Although both distilled and deionized (DI) water have an affinity for
copper and other metals, I'd not expect that to be much of a problem
with the intermittent service at an amateur station. For good measure a
small vinyl tank (5 or 10 gallons) could be used as a holding tank with
the metal parts only receiving water when running. Use a buffer tank
(one or two quarts) so with a pump failure the tube will have that
reserve for protection.
Likewise I'd stay away from soft solder connections like a radiator, but
at amateur power levels it doesn't take a lot of water for efficient and
sufficient cooling. However it does depend on the area of heat transfer
from the anode to water. As a wild guess, I think it'd probably take
between a pint and a quart per minute for a legal limit amp, or even one
of the contest monsters.
In another conversation the subject of water hose length came up. For
those using anode water cooling how long a piece of tubing do you use
for safety and isolation between the plate and ground, or where leaving
the enclosure? It's been over 20 years since I worked with this stuff
and "as I recall" we used between 15 and 20 feet of coiled hose from the
anode running 6 Kv DC. IIRC it wasn't a lot more even in the big RF
generators. I don't think we ran over 8 or 10 Kv DC on anything.
73
Roger (K8RI)
Carl wrote:
> I would think that a cooling or heater core with soldered assembly would
> create problems with the water purity pretty fast? Cant have anything in the
> water to promote conductivity. Maybe a micro rice box plastic radiator
> would work.
>
> Carl
> KM1H
>
>
> ----- Original Message -----
> From: "Randall, Randy" <Randy.Randall@healthall.com>
> To: "'Carl'" <km1h@jeremy.mv.com>; <jtml@vla.com>; <amps@contesting.com>
> Sent: Friday, December 18, 2009 11:24 AM
> Subject: RE: [Amps] water cooling
>
>
> Are you going to use a pump or go the thermosyphon route? If the later the
> pipe on the transmission cooler is too small. My old '48 International
> Harvester Cub uses the thermosyphon system to cool the 18-20 HP engine. A
> small car radiator would work OK and you would not need a pump or fan.
>
> Randy AB9GO
>
> -----Original Message-----
> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
> Behalf Of Carl
> Sent: Friday, December 18, 2009 9:54 AM
> To: jtml@vla.com; amps@contesting.com
> Subject: Re: [Amps] water cooling
>
> I dont have any cooling specs on the tube, it is a 60's era Amperex which is
> probably a Phillips or other Euro design. The tube doesnt have a water
> jacket; I'll have to make one.
>
> No, I dont want vapor, just water and the condensor would be fan cooled. Im
> thinking of using an automotive external transmission cooler as a starting
> point.
>
> Carl
> KM1H
>
>
>
> ----- Original Message -----
> From: "John Lyles" <jtml@losalamos.com>
> To: <amps@contesting.com>
> Sent: Thursday, December 17, 2009 10:09 PM
> Subject: [Amps] water cooling
>
>
>
>> I would recommend to check into the datasheet for flow volume versus
>> dissipation, if it is a well-spec'd tube. As for size of condensor, you
>> are talking vapor cooling I guess. One good source of info is to find an
>> older Thomson tube catalog, when they described their vapotron cooling
>> technique in the 1970s. Then they had Supervaporton. Once they went to
>> Hypervapotron, it got a lot more complicated in some ways, simpler in
>> others. For instance, no need for a condensor at all. But water purity and
>> oxygen level, plus the type of plumbing used, became very important. This
>> is similar to CPI's multiphase cooling, where the phase changes from steam
>> to water in the water jacket of the anode.
>>
>> I have been using a pair of 4CW250,000B tetrodes all week as a pulsed 200
>> amp power load. No RF, just DC driven with a pulse generator. They are
>> loading my plate power supply for testing, before I finish the RF
>> amplifier that will be drawing that current next spring. The power supply
>> and capacitor bank (250 uF) must function well together before i stick a
>> very expensive cavity amplifier on the end of the cable.
>>
>> Each Eimac tetrode has 40 GPM flowing, water is about 1 Megohm-cm
>> resistivity, to allow no more than a mA or so of current in each 9 foot
>> long 1.5 inch ID water hose. The real amplifier will need 130 GPM in the
>> anode, and 5 other water loops of < 1 GPM for filament, screen, and
>> cavity. When water cooling shoot for keeping the temp rise across the
>> anode at about 5 - 10 deg C or less, and keep the flow reasonable for the
>> pipe size, using standard pipe calculations. Too much flow will erode
>> fittings. Too high a resistivity will strip ions from fittings and cause
>> metal to move around and get plated in places you'd rather not (like
>> inside of anode or hose fittings). For hoses, design them as a cylindrical
>> resistor of water, and figure out the ohms per cm or meter, and then just
>> make them long enough to keep leakage small, under a mA if possible. Use
>> rubber, or polymer hoses or even PVC pipe, nothing with a lot of dark
>> carbon (black hose). RCA use to say something like 4 Meg ohm pe
>> r kV of
>> plate voltage I believe.
>>
>> Happy Holidays
>> John
>> K5PRO
>>
>>
>>> Id like to test a Class C industrial tube (Not on a ham band!) Ive had
>>> for
>>> almost 25 years when I stripped the self excited oscillator for parts.
>>> The
>>> questions would be how to calculate the necessary flow volume based on
>>> plate
>>> dissipation, size of condensor, suitable hosing, controls, sensors, and
>>> all
>>> that good stuff.
>>>
>>> Carl
>>> KM1H
>>>
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>> http://lists.contesting.com/mailman/listinfo/amps
>>
>
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