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LDMOS for QRO

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Brendan Minish

Re: LDMOS for QRO [OT]

What might be even more interesting is mineral oil immersion cooling.
You would still need a heatsink to conduct heat away from the PA
device(s) but the advantage to oil immersion cooling is that it can also
efficiently cool all the other parts such as Low pass filter coils,
Voltage regulators, power supply etc.

It's becoming a thing in High performance computing for servers
http://www.datacenterknowledge.com/archives/2012/09/04/intel-explores-mineral-oil-cooling/

I guess one of the questions at RF is how much the dielectric constant
of the oil will change things and if it's enough that it needs to be
taken into account at the design phase.

For our application the thermal mass of the oil combined with our duty
cycles would also help keep the radiator requirements reasonable

I love the idea of having a silent High power Amplifier.

On Tue, 2014-12-16 at 12:06 -0700, Doug Person via Elecraft wrote:

> This is really a fascinating idea. I have noticed that there are water
> cooling kits made for computer CPU's. Some of the bigger CPU's run over
> 225 watts of power. I wonder how applicable one those CPU kits might
> be. They include a heat sink, pump and radiator.
> 73, Doug -- K0DXV
>
> On 12/16/2014 11:10 AM, David Cutter wrote:
> > Hi Dick
> >
> > Start from the LDMOS data sheet and work out the temperature you wish
> > to keep within at the junction. Because water cooling is so good, you
> > can choose either to run the device cooler than you would with air
> > cooling to improve reliability, or stick to the same temperature and
> > get more power / use a smaller cooling plate / use less water. There's
> > a direct relationship between reliability and temperature, but it's
> > not linear. Then use the temperature rise per W rating of the device
> > to get to the surface temperature.
> >
> > In work I did >10 years ago all devices were directly bolted to the
> > liquid-cooled plate without an intermediate spreader, however, these
> > LDMOS devices are so small (ie very high heat density) there is a good
> > reason to spread the heat out first before cooling proper takes place,
> > I'm somewhat hazy what thickness, but you must achieve good flatness
> > of contact against the plate. Some very large devices eg IGBTs and
> > rectifiers the size of your open hand are supplied curved and the
> > bolting-down process achieves the flatness with the correct torque
> > setting on the bolts.
> > Then you do the same sums as you do with air cooling ie temperature
> > rise v watts dissipated from the heat sink data.
> >
> > Say you want to dissipate 1kW of heat continuously (eg in a data
> > contest) then a small 2 pass model would give you around 90 to 100K
> > rise at the surface of the plate with 1 US gallon per minute, whereas
> > a 4 pass model would give you around 20K rise on a 152mm length plate.
> > This of course assumes that the heat is being delivered into the plate
> > evenly over the whole surface, ie using a spreader. Heat sink paste
> > adds a little to the thermal gradient and is needed in very small
> > amounts, evenly spread.
> >
> > Do the sums several times with different criteria until you get to the
> > one you feel comfortable with. If you live in a cold climate you can
> > dump the heat into a small central heating radiator to keep the shack
> > warm and no fans required just an aquarian pump to run it; if you live
> > in a hot place, then put the radiator on the shade side of the house
> > or even bury it. If water is abundant, eg river water or a pond, you
> > can re-cycle it back to the source.
> >
> > You can make your own water cooling plate, see here a small example
> > cooling a dozen TO-220 devices:
> > https://www.youtube.com/watch?v=WGpau-raMho
> > Somebody here will check my sums I'm sure.
> > 73
> > David
> > G3UNA
> >
> > ----- Original Message ----- From: "Richard Solomon"
> > <[hidden email]>
> > To: <[hidden email]>
> > Sent: Tuesday, December 16, 2014 4:44 PM
> > Subject: Re: [Elecraft] LDMOS for QRO [OT]
> >
> >
> >> If one wanted to use one of these to cool an LDMOS VHF KW, where would
> >> one find the design info to calculate which cold plate would provide
> >> sufficient
> >> cooling ?
> >>
> >> I envision a stack something like this:
> >>
> >> LDMOS PC Board
> >> Copper Heatsink (thickness need be determined)
> >> Cold Plate
> >> Aluminum Heat Sink (is this really necessary ?).
> >>
> >> 73 es HH, Dick, W1KSZ
> >>
> >>
> >> On 12/14/2014 4:32 PM, David Cutter wrote:
> >>> I'm a little surprised that folks in this group haven't suggested
> >>> liquid cooling for this modest application. Semiconductor cold
> >>> plates have been around for a long time, are economical to use and
> >>> in my view a much better solution than forced air cooling. They are
> >>> compact, quiet, require far less cabinet space, keep junctions
> >>> cooler and more stable than air could ever and enable higher
> >>> reliability.
> >>>
> >>> Look at Aavid for instance, whose devices I used on many occasions:
> >>> http://www.aavid.com/sites/default/files/products/liquid/pdf/liquid-cold-plate-datasheet-hicontact.pdf
> >>>
> >>>
> >>> If you play your cards right, you can cool the amplifier and the
> >>> power supply on a short 4-pass plate. Put the heat somewhere
> >>> convenient, not in your shack.
> >>>
> >>> 73
> >>>
> >>> David
> >>> G3UNA
> >>>
> >
> > ______________________________________________________________
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> >
>
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--
73
Brendan EI6IZ

