[Elecraft] KPA-1500 Efficiency As A Function of Input Power

[Lynn W. Taylor, WB6UUT]

Isn't there a rule about using the minimum power necessary?

On 8/17/2018 11:20 AM, Wes Stewart wrote:
> Do they?
> 
> I have a KPA500, not a '1500 but I run mine full tilt on RTTY.
> 
> Something to bear in mind in this discussion is that we run our 
> equipment in ICAS, not CCS.  Even in a contest situation we probably 
> only transmit half the time.  During the off (RX) time the amp isn't 
> drawing any plate, collector or drain current, nor is it drawing much 
> current on CW, key up or SSB between syllables. RTTY is a "continuous" 
> mode without the syllabic breather, but it's still intermittent.
> 
> Wes
> 
> On 8/17/2018 6:43 AM, john at kk9a.com wrote:
>> So why do most RTTY users run their amps at reduced power?
>>
>> John KK9A
>>
>>
>> From: Charlie K3ICH
>> Date: Fri Aug 17 09:24:18 EDT 2018
>>
>>
>> I really do NOT understand why this data is so surprising.
>> It all seems to me to be perfectly normal with the amplifier's highest
>> efficiency occurring at near max output.
>> Which curiously, I would assume,  is the way the amp was designed.
>>
>> Think zero output with zero drive = zero efficiency.
>> Apply some drive, read some output and the efficiency goes up from there.
>>
>> 73, Charlie k3ICH
>>
>>
>>
>>
>> -----Original Message-----
>> From: elecraft-bounces at mailman.qth.net <elecraft-bounces at
>> mailman.qth.net> On
>> Behalf Of john at kk9a.com
>> Sent: Friday, August 17, 2018 8:57 AM
>> To: elecraft at mailman.qth.net
>> Cc: charles at k5ua.com
>> Subject: [Elecraft] KPA-1500 Efficiency As A Function of Input Power
>>
>> Interesting data, Charles.  I assumed that running the KPA1500 (or 
>> KPA500)
>> at lower power would keep the fan from running as much. I knew that
>> efficiency changed with output power but I did not expect that it was 
>> this
>> significant. If your data is correct there is 1000++ watts of heat to
>> dissipate no matter what power level you use.
>>
>> John KK9A
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:Elecraft at mailman.qth.net
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to wes_n7ws at triconet.org
>>
> 
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to kx3.2 at coldrockshotbrooms.com