[Elecraft] KPA500 Faulting on high SWR on power rise

[Bob McGraw K4TAX]

I question the 4:1 balun being the correct nor best choice. Typical of that antenna the feed Z of the radiator is more likely 25 to 35 ohms. The 4:1 balun is presenting something like 10 ohms to the tuner. Worst case for high current and hi loss in the tuner causing heating.   A 1:1 balun would seem more likely correct. 

Many seem to "think" a 4:1 balun is correct when using open wire or a balanced line to "match the line". 

Bob, K4TAX


Sent from my iPhone

> On Feb 24, 2018, at 8:59 PM, Jim Brown <jim at audiosystemsgroup.com> wrote:
> 
> Someone should tell the electrons. UHF connectors have been standard on legal limit power amps for as long as I've been a ham.
> 
> 73, Jim K9YC
> 
>> On 2/24/2018 1:46 PM, Walter Underwood wrote:
>> The Amphenol voltage rating for UHF connectors is 500 V peak. So the connectors could be another weak point.
>> 
>> https://www.amphenolrf.com/connectors/uhf.html
> 
> 
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at 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 rmcgraw at blomand.net
>