Case Temperature of RX-888

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Guy Atkins
Posts: 22
Joined: Wed Aug 19, 2020 5:21 pm

Case Temperature of RX-888

#1

Unread post by Guy Atkins »

I was curious to learn how hot the RX-888 would get after an hour of continuous 32 MHz bandwidth operation, so today I did before and after measurements of the outer case.

My upstairs office was quite sunny and warm today, and the ambient temperature of the RX-888 in this setting was 31.4 C. / 88.5 F. Temperature was measured with an infrared thermometer.

After an hour of operation the radio's case had no overly-hot spots that I could find and the enclosure was a uniform 44.1 C. / 111.3 F.

In my opinion the heat sinks on three sides of the case, and the internal heat sink on the LTC2208 ADC are doing their job well! I had expected a higher measurement in this overly-warm, sunny room.

73,

Guy Atkins
Puyallup, WA USA

fei666888
Posts: 18
Joined: Sun Oct 04, 2020 8:54 am

Re: Case Temperature of RX-888

#2

Unread post by fei666888 »

The LTC2208 is an ancient chip. The power consumption of 1.25W brings a lot of heat. It has to add a lot of heat sinks, but it has been tested for a long time without any heat dissipation. Although the ADC temperature is extremely high, it still Can run stably

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sm6fhz
Posts: 179
Joined: Wed Aug 19, 2020 3:21 pm
Location: JO57XJ
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Re: Case Temperature of RX-888

#3

Unread post by sm6fhz »

Hi all.
I did some experiments with active cooling of my RX-888. I placed two 40x40x20mm, 12V fans on top of the top cooler of the RX-888 and fed them with reduced voltage (from a USB outlet of laptop) for lower acoustic noise. They fitted very nicely on top of the cooling fins and were easy to fasten into the correct position with small screws.
Room ambient temp +23C. Running 32 MHz sampling BW.
No fan attached: Stabilize at +43C case temperature close to the main cooling fins. Delta T of 20C up from room ambient. Cooling fins on the RX-888 facing upwards.
Fan running at 3.8V: Stabilize at +34C case temperature. Improvement of 9C. Very low acoustic noise. (the 3.8V comes from a 18 ohm resistor in series with the +5.0V from the USB outlet)
Fan running at 5.0V: Stabilize at +31C case temperature. Improvement of 3C more for a total of 12C down. Higher acoustic noise than with 3.8V.
Lowering the sampling BW to 1MHz reduced the case temp to +30C when using +5.0V on the fan. Not much of an decrease, actually surprising.
Is it worth the effort? Possibly, semiconductors inside will run at a lower junction temperature and thereby increase their life span.
If a FW using 64 MHz sampling will show up for the RX-888, it may be a good idea the use such a active cooling.
73 / Ingolf, SM6FHZ

fei666888
Posts: 18
Joined: Sun Oct 04, 2020 8:54 am

Re: Case Temperature of RX-888

#4

Unread post by fei666888 »

On the hardware, the front-end LPF of RX888 is designed according to 64M. We have actually tried 64M direct mining. USB3.0 speed is sufficient, but there are some problems in the algorithm, which have not been solved yet

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sm6fhz
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Re: Case Temperature of RX-888

#5

Unread post by sm6fhz »

Hi Justin.
Nice to see you here on this forum. I hope you enjoy the discussions here and that you can benefit from the ideas and feedback that comes up for the the RX-666 and RX-888 as well as for the ADALM Pluto implementation you have engineered.
I think there are many that look forward to a RX-888 FW that supports 64 MHz sampling and will be happy to be involved in any testing needed.
I guess that many here also follows your Tweets about your experiments. Keep up the good work.
73 / Ingolf, SM6FHZ

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NO6B
Posts: 53
Joined: Wed Aug 19, 2020 7:06 am

Re: Case Temperature of RX-888

#6

Unread post by NO6B »

My RX-888 gets a little warm after a while, but no more so than my Airspy Mini.

I do see it drift over 3 ppm from initial power up to when it settles some 20 minutes later, so whatever reference oscillator is being used is not very stable.

uvs300
Posts: 5
Joined: Wed Sep 02, 2020 1:35 am

Re: Case Temperature of RX-888

#7

Unread post by uvs300 »

Cold case now and the fan that comes with the cpu heatsink is not powered on.
Used element14
1492-4276/01 between the 888 and heatsink.

Regards
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