[Milsurplus] 991 neon lamp

[J. Forster]

For those intetrested in relatively current Noise measurement, there is an
AILtech Group on Yahoo.

However noisy, I'd still like a couple of NE-16 / 991s for my ARB.

-John

===============

> Of course I can see how that may well be true, as gaseous tubes have been
> used as broadband noise sources for years, especially the fluorescent
> types.
> Still, their ENR is doubtfully great enough to overcome a WWII front end
> NF
> and even the atmospheric noise prevalent there. Of course, zeners have
> been
> used as noise sources as well and the choice for state of the art noise
> sources is a solid state diode. Heck, even a tube filament or a light
> bulb,
> generates considerable ENR above kT (where T=290K). In the 70's there was
> an
> article in "Ham Radio" magazine as to how to make a noise source from an
> incandescent light bulb. I built that circuit and used it to measure the
> NF
> of some of my UHF preamps. I personally have not experienced a noise
> problem
> by the 991s in the 348s that I used in the past. I suppose this is not
> really OT in this forum. 73 - Mike
>
> Mike B. Feher, N4FS
> 89 Arnold Blvd.
> Howell, NJ, 07731
> 732-886-5960
>
>
>
> -----Original Message-----
> From: milsurplus-bounces at mailman.qth.net
> [mailto:milsurplus-bounces at mailman.qth.net] On Behalf Of Richard Brunner
> Sent: Saturday, January 16, 2010 11:16 AM
> To: milsurplus
> Subject: Re: [Milsurplus] 991 neon lamp
>
> The 991 neon lamp is actually a voltage regulator rated 55 to 60 volts
> at 2 ma, with 87 volts striking voltage.  They recommend changing at
> 1000 hours.  My experience is they drift up in operating voltage with
> use and time.  Ones I have tested regulated between 80 to over 100
> volts.  I doubt an old one can be found in as-new condition, and would
> use a Zener.  I also read that in the BC-348 receiver the 991 is a noise
> source, and receiver performance improves when it is removed.
>
> Richard, AA1P
>
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