[Elecraft] K3 power reduction due to high SWR

[KU7Y]

It all depends on just what he means by 72 ohm cable TV coax.

If it's the low quality coax used around your TV's, you might be right.

But if it's the 1/2" CATV hardline or the smaller "drop" cable, the loss 
will be much less.

These last two are quite good and have very low loss.  I have used just 
under 300' and did quite well with both QRP and QRPp.

It used to be that you could go to your local cable TV company and get lots 
of left over pieces of that good coax.  No idea how that works now but sure 
worth a try.

So Dave, I'd say to use whatever you have and get on the air.  Then spend 
the rest of your life making your antennas bigger, higher and better!

OK, back in my hole,

Ron, KU7Y
SOWP 5545M
Arizona Outlaws Contest Club
Brenda, AZ (Winter)
Caldwell, ID (Summer)
ku7y at qsl.net
http://www.hatpinsandmore.com
----- Original Message ----- 
From: "Adrian" <vk4tux at bigpond.com>
To: <elecraft at mailman.qth.net>
Sent: 04 April, 2012 8:00 PM
Subject: [Elecraft] K3 power reduction due to high SWR


> 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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