[TowerTalk] KLM 5el 20m monobander - High SWR

[David L. Thompson]

I had one up for several years in the late 1970's along with a 5 el 15 and a
6 el 10.  They were called Big Stickers then.   All use the KLM modified
Oliver Swan log cell and parasitic elements.
The normal SWR curve is backwards from a yagi in that the SWR is low in the
CW band (say 14020) and low again on say 14275.  In between the SWR slowly
rises for 70 Khz and then slowly falls.   In no case was the SWR above 1.5
to 1.

The antenna did use the crossed straps with an insulator in the middle to
keep the straps away from the boom.   There must be a problem with the
reflector or one of the driven elements lengths,  the 200 ohm balun, or the
shorting straps.  I have found the balun (after a few years) no longer
correctly matched 4 to 1 and also the connections that the straps being
loose at even one point caused SWR problems.  And yes, these same problems
occur in the KT34 and 34XA (in spades).   My neighbors complained loudly so
I replaced the stack with the KT34X (early XA),  On 20 and 10 I have never
looked back.  The 15 meter section is the weak link in the 34/34XA...it just
does not play as well and KLM admitted this was the most compromise band.

One other note on the 5 El 20.  At first I had a 4 el 10 and my old Mosley 2
el 40 up and I found the 5 el 20 works as well as a 3 el tri-bander on 15
but bckwards!!!!.   Adding a parasitic element from a tip from W9LT (now
WA7LT) to the 40 meter Mosley gave me a bang up 15 that easily worked Stew
K4SMX at Spratley.  Of course neither worked as well as the 5 el KLM.

Dave K4JRB