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Author Topic: Noise head, noise diode.  (Read 5470 times)
VE6TWN
Member

Posts: 6




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« on: June 10, 2011, 12:58:18 PM »

Hi,

I am thinking to build one or few noise head and I am trying to source the noise diode NC302L or NC303.
However, there's minimun order for this diode and I don't need that many.
Does any one find a source who will accept small order (2 pcs) in decent price?
OR if you want to build the noise head too then I can try to arrage a minimum order. The minimum order will be around 7 pcs, I would like to buy two of them, so I will need find people who want the remaing diodes.
I have tried few other diodes and they are not really what I want.
If anyone has better idea about the noise head, please share your idea.
Thanks.

Jacky
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KL0S
Member

Posts: 132




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« Reply #1 on: June 10, 2011, 05:02:27 PM »

Jacky – I worked with the Noise/Com company a while back to get several NC302L diodes to build Bill Sabin's homebrew noise sources without having to meet the minimum purchase requirement as they have been obliging to hams.  It took several phone calls and had to work with a sales rep but I prevailed and posted the following to the emrfd Yahoo group….whether this is still valid or not I'm not sure but worth a try.  Here's what I found out:

"Guys -- I was just notified that Noisecom has approved waiving the $250 minimum order and will sell the NC302L noise diodes in small quantities to hams.  Just placed an order for a couple; they are $28 a piece.

You can order from Noisecom by calling:

(973) 386-9696 and then choose "1" and "1" at the two prompts to get to Carolyn in the sales department.  Let her know you're a ham and she'll be glad to help.  They take credit cards.

I'm not sure if the calibration offer is still available but hopefully the offer made a couple of years ago is still valid.

Anyway, nice people to work with....tell them you appreciate them making an exception for us....goodwill always goes a long way!"

Additionally, they MAY still be doing calibration for hams as well….at least as of July 2008 according to Gary WB9JPS back in 2008:

From: "Gary Johnson" <gwj@spamcop.net>
Date: July 11, 2008 10:35:18 AM EDT
To: emrfd@yahoogroups.com
Subject: [emrfd] Re: Noise Figure Measurement without a Spectrum Analyzer
Reply-To: emrfd@yahoogroups.com

Some good news: Noise Com is calibrating sources again (as least for US customers). This is from an email forwarded to me by Bill Sabin:

As you are well aware, in business terms 1994 was a long time ago. Noise/Com to this day continues to offer Amateur Radio Experimenters discounts on diodes. Calibrations of these Noise Sources have been more a factor of available resources. After review of your request, on a trial basis we will resume our offer to calibrate these noise sources at a substantial discount. Pricing will need be $100.00, turn around time will be a function of available resources and will most likely be quoted at 8 - 12 weeks. This will be for domestic customers only, as we have had too many issues with noise sources being held up in customs. Customers will need to contact Noise/Com for an RMA (Return Merchandise Authorization).

Best Regards,
Al Sebolao
Sales Manager
Noise/Com
25 Eastmans Road
Parsippany, NJ 07054
(973) 386-9696 Voice
(973) 386-9191 Fax

-Gary, WB9JPS

Hope this helps.

73 – Dino KL0S
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VE6TWN
Member

Posts: 6




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« Reply #2 on: June 10, 2011, 07:59:51 PM »

Dino,

Thank you all the help and information you have here.
Actually I phoned Noisecom today and the lady on the other side told me she is only taking the order and she doesn't know anything about HAM discount stuff. She also gave me the Canada contact information.
When I contacted the Canada rep.they told me the same thing, there's no HAM discount and there's minimum order, price is 42% more each.
Anyway, make long story short, I think I will contact Noisecom again and see if I can buy few pieces from them.

You mentioned that you have worked on NC302L a while back, how were these diodes performed? what's the ENR you got and how's the response flatness? Do you have any data can share?
Thanks.

