Van pa3duv@planet.nl
Verstuurd op woensdag, juli 20, 2005 11:49 am
Aan Will Matney <craxd@engineer.com>
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Onderwerp Re: [Amps] GU-84B Cooling
Will,
Perhaps I could measure the anode cooler temperature with a UV
thermometer.
"Contesting conditions" is a rather vague performance indicator, I
could run the amplifier flat out full carrier for a defined period of
time and then measure the cooler temperature afterwards.
I will set up a measurement session, measuring the pressure in the sub
chassis in mm-H2O and the temperature in degrees Celcius. It is very
difficult to measure the actual airflow without proper anemometers and
a measurement-tube.
The B+ current is approx. 3.5 amps @ 6000 watt output. The power gain
is approx 20 dB and the output power is adequate. The 3-phase B+
transformer is switched in a delta configuration, AC voltage between
the phases is approx 390 VAC @ 50 Hz. The airflow noise is of no
concern to me since I always use a headset. I'll get back with some
more detailed measurements later on.
Cheers, Dick Knol
PA3DUV
----- Oorspronkelijk bericht -----
Van: Will Matney <craxd@engineer.com>
Datum: woensdag, juli 20, 2005 10:12 am
Onderwerp: Re: [Amps] GU-84B Cooling
> Dick,
>
> I'm not saying it's a bad tube, and dont want none to think that.
> I just dont want anyone to undercool the tube so it will last. Who
> knows, the 4CX1500 may have an over-sized radiator too! About the
> only way to tell about the temp would be to use a thermocouple
> connected to the anode. Then the temp read under contesting
> conditions both under SSB and AM using the air flow they
> recommend. AM/CW creates a good bit more load on one as does SSB
> transmissions. Then if the temp stays down where it should, one
> would know it would be ok. I'm like Rich, and what George
> mentioned, use the largest blower possible. Another thing too is
> maybe mount and external blower and duct it to the amp. You can
> set one of these in another room to help kill the sound down if
> it's a concern. On yours, you may have the right combination by
> using enough fans both pushing and pulling. Have you measured what
> the air flow and pressure is on your amp? If so, let us know so we
> all have a starting point.
>
> Best,
>
> Will
>
> ----- Original Message -----
> From: PA3DUV <pa3duv@planet.nl>
> To: "Will Matney" <craxd@engineer.com>
> Subject: Re: [Amps] GU-84B Cooling
> Date: Tue, 19 Jul 2005 22:45:03 +0200
>
> >
> > Will,
> > In my twin tube GU84B amp one fan is used to pressurize the
> > subchassis and two axial fans to draw the air out.
> > With a B+ of 2900 VDC, from the 3 phase PSU the two GU84B tubes
> > generate an easy 6 kW of output. During normal (6 dB compressed)
> > SSB transmissions the exaust air stays below 55 degrees celcius.
> > Cheers, Dick Knol
> > PA3DUV
> >
> >
> >
> > ----- Original Message ----- From: "Will Matney"
> <craxd@engineer.com>> To: <amps@contesting.com>
> > Sent: Tuesday, July 19, 2005 9:53 PM
> > Subject: [Amps] GU-84B Cooling
> >
> >
> > > On a webpage somewhere, I cant remember now where, I read
> about
> > > the GU-84B (4CX1600) having an undersized radiator. I think it
> > > was on a Russian amateur website. What I had read was this
> tube
> > > was actually designed for running in a missle by the Russians,
> > > and was designed for a 1 time use. So, they undersized the
> > > radiator a good bit because of space limitations. They were
> > > making the comparison to a 4CX1500's radiator size being
> larger
> > > in the discussion. However the guts of the GU-84B supposed to
> be
> > > really good. So this brings the delima of how to cool it so
> one
> > > would get a long life out of it. One way would be add some
> sort
> > > of extra aluminum heat fins, or some made of brass, with fins
> > > sticking out to catch more air, thus increasing the overall
> > > surface area. The only other way would be to increase the
> amount
> > > of air flow and volume over the fins that's there. When doing
> > > this though, the noise goes up from the blower. However, if
> one
> > > is going to dealve into using the GU-84B, I'd s
> > > uggest looking into this and compare the sizes between its
> > > radiator and the one for the 4CX1500. Even though the tube is
> > > cheaper than some others, it's still expensive if you have to
> > > re-tube all the time. If I can remember where I seen this,
> I'll
> > > post the link.
> > >
> > > Best,
> > >
> > > Will
> > >
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