[Elecraft] K3 Shuts Down

[Bob McGraw]

> I find running at reduced power may not indeed save anything.  It is 
> just a "feel good issue" issue augmented by "old ham lore".
>
> My K3S running 100 watts on 10M is 43% efficient.  That is 14.0 volts 
> at 16.5 amps for 231 watts total DC input. While running 50 watts it 
> is only 31% efficient.  That is 14.1 volts at 11.4 amps for 160 watts 
> total DC input.   There is part of the power required for earlier 
> stages.  These can likely be constant. However, the numbers show the 
> radio dissipates 131 watts for 100 watts output while at 50 watts 
> output it consumes 110 watts.  The difference in a 50 watt power 
> reduction only nets a 21 watt reduction in dissipation.  Since the PA 
> is protected by a circuit breaker, with some effort one could actually 
> measure the PA efficiency and dissipation at various power levels.  
> After doing so, one might be surprised, they aren't saving anything by 
> operating at lower power but may find just the opposite to be true.
>
> Further studies on my KPA500  indicate at certain reduced power 
> levels, the dissipation exceeds that of those at higher power levels.  
> Case and point from my measurements:  at 500 watts output, 40M the 
> dissipation is 332.0 watts while at 250 watts output the dissipation 
> is 357.2 watts.  Likewise on 20M at 500 watts output the dissipation 
> is 368.0 watts while at 250 watts the dissipation is 404.0 watts.  My 
> point being, reduced power even 20% may actually have higher heat 
> dissipation than rated power output.
>
> If the correct audio level is applied to the K3/K3S and adjusted as 
> specified in the manual or in the Cady book, with the ALC indicator 
> showing 4 bars solid and the 5th bar flickering, there is no danger of 
> having a poor quality signal.    In other words, read the manual and 
> do not rely on what "others" have said. Again, more incorrect "old ham 
> lore".
>
> 73
>
> Bob, K4TAX
>
>
>
> On 9/1/2024 12:20 PM, elecraft-request at mailman.qth.net wrote:
>> Message: 7
>> Date: Wed, 28 Aug 2024 10:12:45 -0400
>> From: "Dave New, N8SBE"<n8sbe at densbe.com>
>> To: Elecraft Reflector<elecraft at mailman.qth.net>
>> Subject: Re: [Elecraft] K3 shuts down
>> Message-ID:<acf43bf9136c4cac35a51eb2f1d88804 at densbe.com>
>> Content-Type: text/plain; charset=UTF-8; format=flowed
>>
>> Also, for digital modes, I run my equipment at half power, max. So, for
>> a 100W XCVR, I run it at 50W.
>>
>> This serves two purposes.  One, it's easier on the PA, and two, it
>> leaves a 3dB 'overhead' for the digital mode, and less likelihood of
>> distortion getting into your TX signal.  This has been SOP for many
>> years for digital modes.
>>
>> A difference of 1/2 S-unit on the receiving end will generally be
>> unnoticed, and your equipment will thank you, as well as any receiving
>> nodes that may not be able to decode your signal if you are pushing your
>> equipment to its limits.
>>
>> 73,
>>
>> -- Dave, N8SBE, Hamshack Hotline 590-0971, HamsOverIP 101018,
>> AmateurWire 1348
-- 
Daddy said there would be days like this!