[Elecraft] K3 power reduction due to high SWR

[Adrian]

You have some serious performance limitations with this setup.
If I have to use your antenna, then my move would be to replace the 250' of
75 ohm coax with 250' of 450 ohm ladder line, check the fan dipole legs are
exactly the same to provide a balanced load.

Get a balun  and short 50 ohm coax section to get from the ladder line back
into the shack, if you can't get the balanced line in to a balanced line
tuner etc.

As it is you are losing 57% @ 20m of your power in that feedline.

A mfj-986 or similar with balanced line is probably the go on a limited
budget.

You will reduce loss from 57% to 9%.

Adrian ... vk4tux

-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of David Stratton
Sent: Thursday, 5 April 2012 10:34 AM
To: Elecraft Reflector
Subject: [Elecraft] K3 power reduction due to high SWR

At what point does the SWR have to rise up to before

the K3/10 output power begins to decrease? 

I have been using a TS-830 which is not bothered by 

SWR up to at least 3:1. I cannot get the tuner now so

will I be forced to run very low power if my SWR is 2

or 3 to 1? What about the K3/100? 

 

My antennas are resonant fan dipoles (80, 40, 20, 17)

fed with 250 feet of 72 ohm cable TV coax. 

 

Dave - KO4KL

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