[R-390] Thermistor info for soft start?

[Barry]

I've used a CL-80 as well.

Barry - N4BUQ

----- Original Message -----
From: "Tim Shoppa" <shoppa_r390a at trailing-edge.com>
To: <r390a at bellsouth.net>; <r-390 at mailman.qth.net>
Sent: Wednesday, February 01, 2006 6:42 PM
Subject: Re: [R-390] Thermistor info for soft start?


> Tom Norris <r390a at bellsouth.net> wrote:
> > What is the spec of the thermistor needed for the 390 and 390A to
> > give it soft start?  I had ordered a couple of the Keystone things
> > from Digi-Key several years ago, but am going to place a Mouser order
> > the next day or so and would like to get a couple from them for the
> > "new" stuff that just came in.
>
> The one I use is a CL-80. Rated at a max current of 3 Amps (and a
> R-390A with ovens off is about 1.5 Amps, with ovens on is a little
> over 2 Amps) and cold resistance of 47 ohms.
>
> I don't know the official spec for max current of a R-390 but I'm
> guessing it's similar or maybe just a little more.
>
> Other ones with a similar max current rating will work too. As you go up
> in max current rating, the cold resistance will drop and the current
> limiting effect will go down. If you go too low in max current rating you
> risk burning up something.
>
> The CL-80 gets rather warm in operation - which means it is doing its job.
> In my radio it gets to the point where it would be uncomfortable for me
> to touch it more than just momentarily. And of course it is wired in the
> hot AC lead so you gotta be careful not to touch the leads! Teflon is a
good
> thing for covering the leads.
>
> Wow, if you need a couple does that mean you just acquired a couple
> more 390/390A's? I'm jealous :-).
>
> Mouser part # 527-CL80.  Digikey part # KC008L-ND. Can't believe I just
> spent 4 or 5 whole paragraphs characterizing a single part!
>
> Tim.
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