Re: KPA500 Faulting on high SWR on power rise

Posted by Bob McGraw - K4TAX on Feb 25, 2018; 3:30am
URL: http://elecraft.85.s1.nabble.com/KPA500-Faulting-on-high-SWR-on-power-rise-tp7638486p7638553.html

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 <[hidden email]> 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
>
>
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