Roger,
Yes, you are right. As a practical matter, I ran a set of GI7b using the stock
coolers in RTTY service for about 6 months before
moving to some custom coolers which were optimized for lateral cooling. At
that time, I had access to a friends IR analyser which
would produce fantastic and cool pictures.
The hottest spot on the GI7b in severe duty (abuse duty?) is just a bit down
from the anode cap on the ceramic. The fan location
was roughly similar to what Glen has done. That worked out and the temps were
under spec. So for SSB service, which I think is
Glen's focus, this kind of fan arrangement will be really enough even with
serious compression use as long as the idle current is
not cranked up too high.
73, Jeff ACØC
www.ac0c.com
-----Original Message-----
From: Roger (sub1)
Sent: Friday, April 15, 2011 5:40 PM
To: Jeff Blaine
Cc: Glen Zook ; amps@contesting.com
Subject: Re: [Amps] Roller Inductor Choices
On 4/15/2011 3:23 PM, Jeff Blaine wrote:
> Nice looking amp, Glen.
>
> 73, Jeff ACØC
> www.ac0c.com
>
> -----Original Message-----
> From: Glen Zook
> Sent: Friday, April 15, 2011 10:08 AM
> To: amps@contesting.com ; Roger (sub1)
> Subject: Re: [Amps] Roller Inductor Choices
>
> I recently built a 160-meter only amplifier using a pair of GI-7bT tubes. It
> was easy to make a socket for them starting with one
> of the $2.99 aluminum mini-boxes that are sold at Radio Shack. The
> cathode/heater ring connections used stainless steel hose
> clamps
> and the small heater connection used plate caps of the size for 6146 tubes.
>
> There are photos of this socket in the thread at
>
> http://forums.qrz.com/showthread.php?282380-Socket-for-Russian-tubes
>
> Photos of the linear are in the threat at
>
> http://forums.qrz.com/showthread.php?284611-Almost-ready-for-smoke-test!
Very nice looking layout.
One thing I would do differently would be to pressurize the cathode
compartment and build chimneys to direct air up through the anode for
more efficient cooling. But s you are not running the tubes hard I would
think you have sufficient cooling. If plate dissipation is any
indication (and often it's not) a pair of the GI-7Bs should be capable
of about 1200 watts out.
> Glen, K9STH
>
> Website: http://k9sth.com
>
>
> --- On Thu, 4/14/11, Roger (sub1)<sub1@rogerhalstead.com> wrote:
>
> I don't know if the base is the same as the GI-7B but it might be. Check the
> sizes and if they are, there is a guy who makes
> sockets
> for them on e-bay. You can mount them without sockets but they do need air
> for axial cooling...unless you change the cooler to
> one
> that works with transverse cooling.
> _______________________________________________
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>
>
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