[600MRG] Coil tap clip

[Edward R Cole]

Hmm,

All very interesting.  I recall the tap clips on HF Marine antenna 
tuners were as described.  MY HB loading coil my taps are soldered in 
place after using an alligator clip to find the proper position while 
reading complex Z with my modified MFJ-269B analyzer.  I just tuned 
for resonance, i.e. Z = R +jminimum to place the tap.   Then measured 
for Z = 50 near the ground end of the coil to tap off to match RG-213 
(about 2-1/2 turns).  Z = 50 +j0 only exists at the lower tap and not 
at the end of the 100-foot coax so I suspect some common-mode 
currents even though I use four ferrites on the coax at the tap 
end.  Transmitter load is close enough at about SWR < 1.5 and RF 
ammeter runs 1.4v with 100w output.  The RF current does not shift 
much between the antenna and using a 50-ohm load as termination (thus 
supporting the SWR reading).   So I solder em!

I have three taps installed at present as the inverted-L shifted 
impedance when I shortened the top by 8-feet a couple years 
ago.  Currently its on the ground awaiting a repair from Moose 
dragging and breaking one line.

73, Ed

At 12:55 PM 12/14/2014, William E. Isakson wrote:
>Could you put a wound coil in series with one of the roller coils to get
>enough adjustment for 600?
>
>--------
>
>
>Bill Isakson     AC6QV
>Roseburg, Oregon USA
>bill.isakson at gmail.com
>
>
>
>On Sat, Dec 13, 2014 at 5:26 PM, Merv Schweigert <k9fd at flex.com> wrote:
> >
> > Right Bill,
> >
> > The coil is from some very large LF gear,  its actually a variac, 8 inch
> > diameter and
> > 14 inch log.  wound with 1/4 inch plated copper ribbon.  has a large
> > variable coil
> > inside, close to one end with a shaft to turn it of course.
> > Need to tap the coil to resonate my 160 meter vertical on 475KHZ. and a
> > tap to feed
> > power to the coil up from the ground end.
> > Have some roller coils good for many many KW but they are not large enough
> > inductance
> > wise.
> >
> > Years back would sure liked to have had a bag full of the coil clips for
> > antenna tuners
> > and open wire line I was using.
> > Merv
> >
> >
> >  Hi Merv,
> >>
> >> I have seen those "ribbon wire" inductors. The clips I have (even if they
> >> were available) would be like a chihuahua dog (tea cup size) biting a full
> >> size, salt water crocodile! It probably would hang on very long. But it's
> >> still good to know where I can get the clips.
> >>
> >> 73,
> >>
> >> Bill  KU8H
> >>
> >>
> >>
> >> On 12/13/2014 07:28 PM, Merv Schweigert wrote:
> >>
> >>> Yes see the coil clip from B&W, for coil stock,  nice,
> >>> Need a larger one for flat ribbon stock,  more like a
> >>> 10 amp or larger current size one.
> >>> Old broadcast gear had them ..
> >>> Merv
> >>>
> >>>
> >>
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> >>
> >
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73, Ed - KL7UW
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