Re: NOT the feedline

Posted by Bob McGraw - K4TAX on Jun 02, 2020; 4:01am
URL: http://elecraft.85.s1.nabble.com/Re-NOT-the-feedline-was-KPA-1500-faulting-on-6m-SWR-issues-tp7661502p7661560.html

Plus there is L1 which is 0.3uH in the circuit and C7 and C8 in the
circuit when in the bypass position.  This does not allow the tuner,
even in bypass mode, to work well as an antenna switch on 6M.

  The capacitors in question are not rated for the RF current
experienced under certain load Z conditions.  They heat, change value,
and the SWR creeps up.  Allow them to cool and the SWR is back to the
starting point.    I usually tweaked mine such that the SWR started off
a bit high, came down as I transmitted and if transmitting a bit longer
the SWR increased.   Later I got tired of this and changed the group of
disk ceramic caps to 470 pf Russian doorknob caps.  Problem solved.

73

Bob, K4TAX


On 6/1/2020 10:08 PM, Jim Brown wrote:
> his might be it, Peter. ! I've used (and loved) the Ten Tec 229 and
> 238 tuners, but some of their fixed capacitors are under-rated for
> power. This is fairly well known among Ten Tec users, so I read about
> it somewhere and replaced those in my tuners with caps having higher
> power ratings.

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