[Boatanchors] [ARC5] Making Stable Inductors for 2 MHz

[J. Forster]

Hi Mike,

I've never played w/ a tube VFO, but I know the specs are well within the
art in WW II. Every WW II receiver had what I need in it. I just have
little experience with the design of such coils and was looking for
advice.

I really would rather stay away from a DDS solution, for a number of
reasons, not the least of which is chips going unobtanium. Also, to shape
the envelope correctly requires a bunch of other stuff.

Best,

-John

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




> John -
>
> Regular ham VFOs do better than what you are asking for. About 40 years
> ago
> using a SWAN rig I got a notice of violation that I was about 100 Hz out
> of
> band, while chasing DX. This was on 20 meters, with a tube VFO. You should
> have no problems with your analog solution. If you are really concerned,
> you
> may try a digital solution. Regards -Mike
>
> Mike B. Feher, N4FS
> 89 Arnold Blvd.
> Howell, NJ, 07731
> 732-886-5960
>
> -----Original Message-----
> From: arc5-bounces at mailman.qth.net [mailto:arc5-bounces at mailman.qth.net]
> On
> Behalf Of J. Forster
> Sent: Tuesday, June 28, 2011 9:20 PM
> To: boatanchors at mailman.qth.net; boatanchors at puck.nether.net
> Cc: arc5 at mailman.qth.net; Milsurlus at mailman.qth.net
> Subject: [ARC5] Making Stable Inductors for 2 MHz
>
> Hi All,
>
> I'm working on a LORAN-A simulator for the DAS-1 on the MASSACHUSETTS and
> have a design question.
>
> Background:  LORAN-A transmitted 30-40 uS pulses, carefully times, on
> about 1800 to 2100 KHz. I have the timing =ssues solved.
>
> 'm now looking at building a stable, keyed oscillator in the above
> frequency range. My intention is to use a SS Hartley or Colpitts.
>
> The frequency stability requirement is not great... about +/- 5 KHz, but
> this is larger than can be achieved with ferrite cores I've looked at,
> which are > 0.05% / deg. C.
>
> Any suggestions? I'm thinking of an air core inductor, maybe 1/2" x 1 1/2"
> with roughly 120 T of #30.
>
> Best,
>
> -John
>
> ==============
>
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