Re: my KPA1500 and 160M

Posted by Adrian-3 on Sep 02, 2020; 10:55pm
URL: http://elecraft.85.s1.nabble.com/OT-WWV-Time-Transmissions-tp7664561p7664625.html

The problem is evident on first KPA1500 match attempt before any heating
of the balun core is possible. It is not a core heat issue at all.

If it was the OP would be able to get an ok initial atu match, that
would then deteriorate with core heat..The issue is from the get-go.

Also only current in the balun  circuit produces emf and therefore core
heat. Voltage is only a factor in how much current flows depending

on circuit impedance, Plenty of voltage with no current = no heat.


On 3/9/20 3:25 am, David Gilbert wrote:

>
> More likely that the ferrite core is getting hot from excessive VSWR. 
> High current could, but rarely does, heat up the coil, but it's high
> voltage which often heats up the core.  At low power (and therefore
> low VSWR voltage) it wouldn't necessarily be a problem, but at high
> power it easily could.  I know this from personal experience with a
> 160m Inverted-L that initially had a high VSWR that with high power
> heated up a MUCH better common mode choke (homebrew per K9YC
> guidelines) than the Balun Designs stuff.
>
> 73,
> Dave   AB7E
>
>
>

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