No cooling fan Warren just open "ish" air circulation without it things
got a little warm especially at 100F ambient in the summer....I love Okie...
>From: [email protected] (Warren K2ORS/WD2XGJ)
>Reply-To: [email protected]
>To: [email protected]
>Subject: Re: LF: Re: Keeping the smoke in
>Date: Thu, 02 Feb 2006 23:10:18 +0000
>
>Hi Mike,
>
> I don't think that the cores were damaged from the last incident. I was
>able to run the 250 watt transmitter through it with no problem and no
>measureable reflected power. I understand that Laurence also used 3 stacked
>FT-290-77s but actively cooled it. A cooling fan is not easy to do in my
>case since the tuner is in a weathertight box.
>
>--
>73 Warren K2ORS/WD2XGJ
>FN42hi
>http://www.w4dex.com/wd2xgj.htm
>
> -------------- Original message ----------------------
>From: "MIKE REID" <[email protected]>
> > What cores did Laurence use and what wire size & type? Sorry to hear she
>failed
> > again. Maybe the cores got damaged the other day with no external
>indications
> > like cracking or? I don't recall you having trouble with the transformer
>when it
> > was dry and Teflon is way better than cotton so that leads me to think
>the cores
> > were no good after the first heat cycle/failure.
> >
> > Mike
> > WE0H
> >
> > ----- Original Message -----
> > From: Warren K2ORS/WD2XGJ
> > To: rsgb lf reflector<mailto:[email protected]>
> > Cc: LWCA LF Reflector<mailto:[email protected]>
> > Sent: Thursday, February 02, 2006 4:41 PM
> > Subject: LF: Keeping the smoke in
> >
> >
> > Hello the list,
> >
> > I've heard that the secret to keeping things going in
>electronics is to
> > make sure you don't let the smoke out (that's what makes it all work
> > apparently).
> >
> > I have again failed to do so. After rewinding my toroidal loop
> > transformer in the ATU, I had a core overheating problem. The core is 3
>stacked
> > FT-290-77 ferrites.
> > After setting the Decca up on QRSS for an hour or so I noticed a
>problem with
> > the rf output current, it was pulsing up and down as if the Decca guard
>circuit
> > was cutting in to protect the PA. So I through the breaker and went out
>and
> > opened the tuner box. Smoke poured out. Bad news. I checked the
>temperatures
> > with a non-contact infra-red thermometer and the toroid core was 343
>Farenheit.
> > The Curie temperature for type 77 ferrite is 200 C (which is 392
>Farenheit).
> > Not sure yet if the core is permanently damaged, I'm still waiting for
>it to
> > cool down.
> >
> > All credit to Laurence who managed to get a loop to work at this
>power
> > level! And especially with the currents he dealt with in the parallel
>wire loop
> > configuration.
> >
> > I guess I need a bigger core than the 3 stacked FT-290-77s any
>suggestions
> > out there?
> >
> > --
> > 73 Warren K2ORS/WD2XGJ
> > FN42hi
> > http://www.w4dex.com/wd2xgj.htm<http://www.w4dex.com/wd2xgj.htm>
> >
> >
>
>
>
>From: "MIKE REID" <[email protected]>
>To: <[email protected]>
>Subject: LF: Re: Keeping the smoke in
>Date: Thu, 2 Feb 2006 22:50:50 +0000
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