FW: [Test-Equipment-For-Sale-Wanted-or-Exchange] Looking for low ENR noise source
Lester Veenstra
Lester B Veenstra K1YCM MØYCM W8YCM 6Y6Y W8YCM/6Y 6Y8LV (Reformed USNSG CTM1)
452 Stable Ln
Keyser WV 26726 USA
GPS: 39.336826 N 78.982287 W (Google)
GPS: 39.33682 N 78.9823741 W (GPSDO)
Telephones:
Home: +1-304-289-6057
US cell +1-304-790-9192
Jamaica cell: +1-876-456-8898
From: ma...@Test-Equipment-For-Sale-Wanted-or-Exchange.groups.io [mailto:ma...@Test-Equipment-For-Sale-Wanted-or-Exchange.groups.io] On Behalf Of Lester Veenstra via groups.io
Sent: Monday, June 10, 2024 10:49 AM
To: ma...@Test-Equipment-For-Sale-Wanted-or-Exchange.groups.io
Subject: Re: [Test-Equipment-For-Sale-Wanted-or-Exchange] Looking for low ENR noise source
I have had good results with: RF-Gadgets I believe he even offers to run your unit through his Calibration to generate a new table.
https://www.ebay.com/itm/156242485508
Lester B Veenstra K1YCM MØYCM W8YCM 6Y6Y W8YCM/6Y 6Y8LV (Reformed USNSG CTM1)
452 Stable Ln
Keyser WV 26726 USA
GPS: 39.336826 N 78.982287 W (Google)
GPS: 39.33682 N 78.9823741 W (GPSDO)
Telephones:
Home: +1-304-289-6057
US cell +1-304-790-9192
Jamaica cell: +1-876-456-8898
From: ma...@Test-Equipment-For-Sale-Wanted-or-Exchange.groups.io [mailto:ma...@Test-Equipment-For-Sale-Wanted-or-Exchange.groups.io] On Behalf Of Jeff Kruth via groups.io
Sent: Monday, June 10, 2024 9:52 AM
To: ma...@Test-Equipment-For-Sale-Wanted-or-Exchange.groups.io
Subject: [Test-Equipment-For-Sale-Wanted-or-Exchange] Looking for low ENR noise source
Every few years this comes up, questions about noise sources. Pretty much ALL noise sources (I hate to say all, as there will some exception that will be brought up) are very high ENR noise diodes (not talking gas here!). And a precision attenuator is fitted to reduce the value. Most are 35 dB as built (IIRC, HP did not make their own diodes,but back in my day bought sources from MSC and incorporated them in the HP housing with the appropriate attenuator). I think the noise line of Microwave Semiconductor was bought by Micronetics (I cant keep track of who bought who these days, I have been at this for 50 years).
Now to say that a Low ENR source as purchased is better than a higher one with an attenuator is foolish, provide that none of the associated components is faulty, they all begin life as a high ENR diode in a small box then are padded to the desired level. It has never been told to me by any diode vendor that you can make the raw diodes any value you want! They all start off the same ENR value (+,-) and the attenuators are selected to the desired value. My assumption, probably correct, is that the diode makers found the secret sauce for a given ENR value, make only these, and then pad the answer. You can order and purchase any value of ENR from 35 dB to 1 dB, depending on what your system requirements are.Not all sources are used for benchtop measurement, some are system verification testing and are built in to reciever systems with injection couplers.
Therefore, if you use a precision, undamaged attenuator with a calibrated (via AVNA) value, and you know the values for the source, (and if really fussy, apply a little math), you get the same result. And remember, load and source VSWR will affect the result, right? As noted previously "hot/cold" variation may be significant and the pad reduces this.
Jeff Kruth
WA3ZKR
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