[Elecraft] slinky warts

[Ron D'Eau Claire]

The ones I've seen use a copper-clad steel slinky. I believe the
military ones use the same copper clad design - that may be where those
special-purpose "slinkys" come from. Sure handles the 'rust' issue
better than steel. 

Yes, a lot of inductance will act like an r-f choke. And if you resonate
that "choke" with series capacitance it won't be a choke any longer!
(Try that with an r-f choke in your transmitter and see it suddenly quit
being a choke as is goes up in smoke!). All it takes is the right series
capacitance -which can be considerable if you have a lot of inductance
and a high enough frequency. Probably more series C than most tuners can
provide. Also ATUs, especially the popular "T" matches, get very
inefficient at wild impedance extremes. 

A bigger problem that I find with multiband verticals is that the angle
of radiation starts rising very quickly once it is more than 5/8
wavelengths long. Go much past that length and a low dipole might work
better.  Less "ground" loss - maybe even some reflection gain from the
earth below - and as good or better angle of radiation for most
contacts. 

Ron AC7AC
K2 # 1289


Helm  WB2ADT wrote:
-It's not a multiband antenna.  It has to be adjusted to resonance for
the band desired, even with a tuner.  My 40 meter job will work on 20
but at higher frequencies it starts acting as an rf choke.  After all it
is just a big coil.

-Same thing on receive.  Going off frequency it seems to die.  Must be
brought into resonance.  This of course can be a pain if its hanging in
the attic.

-Will rust after a long period of time.  Fogging on some WD-40, helps
alot.

-another pronounced effect is that with large temperature changes the
SWR goes off by .6-.9. The tempered steel it's made of.