. 

I'll use the red label as front then, hi. 

Cheers, Ben.


Dominique Dehays
 

Hi,

So it should be spécial fabrication, normaly the high power side should be the male connector.
73
Dom


Paul G8KFW
 

Hi Dom

Now you have me thinking must see if I can find a Narda catalogue

Ben did you get the attenuator from a local supplier to your home location ?

Regards Paul

 

From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of Dominique Dehays
Sent: 06 May 2021 15:57
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Narda attenuator

 

Hi,

 

So it should be spécial fabrication, normaly the high power side should be the male connector.

73

Dom

 


--
Paul Bicknell G8KFW   South Coast UK


Paul G8KFW
 

Hi just found this on the net still  looking for Narda book

 

Additional Features:

  • DC - 6 GHz
  • Type N connector
  • High Power
  • Bi-Directional
  • Attenuation dB (Nominal): 30
  • Attenuation dB (Deviation DC-2): ±0.5
  • Attenuation dB (Deviation 2-6): ±1.0
  • Power Input (Max Avg.): 150 W
  • Power Input (Max Peak): 3 kW
  • VSWR (max) DC-6 GHz: 1.35
  • Rugged design
  • Stainless steel connectors

The Narda 769-30 is a Type N, high power, bi-directional 30 dB fixed coaxial attenuator. The 769-30 features a broad frequency range (DC - 6 GHz), high power (150 Watts), rugged design and stainless steel connectors.

 

 

From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of Dominique Dehays
Sent: 06 May 2021 15:57
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Narda attenuator

 

Hi,

 

So it should be spécial fabrication, normaly the high power side should be the male connector.

73

Dom

 


--
Paul Bicknell G8KFW   South Coast UK


Paul G8KFW
 

Hi Ben   all OK but power rating is for it mounted horizontally  it was over 20 years ago that I bought it  

 

Type N High Power Bi-Directional Fixed Coaxial Attenuators y High Power y 3, 6, 10, 20 and 30 dB at 150 W y 10, 20, 30, 40, 50 and 60 dB at 100 W Specifications Type N (M/F), DC to 6 GHz, 150 W FREQUENCY RANGE (GHz) MODEL ATTENUATION (dB) POWER INPUT VSWR (max.) WEIGHT NOMINAL DEVIATION (max.) AVERAGE* (W max.) PEAK DC-2 2-6 (kW max.) lbs. kg. DC-6 769A-3 3 ±0.4 ±0.75 150 3 1.35 3.3 1.5 769A-6 6 ±0.4 ±0.75 150 3 1.35 3.3 1.5 769A-10 10 ±0.4 ±0.75 150 3 1.35 3.3 1.5 769A-20 20 ±0.5 ±1.00 150 3 1.35 3.3 1.5 769A-30 30 ±0.5 ±1.00 150 3 1.35 3.3 1.5

 

From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of Dominique Dehays
Sent: 06 May 2021 15:57
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Narda attenuator

 

Hi,

 

So it should be spécial fabrication, normaly the high power side should be the male connector.

73

Dom

 


--
Paul Bicknell G8KFW   South Coast UK


i2NDT
 

Ben,
you can check the resistance values according to this file: https://groups.io/g/UKMicrowaves/files/Attenuator%20check/Attenor.xls (you can find it in the file section, folder "Attenuator check"). if they comply with the values reported for a 30dB attenuator it is bidirectional...otherwise...we keep on searching!

best 73
de
i2NDT Claudio


i2NDT
 


Andy G4JNT
 

A non-bidirectional attenuator will still have the same resistance values measured from either end.   It is the power rating of the resistors on input and output sides that can differ to make it "non-directional".

In a single stage 30dB attenuator, the input resistor dissipates 94% of the power,  the middle resistor 6% and the third resistor just less than 0.1%
This applies to both pi and Tee configurations

I repeat - if a power attenuator is non a bidirectional one, then it will be labelled as such.




On Fri, 7 May 2021 at 07:31, i2NDT via groups.io <i2ndt=yahoo.it@groups.io> wrote:
Ben,
you can check the resistance values according to this file: https://groups.io/g/UKMicrowaves/files/Attenuator%20check/Attenor.xls (you can find it in the file section, folder "Attenuator check"). if they comply with the values reported for a 30dB attenuator it is bidirectional...otherwise...we keep on searching!

best 73
de
i2NDT Claudio


Dominique Dehays
 

Hi all,

Yes it is labeled but sometimes it is very discrete
73
Dom


militaryoperator
 

might this help?
_._,_._,_


Many thanks Paul and Claudio.  I think we are sorted now, bi it is. 

Ben G4BXD


i2NDT
 

good to know Andy!

I naively thought that high power uni-directional attenuators were a combination of several attenuators in series, such as a 3dB at the input followed by a 27dB, to distribute the thermal load on several devices.

Claudio


John Quarmby
 

A distributed attenuator of the type suggested by Claudio would certainly make the thermal design simpler and could be realised using thick film resistors on a BeO substrate. You could make a bidirectional version with graded sections at each end.

I had one of those nice 150W Narda attenuators but managed to blow it up, I do remember it being marked as containing BeO.

73

John G3XDY

On 07/05/2021 10:09, i2NDT via groups.io wrote:

good to know Andy!

I naively thought that high power uni-directional attenuators were a combination of several attenuators in series, such as a 3dB at the input followed by a 27dB, to distribute the thermal load on several devices.

Claudio

Virus-free. www.avast.com


Andy G4JNT
 

If you make the first such section a 6dB attenuator, the first shunt and series elements dissipate equal power.  Exactly one-third of the input power in each.
That is the case for PI or T topology.



On Fri, 7 May 2021 at 13:01, John Quarmby via groups.io <g3xdy=btinternet.com@groups.io> wrote:

A distributed attenuator of the type suggested by Claudio would certainly make the thermal design simpler and could be realised using thick film resistors on a BeO substrate. You could make a bidirectional version with graded sections at each end.

I had one of those nice 150W Narda attenuators but managed to blow it up, I do remember it being marked as containing BeO.

73

John G3XDY

On 07/05/2021 10:09, i2NDT via groups.io wrote:

good to know Andy!

I naively thought that high power uni-directional attenuators were a combination of several attenuators in series, such as a 3dB at the input followed by a 27dB, to distribute the thermal load on several devices.

Claudio

Virus-free. www.avast.com


 

Here is one of the type you refer to: appears to have 6 attenuator sections, 5 pi and one T (for some reason!) 27 dB total attenuation, 10W, and works well up to 6GHz. The left end is marked "input". 

On Fri, May 7, 2021 at 01:01 PM, John Quarmby wrote:

A distributed attenuator of the type suggested by Claudio would certainly make the thermal design simpler and could be realised using thick film resistors on a BeO substrate. You could make a bidirectional version with graded sections at each end.

I had one of those nice 150W Narda attenuators but managed to blow it up, I do remember it being marked as containing BeO.

73

John G3XDY

On 07/05/2021 10:09, i2NDT via groups.io wrote:

good to know Andy!

I naively thought that high power uni-directional attenuators were a combination of several attenuators in series, such as a 3dB at the input followed by a 27dB, to distribute the thermal load on several devices.

Claudio

Virus-free. www.avast.com