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Wes (N7WS)

Re: LDMOS for QRO [OT]

In reply to this post by Wes (N7WS)

Oops typo. "F-14" aircraft

On 12/16/2014 10:27 AM, Wes (N7WS) wrote:

> Unless you want to run fresh water down the drain (in Arizona we don't do
> this) you have to get the heat into the air someplace. I'm not sure that
> running water lines to outside air is much easier than getting coax through a
> concrete wall.
>
> Speaking of difficult, the U.S. Navy AIM-54A Phoenix Missile which with I was
> intimately familiar, used oil (Coolanol) cooling. Chassis were mounted on cold
> plates and the vacuum tube modulator and pulse transformer were immersed in
> oil and it also circulated through the PA klystron. Lines ran from the
> missile umbilical to the wing or belly mounted launchers then to the F4
> aircraft where a conditioning unit resided. The stuff was insidious to work
> with. I ruined lots of clothes, And it was hygroscopic, just the thing to
> use on a ship-borne system.
>

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Bill Steffey NY9H

Re: loading firmware oops

In reply to this post by Wes (N7WS)

oops...

tried to load new fw and it got confused.

Now when i try to force load,
i can not get the utility to give me a
" send" screen...either one ...all or selected...

and the led keeps blinking and "mcu ld" stays on the k3 lcd;

even changed computers to get a simple hw serial port

which is set to 38.4k

what did I forget ?????
bill

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Dick Dievendorff-4

Re: loading firmware oops

In reply to this post by Wes (N7WS)

K3 Utility Help, Troubleshooting, MCU Load Failure, has a step by step procedure for interrupted firmware loads.

73 de Dick, K6KR

> On Dec 17, 2014, at 18:00, Bill NY9H <[hidden email]> wrote:
>
> oops...
>
> tried to load new fw and it got confused.
>
> Now when i try to force load,
> i can not get the utility to give me a
> " send" screen...either one ...all or selected...
>
> and the led keeps blinking and "mcu ld" stays on the k3 lcd;
>
> even changed computers to get a simple hw serial port
>
> which is set to 38.4k
>
> what did I forget ?????
> bill
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html
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Bill Steffey NY9H

Re: loading firmware oops

just got it going,,,

now i will read that.... while it loads

tnx

At 09:12 PM 12/17/2014, you wrote:

>K3 Utility Help, Troubleshooting, MCU Load Failure, has a step by
>step procedure for interrupted firmware loads.
>
>73 de Dick, K6KR
>
> > On Dec 17, 2014, at 18:00, Bill NY9H <[hidden email]> wrote:
> >
> > oops...
> >
> > tried to load new fw and it got confused.
> >
> > Now when i try to force load,
> > i can not get the utility to give me a
> > " send" screen...either one ...all or selected...
> >
> > and the led keeps blinking and "mcu ld" stays on the k3 lcd;
> >
> > even changed computers to get a simple hw serial port
> >
> > which is set to 38.4k
> >
> > what did I forget ?????
> > bill
> > ______________________________________________________________
> > Elecraft mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:[hidden email]
> >
> > This list hosted by: http://www.qsl.net
> > Please help support this email list: http://www.qsl.net/donate.html
> > Message delivered to [hidden email]

Rick WA6NHC

Re: loading firmware oops

In reply to this post by Dick Dievendorff-4

And sometimes, you have to reboot the computer because the (USB to) serial driver goes wonky and that's the simplest recovery.