Jacky
 
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KA4POL
Member

Posts: 1969




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« Reply #3 on: June 11, 2011, 12:28:40 AM »

In the ARRL Handbook 2010 on pages 25.26 and 25.27 it is mentioned that NOISE/COM has agreed to make the NC302L diodes available to amateur experimenters for the special price of $ 10 each. They also will calibrate home-built units for $ 25 plus shipping. That sounds great. However, I tried to order diodes and did not receive a reply at all.
I built a circuit using a simple Zener diode which does not perform over the same large frequency range but certainly is good enough for up to 200 MHz.
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KL0S
Member

Posts: 132




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« Reply #4 on: June 12, 2011, 07:39:42 AM »

Jacky - well, the diodes to construct the noise sources are still in my projects queue! At the time I got my set of diodes from NoiseCom they were $28 each. The trick is working thru the system until you find someone who in fact is familiar with the discount they were giving. Now, the answer may be "Yes, we can do that" or "Yes, we used to give a discount but no longer do" but until you get that kind of answer I would keep trying. Here's the text of what I ended up providing the sales rep that I had to work thru before the company HQ finally acknowledged that they would honor their deal:

Matt -- thanks so much for taking my call.  Here's a synopsis that may be helpful for you to understand what I (and others) are interested in.

--In 1994 William Sabin described "A Calibrated Noise Source for Amateur Radio" in QST magazine, the monthly publication of the American Radio Relay League (ARRL) [http://www.arrl.org/] (.pdf file of original article attached).

--Bill's projects (two versions 0.5-500MHz and 1-2500MHz) have been reprinted over the years and many "homebrew" versions have been constructed by hams.

--Noisecom has in the past made the noise diode, the NC302L, available to ham radio operators in small quantities (1-2), not subject to the normal minimum purchase requirement.

--Additionally, your company has as a good (make that great) goodwill gesture, provided very low-cost calibration service for these units if the builder desired.

From a 2008 e-mail:

Some good news: Noise Com is calibrating sources again (as least for US customers). This
is from an email forwarded to me by Bill Sabin:

As you are well aware, in business terms 1994 was a long time ago. Noise/Com
to this day continues to offer Amateur Radio Experimenters discounts on
diodes. Calibrations of these Noise Sources have been more a factor of
available resources. After review of your request, on a trial basis we will
resume our offer to calibrate these noise sources at a substantial discount.
Pricing will need be $100.00, turn around time will be a function of
available resources and will most likely be quoted at 8 - 12 weeks. This
will be for domestic customers only, as we have had too many issues with
noise sources being held up in customs. Customers will need to contact
Noise/Com for an RMA (Return Merchandise Authorization).

Best Regards,
Al Sebolao
Sales Manager
Noise/Com
25 Eastmans Road
Parsippany, NJ 07054
(973) 386-9696 Voice
(973) 386-9191 Fax

There is still a good deal of interest in the project and it would be great if we could still purchase these diodes in small quantities to allow more of us to build Bill's great project for use at our own workbenches.  As a matter of fact it was discussed today on one of the experimenters' Internet reflectors and prompted me to call -- this project in its two versions has been in "the queue" for some time and I'd like to get started.

Thanks much in advance!

Dino Papas
Colonel U.S. Army, Retired
Amateur Radio Operator KL0S

Let us know if you make any progress as there may be others who are still interested.

73 - Dino KL0S
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VE6TWN
Member

Posts: 6




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« Reply #5 on: June 13, 2011, 12:38:45 PM »

Just phoned Al and looks like they stop doing discount for HAM.
I guess I will have to find something else to do the noise source.

Jacky
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W0BTU
Member

Posts: 1651


WWW

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« Reply #6 on: June 16, 2011, 03:05:06 AM »

Please forgive my ignorance, but I don't understand what a "noise head" is.

Are you trying to build a noise generator?

If so, for what bands?

FWIW, I found out many years ago that a very inexpensive Zener diode makes a wonderful noise generator. I built mine for my 144 MHz SSB/CW station.
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W6RMK
Member

Posts: 650




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« Reply #7 on: June 17, 2011, 10:01:04 AM »

The difference between using a special noise diode and any old diode (as W0BTU mentions, a zener makes a fine noise source) is that the noise diode typically has better spectral flatness and has really good stability over time/temperature. 

