Elecraft has a fix for this.
73,
Scott K9MA
----------
Scott Ellington
--- via iPad
> On Aug 18, 2018, at 1:55 PM, Paul Baldock <p...@paulbaldock.com> wrote:
>
> I just checked mine on 40M and when on CW Temp is bouncing all over the
> place. Same into a dummy load as the antenna 300ft away. It also does it to a
> lesser extent on 80M and a little bounce on 17M and 10M.
>
> I suspect its in the amp and not related to common mode RF in the coax.
>
> Probably a cap in the right place would fix it.
>
> - Paul
>
>
> At 11:20 AM 8/18/2018, you wrote:
>> Some baluns offer good common mode current rejection while others offer
>> virtually no common mode rejection.  {See DJ0IP site and discussion on
>> baluns.}Â Since the feed line from the balun runs down the tower to the
>> point where the feedline runs underground, that segment of feedline is
>> exposed to radiation from the antenna. Certainly common mode current can
>> be a very realistic occurrence in this case. ..........." it's some sort of
>> new hyper-super-ultra-infina-deluxe type never before discovered on earth."Â
>>  Nope, it is just basic physics regarding the properties of RF induced
>> currents.   Depending on band, a choking impedance of 300 to 5000 ohms
>> may be needed to resolve the issue.  Since it was disclosed as power
>> related, this supports the issues of common mode currents. Good luck in
>> finding and correcting the matter. 73 Bob, K4TAX On 8/18/2018 12:20 PM, Jeff
>> Blaine wrote: > Odds are not good there. The antennas have a balun at the
>> feedpoint, > are on a tower 500 feet from the shack and the hardline runs
>> under > ground. If there is common mode involved, it's some sort of new >
>> hyper-super-ultra-infina-deluxe type never before discovered on earth. > >
>> 73/jeff/ac0c > alpha-charlie-zero-charlie > www.ac0c.com > > On 18-Aug-18
>> 7:12 AM, Bob McGraw K4TAX wrote: >> I'd say a bit of common mode current on
>> the feed line.   I see that >> from time to time with my KPA500 on
>> certain bands/antennas. >> >> 73 >> >> Bob, K4TAX >> >> >> On 8/17/2018
>> 11:45 PM, Jeff Blaine wrote: >>> While running the KPA1500 in the SARTG
>> tonight, I noticed that the >>> temp reading drops about 10C when
>> transmitting. min fan speed 1. >>> >>> Seems to be related to power - at
>> 1500W it's pretty close to 10C. At >>> lower powers, it's less of a
>> difference. I don't recall seeing that >>> before. >>> >>> Normal? >>> >>>
>> 73/jeff/ac0c >>> alpha-charlie-zero-charlie >>> www.ac0c.com >>> >>>
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