[Elecraft] SWR safe levels question

[Ron D'Eau Claire]

One "problem" with almost all SWR meters is that they are designed to show
when the SWR is 1.0:1 As the SWR rises, most meters are notoriously
inaccurate. Also, even short lengths of coax between the K3 and the external
meter can alter the indicated SWR, even on the higher frequency bands.
Theoretically that would not be the case, but even a small SWR on the line -
too low to notice on the meter - can be enough to cause a significant
difference at various points along the transmission line. 

I recommend leaning on the K3's SWR meter over the tuner. 

With today's "fixed tuned" rigs, a mismatch results in heating in the finals
as the power transfer becomes less and less efficient due to the impedance
mismatch between the finals and the antenna. More current is drawn by the
finals for a given output power. How much heating you experience in the
finals depends upon the power level and duty cycle of the transmission. 

The K3 has robust self protection. Assuming you have a K3/100, the unit
monitors both the PA heat sink temperature and the SWR. You will get
warnings if either is too high and, if the PA heat sink temperature exceeds
85C, the K3 will automatically switch the KPA100 amplifier module into
standby to protect it. (You can monitor the PA temperature itself as
described in the Owner's manual.)  Also, since current required by the
finals increases with the mismatch, you may get a high current warning if
the SWR is too high. 

I wouldn't worry if as long as I am not seeing any of these symptoms.  

Ron AC7AC

-----Original Message-----

Getn's

I have been searching for the "safe" swr level for the k3.   The reason 
that I ask this is because the SWR reading on the k3 is differnt than my 
MFJ 259 and the meter levels on the front of my tuner.

My tuning procedure is to have a switch in the antenna lines so that I 
first look at the mfj to dial in a very low SWR value.

Then I switch the radio back in line and use the tune feature at 15w to 
check the settings.  Sometimes they are spot on with the 259 other times 
they are not.

When I transmitt I also get the SWR bouncing on the amp meter and the k3 
if I try to tune to the lowest number on the k3 instead of the meter on 
the tuner.

So what is the correct thing to look at and is this normal

Setup is a barefoot k3 to a mfj 962d tuner.  Current antenna is an Alpha 
Delta Trapped dipole.

I am not haveing any problem, just trying to understand what is 
reallying happening in the system.

I think that I over think this way too much but if I could find a real 
referenc for max swr for the k3 and understood what I am looking at it 
could make me a better operator.

Thanks
~73
Don
KD8NNU
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