Anan 8000 DLE Overheating

N4KMG
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Anan 8000 DLE Overheating

Postby N4KMG » Sun Nov 06, 2022 5:26 am

Good Morning,

I am having a pretty severe problem with my 8000 DLE overheating and going into standby mode frequently. I have raised the radio up by 3-4 inches with spacers but it has not improved the issue. I am transmitting at 100w and turning it down to 25 and 50 watts and it has not helped. I have even tried placing a 5-inch fan directly under the fan on the bottom of the 8000DLE but it has not improved the overheating issue. It boots up at 23 degrees celsius and as I transmit, the temperature quickly rises until it goes into standby mode and I have to reset. Does anyone have any suggestions? Thank you much!

73 de N4KMG
Wes Wingo
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Tony EI7BMB
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Re: Anan 8000 DLE Overheating

Postby Tony EI7BMB » Sun Nov 06, 2022 9:52 am

Is the internal fan running Wes ?
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w-u-2-o
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Re: Anan 8000 DLE Overheating

Postby w-u-2-o » Sun Nov 06, 2022 10:59 am

Same question a Tony.

Also:

Is the fan filter clogged with dust?

What sort of duty cycles are you running? Is this AM or FT8?

Did it ever work or has it always been like this?
K9RX
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Re: Anan 8000 DLE Overheating

Postby K9RX » Sun Nov 06, 2022 1:14 pm

This is a problem that has plagued me forever. The efficiency is terrible at lower power levels (i.e. what 97% of ops need/do to drive an amp)... and if you use it on DIG modes, FT8 or on EME I use it on Q65-60... it will continue to climb until it hits 65° and trips out. Frustrating. I have taken to putting a 20" AC BOX fan in front of it and lifted up the cover slightly. This keeps it from tripping and keeps the temp at around 55°. Note it only does this with prolonged transmitting - i.e. on EME or TB or anywhere you transmit DIG (FT8 included) for more than about 45 minutes.

I've had the unit apart - in 2017 just after I got it and there was a problem.... and my memory is that there is no heatsink per se. Only a heat spreader - a very thick hunk of AL. That is fine unless you continue to operate at lower efficiencies and longer times. I also seem to remember there is space on the bottom to add a heat sink (maybe more than one) and an impingement fan ... I plan on doing that soon.

The fan IS operating but it doesn't go up very much different in speed. I've confirmed that the chip is at the displayed frequency using an IR temperature gun. There is simply not enough heat radiation to keep it from getting up there. Such a HUGE box - and it does this when 991A's and 7300's run this all day long.

Gary
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N4KMG
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Re: Anan 8000 DLE Overheating

Postby N4KMG » Sun Nov 06, 2022 4:11 pm

Tony EI7BMB wrote:Is the internal fan running Wes ?


Yessir, the fan is running. I was curious if there is a way to manually make the internal fan run faster. Also, I have thoroughly cleaned cleaned the radio. I took it apart and it is 100% dust free.
N4KMG
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Re: Anan 8000 DLE Overheating

Postby N4KMG » Sun Nov 06, 2022 4:15 pm

w-u-2-o wrote:Same question a Tony.

Also:

Is the fan filter clogged with dust?

What sort of duty cycles are you running? Is this AM or FT8?

Did it ever work or has it always been like this?


I am using it only for SSB Phone operation at this point and it has only recently started to overheat
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w-u-2-o
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Re: Anan 8000 DLE Overheating

Postby w-u-2-o » Sun Nov 06, 2022 6:19 pm

On the 8000 the fan is controlled by a PWM fan controller IC located on the power amplifier board. Here is a schematic snippet:
Capture.JPG
Capture.JPG (30.04 KiB) Viewed 2102 times


You can unplug the fan from J6 and wire it directly to 12V so that is always runs full speed.

It is also fairly trivial to replace the fan with a much more powerful, albeit potentially more noisy, fan. The Apache design team has always put a high premium on quiet operation. Some might say too high a premium at the expense of thermal performance. Although, as has already been pointed out, the thermal design of this and other ANAN models is far from optimum.

Here is the data sheet for the factory installed fan in my 8000. You can use that as a guide in potentially selecting a more powerful fan:

https://media.digikey.com/pdf/Data%20Sheets/Sunon%20PDFs/MEC0251V3-0000-A99.pdf

One possibility might be the Noctua NF-F12 iPPC PWM 12V 3000RPM 120mm. Looking at CFM is not enough, you really need to make sure the fan curve shows better performance at all possible static pressures.
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Re: Anan 8000 DLE Overheating

Postby K9RX » Mon Nov 07, 2022 1:21 pm

My first suspicion was that the TC652 was not thermally bonded to the heat spreader ... but using the IR gun I can clearly see that its temp is the same so it is not at fault. Unfortunately, it is not aggressive enough. If 65 is the trip point then you need the fan to be at full speed BEFORE you get to that temp - it barely changes speed. I have always been annoyed with the fan running with the rig 'cold'. I.e. all the time at a minimum speed. I'm hoping that I can add a heatsink, possibly more than one depending on available space on the bottom of the spreader plate - to allow the fan or a/all fans to be off if the temp is below say 40°C and be more aggressive in how it goes up in speed.

Its been years since I had it apart and my recollection is that there was room for a heatsink... but there's been so much DX activity of late that I've been working stations and using the rig.

Alternatively, and I've not checked into this yet, would be to switch the 'set point' of the SMPS for the mosfets ... I suspect they'd run more efficiently if the voltage were at 25 or 30V rather than 50V. This would be when running lower output power which as mentioned the vast majority of users are doing.

Gary
K9RX

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