Hi Chris,
You are quite correct. I took a closer look at my L-7 last night, and indeed
the fan
is sucking air out rather than blowing it in. When I first looked at it, I
guess I just
assumed the air was moving the other way. Also, it looks like the only openings
in
the L-7 chassis, are the fan outlet on the back and the air inlet on the bottom
under
the tube sockets. So indeed, the L-7 chassis is pressurized (negative gauge
pressure
in this case), whereas the chassis on the SB-220, if memory serves correct, is
not (I
believe the case on the Heath is made with perforated sheet metal).
Still seems like the L-4B air system would be more effective with the glass
chimneys
and the blower, but I can't say for sure as I have never done any of the
calculations.
Another exercise for the student (me) I guess.
73 de Mike, W4EF........................................
is made with ----- Original Message -----
From: "Chris Pedder" <g3vbl@netcomuk.co.uk>
To: "Michael Tope" <W4EF@dellroy.com>
Sent: Thursday, May 24, 2001 10:55 AM
Subject: Re: [AMPS] This guy is gotta be kidding!
> At 21:31 23/05/2001 -0700, you wrote:
>
> >Chuck,
> >
> >Also notice the cooling. The L4B uses a squirrel cage blower to
> >pressurize the chassis and force air up thru the tube sockets to
> >a set of glass chimneys. The L-7 uses a muffin blowing air
> >horizontally across the glass bottles as is done in the Heathkit
> >SB-220.
> >
> >Mike, W4EF...............
> Mike,
>
> I'm not at home with my L7 but I don't think this is entirely true.
> Although I think the L7 cooling is less good than the L4B, it's not quite
> as you describe/imply. The air is drawn past the tube pins and through the
> socket before being exhausted through the fan at the back.
>
> Love my L7 and wouldn't mind getting hold of an L4B but they are not too
> common in U.K.
>
> Best wishes,
>
> Chris
>
--
FAQ on WWW: http://www.contesting.com/FAQ/amps
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
|