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-requ...@mailman.qth.net wrote:
Message: 7
Date: Wed, 28 Aug 2024 10:12:45 -0400
From: "Dave New, N8SBE"<n8...@densbe.com>
To: Elecraft Reflector<elecraft@mailman.qth.net>
Subject: Re: [Elecraft] K3 shuts down
Message-ID:<acf43bf9136c4cac35a51eb2f1d88...@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!
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@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 arch...@mail-archive.com
