Ive had several 3CX800 amps come thru for service that have had blower
failure and the tubes actually melted the Eimac chimneys.....and survived!
Its a pretty rugged tube.
Carl
KM1H
----- Original Message -----
From: <TexasRF@aol.com>
To: <keepwalking188@yahoo.com>; <amps@contesting.com>
Sent: Monday, November 08, 2010 7:06 AM
Subject: Re: [Amps] time to death in the event of a blower failure
> Hi Jeff, that sounds like a really nifty device. Personally, I like the
> idea of having an air flow switch and your heat sensor. Easy for me to say
> huh?
>
> It seems that the air flow sensor could be set for the lowest blower
> speed
> to be covered for all higher speeds. I have not worked with one so
> perhaps
> there are unfamiliar issues here.
>
> It does seem reasonable that the heat sensor could be set slightly above
> the normal air exhaust temperature at the lowest blower setting and
> provide
> the protection you want. Knowing that heat tends to rise and that you
> would
> never run the tube that close to meltdown makes one think there would be
> ample time to sense a failure act on it.
>
> You can do a lot of controlled testing by lowering or removing the
> operating bias to let the tube plate current increase the standing
> dissipation and
> heat.
>
> Please do let us know your results.
>
> 73,
> Gerald K5GW
>
>
>
>
>
> In a message dated 11/7/2010 10:27:58 P.M. Central Standard Time,
> keepwalking188@yahoo.com writes:
>
> The traditional monitor for a failed blower is a air pressure sensor.
> But
> this is harder to implement with a variable speed fan arrangement.
>
> I was working on a fail-safe for this case and thought a solution.
> Wanted
> to run that idea by the board to see what the comments are...
>
> Here’s the idea...
>
> 1. The cut-out mechanism would be one of these TO220 sized bimetal
> switches. They are available in a variety of trip points.
>
> 2. The switch has no electronics inside and should be RF immune.
>
> 3. The switch can be set in the chimney near the silicon wall and would
> not significantly impede airflow.
>
> 4. The switch has a very low thermal mass and will switch quickly.
>
> 5. Even with a failed blower, the tube would be dissipating tons of heat
> and convection would ensure heat-up of the switch.
>
> 73, Jeff ACØC
> www.ac0c.com
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|