[Amps] GU-84B Cooling

Wed Jul 20 07:56:01 EDT 2005

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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