Heatsinks are falling off in 6400 and 6600 models.

  • 4
  • Problem
  • Updated 1 year ago
  • In Progress
As part of the Product Enhancement Notification (PEN) or Recall.  If you want to know where to look to
see if both of your heatsinks are in place and have not fallen off.  Here are some photos to look at.
Photo of Tom Teague

Tom Teague

  • 21 Posts
  • 6 Reply Likes

Posted 1 year ago

  • 4
Photo of Gerald - K5SDR

Gerald - K5SDR, Employee

  • 830 Posts
  • 1515 Reply Likes
Official Response
Hello all,

Please let me clear up some of the FUD (Fear, Uncertainty, and Doubt).  I designed this part of the radio so you are getting it right from the horses mouth.  That means you can blame it directly on me.  I apologize for any inconvenience you may experience while we do the heat sink replacement.  

Here are the facts regarding the ADC heat sinks:
  1. The AD9467 ADCs do not require heat sinks to safely operate.  We have been using these parts first in government and later in ham applications for 10 years and have never used a heat sink on the parts until the new radios.  That means there are no heat sinks on the 6300/6500/6700 ADCs and they have been in continuous operation since 2013.
  2. The AD9467 has a maximum junction temperature rating of 150 Centigrade (302F).  It is rated  to operate in an ambient temperature of 85 Centigrade (185F).  There is NO risk of damage to the part in your radio with no heat sink.  The PCB is designed to sink the heat into two layers of ground plane through 36 ground vias on the chip's ground pads.  This will keep the chip perfectly safe without an external heat sink.  We will not replace the boards because there is no sound technical case to do so.
  3. The heat sinks were added to increase to increase spurious free dynamic range by a few dB and to hold the clock alignment within a tighter range.
  4. Each time you boot the radio, it does an automatic synchronization of the ADC clock with the FPGA to find the optimal timing.  If the heat sink falls off, the timing of the clock changes and it may lose sync.  This causes the noise floor of the receiver to go up dramatically or you can lose receive all together.  Since the entire system is clocked through the first ADC, it can affect transmit as well.
  5. Simply replacing the heat sink with a tie rap to hold it in place as others have shown here will get you right back in operation if you have not yet received the replacement heat sink kit.
  6. The copper heat sinks we used were selected because they are copper, cost effective, easy to get in volume, and fit the part well.  They were marketed to be used on the Raspberry Pi chip.  Unfortunately, the quality of the thermal adhesive was not what we expected.  
  7. The adhesive problem did not show up on our prototypes or on our our alpha/beta test team until three months after being placed in operation.  
  8. The thermal adhesive on the new heat sinks are rated to require 36 pounds of force at 100C (212F) to remove them after they are properly applied.  
  9. The radios are rated for an ambient temperature in operation of 50C (122F) so I doubt any of you have gotten near the maximum ambient operating temperature of the chip of 85C (185F).  If you have, you are a lot tougher than me.  ;>)
  10. Why didn't I use the heat sink on the bottom to begin with?  Of the thousands of design decisions you get to make in designing a radio, I just didn't think of it.  I had no idea that the adhesive would fail on the one I chose and it was fine thermally to meet the requirement.  I learn something new with each new design.
  11. We have mailed kits to everyone who requested it when we communicated the PEN announcement.  Please complete the survey in the notification if you have not already to receive your kit.
That is the whole story.