[Elecraft] Advice!

[Dick Dievendorff]

At low heat levels, the fans operate at low speeds.

As the temperature of the PA rises, the fans increase in speed (and they're
louder).  Depending on humidity, ambient temperature, and the free space
around the amplifier, the increased fan speed moves  heat energy out of the
amplifier.

If the PA transistors get "too warm", the firmware causes a
temperature-related fault.  That shuts the amplifier down until the
temperature returns to a safe level.

During development a number of amplifiers were subjected to very long key
down times, sometimes with restricted airflow.  We've exercised the
protection logic quite a bit.  That doesn't mean you need to run with all
the knobs to the right, but if the fans are running, that's good, heat is
being moved out.

The PA devices are not being operated at their maximum thermal rating. The
KPA500 temperature fault occurs before the RF transistor manufacturer's
maximum temperature rating.

Dick, K6KR


-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Phil LaMarche
Sent: Saturday, July 30, 2011 11:49 AM
To: elecraft at mailman.qth.net
Subject: [Elecraft] Advice!

When running the KPA500 on AM, it there any time limit before unkeying?
While operating, the fan comes on and then it kicks into another speed.

 

Thanks

 

Phil

 

Philip LaMarche

 

LaMarche Enterprises, Inc

 

 <mailto:Phil at LaMarcheEnterprises.com> Phil at LaMarcheEnterprises.com

 <http://www.lamarcheenterprises.com/> www.LaMarcheEnterprises.com  

 

727-944-3226

727-937-8834 Fax

727-510-5038 Cell 

  <http://www.w9dvm.com/> www.w9dvm.com

K3 # 1605

KPA500 # 029

 

 CCA 98-00827

CRA 1701

W9DVM

 

 

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