[Milsurplus] 991 neon lamp

[J. Forster]

Hi Mike,

Thanks very much. It's very kind of you.

I'll send you my mailing address-off list.

Best,

-John

==========

> John -
>
> I went downstairs into the dungeon and low and behold, in spite of the
> flood, I found the box where I thought some 991s may lurk. I grabbed 4 of
> them and tested just two. Those two both worked fine. One is made by Kuthe
> Labs and the other by RCA. The KL one struck at about 84 volts and
> regulated
> at 65 volts through a 20K limiting resistor. The RCA struck at about 75
> volts and regulated at 55 volts through the same resistor. You are welcome
> to either, but, I expect you would prefer the RCA. Send me your address
> and
> I'll have it in Tuesday's mail. - 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 J. Forster
> Sent: Saturday, January 16, 2010 1:09 PM
> To: 'milsurplus'
> Subject: Re: [Milsurplus] 991 neon lamp
>
> 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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>
>
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