[GreenKeys] LTSpice

[Ralph Mowery]

----- Original Message ----- 
From: "Jeffrey D Angus" <jdangus at att.net>
To: <greenkeys at mailman.qth.net>
Sent: Sunday, July 21, 2013 1:06 AM
Subject: Re: [GreenKeys] LTSpice


> On 7/19/2013 12:11 PM, John Nagle wrote:
>> That's good to know.  I've been using 1uf and 100 ohms.  Same
>> R/C ratio.  Note that you need at least 500V ceramics for that
>> snubber; there's a big voltage spike when the selector magnets
>> dump.
> The same ratio perhaps, but way different results.
>
> Similar to the 100 nF and 470 ohm combination, this has considerable
> ringing. And the overshoot. Oh my.... It peaks at 276 volts. 156v (130% )
> above the nominal 120 v supply.
>
> This is why I ended up with 470 nF (0.47 uF) and 470 ohms.
> I'm using yellow Mylar caps rated at 630 vdc.
>
> With .47 uF and 470 ohms, I get a peak of 144 vdc. Only 24 v (20%) above
> the nominal 120 v supply. And only one basic ring.
>
> Jef-1.0
> wa6fwi
>

I often look over old magazine articals just for general information.  I saw 
an artical the other day about marking and spacing bias of the rtty signals.

In it was a mention of the snubbing circuit and that it would contribuit to 
the marking bias. It did not mention anything about how much or what values 
to use.  Just very little info on that part of the circuit.

I just wonder that while adjusting the values to solve one problem if maybe 
another problem might be created ?

I don't know enough about computer simulations to say if it is possiable to 
look at how much distortion may be caused by differant values of the 
snubbing circuit or if is even enough to worry about.