You can use a diode noise source as a calibration standard (once you've calibrated it against a primary standard) for a lot of years in a lot of situations.  I had a thermally controlled noise diode source at 13GHz at work (about 7000k, 13 dB ENR nominal, a bit hotter actually) which stable to a few kelvins over a week hooked up to the NIST test rig. 

There are also thermionic noise sources (noise tubes) which are very stable over time.

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WD4HXG
Member

Posts: 182




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« Reply #8 on: July 16, 2011, 04:31:43 AM »

Jacky and Dino. Contact me off list at
wcmoore@verizon.net. I may be able
to access a limited number of NC302L-BL
in onesey-twosey quantities. These are
the rectangular packages with flat leads
intended for surface mount applications.

Chuck
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WD4HXG
Member

Posts: 182




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« Reply #9 on: July 31, 2011, 02:07:01 PM »

Please forgive my ignorance, but I don't understand what a "noise head" is.

Are you trying to build a noise generator?

If so, for what bands?

FWIW, I found out many years ago that a very inexpensive Zener diode makes a wonderful noise generator. I built mine for my 144 MHz SSB/CW station.

If you use the older HP 342, more current HP8970A and some other
Noise Figure Meters the source of noise for tests is not integral to
the Noise Figure Meter. Rather a separate module containing a
Noise Diode is used. This allows you to connect the Noise Source
directly to the DUT (Device Under Test). In many labs techs and
engineers call the Noise Source a Noise Head as when it is attached
to the Noise Figure Meter there is a cable from the Meter to the
Noise Source which supplies power. It looks somewhat like a snake
with an enlarged head.

Noise Sources (aka Heads) can use either a vacuum tube diode or
a solid state diode to generate the Excess Noise for testing. The older
HP342 was provisioned to use either the tube or silicon noise diode
with separate connectors for each.  In general Noise Figure Meters
are speced to work with Noise Sources which provide Excess Noise
rated at 15 dB nominal. The older 342 had to be calibrated at each
test frequency manually. The more modern HP8970A was calibrated
at each test frequency and the information stored in memory inside
the test instrument.

Tube Noise Sources I was told generally run out of steam in the few
hundreds of MHz range. Enter the silicon Noise Diode. Noise Diodes can
be purchased that are specified up to 110 GHz. There may be others
out there that can produce noise at higher frequencies. I have never
looked into sources with higher frequency specs as my interests were
much lower in frequency.

The Zener Diodes and some other devices such as the Emitter-Base
Junction of some transistors have been pressed into service as Noise
Generators in the past.  Generally these devices were used to build
one or two sources in a shop and calibrated within the lab. Often they
did not generate a flat amplitude spectrum across the frequency ranges
of interest as well as the Excess Noise Amplitude generated was not
predictable.

Enter the productized Noise Diode. These units are optimized to produce
a specified Excess Noise level across a specified frequency range of interest
with a comparatively flat amplitude response. The HP Noise Heads I have
used in the past have exhibited a Noise Level that was flat within plus or minus
0.5 dB from 1 Mhz to 2 GHz. 

If you look at the specs for the NoiseCom NC302L diode you will notice it
is designed to cover 10 Hertz to 3 GHz. The supply current is specified as
6 mA with an avalanche voltage between 6 and 8 volts. Both the Noise Diode
and the Zener Diode use the avalanche phenomena but the Zener is optimized
for a specific  voltage as compared to the wide voltage spec for the Noise Diode.

Why use a commercially manufactured Noise Diode? Well my lab work
in  the basement at home spans from a few MHz upwards to 2500 MHz.
Being the proverbial tightwad I am not in a mood to hand HP (yeah I
know it is called Agilent now, that is an axe I have to grind with Carley
whatever the heck her name is) $4000.00 plus for a Noise Source knowing
dang well the diode is a $25.00 part with a few chip resistors, connectors
caps and a milled housing all totaling maybe $150.00. (OK I ignored HP's
NRE costs)

Hope the info helps answer some questions.

73

Chuck WD4HXG
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