Yes saw you changed computers; just submitting it for completeness.

73 es Merry Christmas,
Rick wa6nhc

Tiny iPhone 5 keypad, typos are inevitable

> On Dec 17, 2014, at 6:17 PM, Bill NY9H <[hidden email]> wrote:
>
> just got it going,,,
>
> now i will read that.... while it loads
>
> tnx
>
> At 09:12 PM 12/17/2014, you wrote:
>> K3 Utility Help, Troubleshooting, MCU Load Failure, has a step by step procedure for interrupted firmware loads.
>>
>> 73 de Dick, K6KR
>>
>> > On Dec 17, 2014, at 18:00, Bill NY9H <[hidden email]> wrote:
>> >
>> > oops...
>> >
>> > tried to load new fw and it got confused.
>> >
>> > Now when i try to force load,
>> > i can not get the utility to give me a
>> > " send" screen...either one ...all or selected...
>> >
>> > and the led keeps blinking and "mcu ld" stays on the k3 lcd;
>> >
>> > even changed computers to get a simple hw serial port
>> >
>> > which is set to 38.4k
>> >
>> > what did I forget ?????
>> > bill
>> > ______________________________________________________________
>> > Elecraft mailing list
>> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> > Help: http://mailman.qth.net/mmfaq.htm
>> > Post: mailto:[hidden email]
>> >
>> > This list hosted by: http://www.qsl.net
>> > Please help support this email list: http://www.qsl.net/donate.html
>> > Message delivered to [hidden email]
>
> ______________________________________________________________
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>
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Bill Steffey NY9H

Re: loading firmware oops

the trick was to wait much more than I had ,.,,,

i use hardware serial ports,,,in the computer

tnx all

bill

At 09:36 PM 12/17/2014, Rick Bates wrote:

>And sometimes, you have to reboot the computer because the (USB to)
>serial driver goes wonky and that's the simplest recovery.
>
>Yes saw you changed computers; just submitting it for completeness.
>
>73 es Merry Christmas,
>Rick wa6nhc
>
>Tiny iPhone 5 keypad, typos are inevitable
>
> > On Dec 17, 2014, at 6:17 PM, Bill NY9H <[hidden email]> wrote:
> >
> > just got it going,,,
> >
> > now i will read that.... while it loads
> >
> > tnx
> >
> > At 09:12 PM 12/17/2014, you wrote:
> >> K3 Utility Help, Troubleshooting, MCU Load Failure, has a step
> by step procedure for interrupted firmware loads.
> >>
> >> 73 de Dick, K6KR
> >>
> >> > On Dec 17, 2014, at 18:00, Bill NY9H <[hidden email]> wrote:
> >> >
> >> > oops...
> >> >
> >> > tried to load new fw and it got confused.
> >> >
> >> > Now when i try to force load,
> >> > i can not get the utility to give me a
> >> > " send" screen...either one ...all or selected...
> >> >
> >> > and the led keeps blinking and "mcu ld" stays on the k3 lcd;
> >> >
> >> > even changed computers to get a simple hw serial port
> >> >
> >> > which is set to 38.4k
> >> >
> >> > what did I forget ?????
> >> > bill
> >> > ______________________________________________________________
> >> > Elecraft mailing list
> >> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> >> > Help: http://mailman.qth.net/mmfaq.htm
> >> > Post: mailto:[hidden email]
> >> >
> >> > This list hosted by: http://www.qsl.net
> >> > Please help support this email list: http://www.qsl.net/donate.html
> >> > Message delivered to [hidden email]
> >
> > ______________________________________________________________
> > Elecraft mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:[hidden email]
> >
> > This list hosted by: http://www.qsl.net
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