Temperature and fan speed Flex 6500

Tom K3TF

I have a Flex 6500 I have been using on CW for about 3 months. Running vs 1.10.16. I run 100 watts into a low SWR antenna.

Typical CW transmission 5 minutes on, 5 off, I run 30 to 35 wpm. Using DDUtil before transmission the internal temperature about 10 degrees F higher than the room. Shack typically at 70F. Flex at 80F. As I send CW the temp rises to about 125F during a 5 minute transmission then cools down over 5 minutes to about 90F than repeats up to 125F on next 5 minute transmission. Fans do not change speed as far as I can tell. 

1. Is this typical?

2. Are there any specs on when the fans will increase speed at a specific temperature?

3. Are the fans supposed to increase speed?

4. At what temperature will the Flex 6500 fail or stop transmitting?

Thanks for any information.

73,
Tom
K3TF.....

K9DUR

The fans switch to high speed when the PA temperature reaches 70 deg C (158 deg F).
-- 73, Ray, K9DUR

Tom K3TF

I should have read more before sending this out.

The two internal fans on the chips are constant speed all the time.

The two large fans on the front sides are 2 speed. Low all the time and they switch to high speed when the PA temp reaches 158F or 70C. 

This was from information a couple years ago. My guess is this still the way it works.

Rig works great. Just trying to figure everything out.

Tom K3TF.........

Tim - W4TME

Answers to questions:
Q1: Reasonable.  Since airflow around the radio impacts its cooling efficiency, there isn't a "typical" value.

Q2: The chassis fans will spin up to high when the internal temp reaches 60 deg C (140 deg F)

Q3: Yes

Q4: The radio will generate an excessive thermal condition warning at 100 deg C (212 def F) and shut down at 120 deg C (248 def F).  Personally, I have no recollection of anyone every experiencing a thermal shutdown.

Tom K3TF

Tim,

Thanks for the info. The Flex 6500 is working fine. Just wanted to know.

73,
Tom.........

Tim - W4TME

One other thing I forgot.  We also monitor the RPMs of the CPU fans and if they fall below the minimum threshold, this will shut sown the radio.  This happens way before the internal temperature gets near the thermal warning threshold.  The key takeaway is we have implemented redundant checks to prevent thermal damage to critical components in the radio (ADC, FPGA, PA transistors, etc..).

K9DUR

Tim, is the temperature at which the fans change speed different for the different models?  My SDRMonitor program changes the color of the temperature display at 70 deg C.  I thought that was the threshold for my 6700.  Am I wrong, or are the 6700 & 6500 different?  Is so, what about the 6300?  If there are different thresholds, then I will modify my program to interrogate the radio as to model & adjust the thresholds accordingly. -- 73, Ray, K9DUR

Tim - W4TME

There is a story here.  When this first came up, we looked at the code and the variable for the fan threshold was indeed 60C.  After several comments indicating it was 10C higher, we took another look at the code.  Seems like there was an "orphaned" variable in play.  New logic was added for a hi temp and low temp threshold that defined two new variables.  The hi temp threshold for turning the fan on high is, in fact, 70C.  And the fan will revert back to low speed when the temp reaches 55C to provide some headroom to prevent the fan from cycling hi/low to frequently.

K9DUR

Tim,  TNX.  Looks like my code is good as it is. -- 73, Ray, K9DUR

Dave S

Good stuff Tim, thanks,\Dave / KE1AV