[Milsurplus] Making Stable Inductors for 2 MHz

[J. Forster]

> John,
>
> You can make a fairly stable FET based LC oscillator but if you key the
> oscillator the ocsillator may vary in frequency or "chirp" when turning
> on. The LC oscillators in Ham rigs prevented this letting the oscillator
> free run and keying a buffer stage. I'd recommend letting the oscillator
> free run, key the buffer stage and shape the signal at the buffer.

This approach makes shaping the pulse harder. I'd prefer a keyed
oscillator. Some chirp will not matter at all.

> Does the oscillator have to be tuneable or fixed frequency? If it's fixed
> frequency I'd use a crystal/divider circuit with a keyed buffer stage.

I could use crystals, but IMO they are not needed for the four frequencies
I need. I only need +/- 5 KHz / 2 MHz.

> It would be interesting to find out how Loran Receiver's were bench
> tested. Does andyone have nany information on Loran test sets?

I have an original TS-251. It is tube from 1944 and generates the correct
RF pulse...  with a keyed oscillator and RLC filter. And it works just
fine.

The problem is that the pulse timing is designed for testing, not
simulated operation. A real simulator requires more complex timing which
I'll eventually do with a uC or uP.

What I'm trying to do is build the output stage first, and use Tektronix
DD501's ans a PG501A to do the timing.

Best,

-John

==============
>
> 73.
>
> Mike N2MS
>
>
>
>
> ----- Original Message -----
> From: J. Forster <jfor at quik.com>
> To: Milsurplus at mailman.qth.net
> Sent: Wed, 29 Jun 2011 01:24:20 -0000 (UTC)
> Subject: [Milsurplus] 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.
>
> <snip>