[Amps] GU-84B Cooling
Gary Smith
wa6fgi at sbcglobal.net
Wed Jul 20 10:32:23 EDT 2005
my error, the url is www.towerhobbies.com
Gary
----- Original Message -----
From: Gary Smith
To: PA3DUV ; amps at contesting.com
Sent: Wednesday, July 20, 2005 7:29 AM
Subject: Re: [Amps] GU-84B Cooling
To the list:
In this thread is the mention of IR thermometers. As I fly r/c airplanes, such thermometers for reading cylinder head temps have found their way into my hobby. Raytek is one brand name, it sells for $70.00 or so. Go to www.towerehobbies.com and search for temperature gauge, found one that read +- 2% from -27 to 428 Fahrenheit. Price is $24.95, comes with many features including a "temp hold."
A price such as this beats the dickens of having to pay for a lab grade instrument.
73 to all,
Gary... wa6fgi
----- Original Message -----
From: PA3DUV
To: amps at contesting.com
Sent: Wednesday, July 20, 2005 4:56 AM
Subject: Re: [Amps] GU-84B Cooling
oops.. UV should read IR...
Thanks Rich.
----- Original Message -----
From: <pa3duv at planet.nl>
To: <amps at contesting.com>
Sent: Wednesday, July 20, 2005 1:47 PM
Subject: Re: [Amps] GU-84B Cooling
> Van pa3duv at planet.nl
> Verstuurd op woensdag, juli 20, 2005 11:49 am
> Aan Will Matney <craxd at engineer.com>
> Cc
> Bcc
> 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 at 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 at planet.nl>
>> To: "Will Matney" <craxd at 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 at engineer.com>> To: <amps at 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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>>
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