My inductors are about 25uH in series and 25uH to ground. Best that I can
calculate from online calculators.
Jim K9TF
On Wed, Nov 13, 2013 at 10:26 AM, Jim GM <jim.gmforum@gmail.com> wrote:
> I have a 253 Auto coupler and MFJ 989B. The MFJ998RT in the shop for
> repairs from abuse. Non of these tuners will tune 160M on their own.
>
> Each of these I had to add an inductor L network for 160M. Everyday I have
> to retune my 99 foot inverted L, unlike 80-10M dipoles that I have had in
> the past. This L network is a hairpin coil to ground and an inductor in
> series with the antenna cause it is short. The Ten-Tec 253 is just a pain
> in the output. Shift freq tune, Sun rise tune, Sun set tune, over and over
> again.
>
> The beauty of the 99 foot L is that the network can be bypassed with
> relays and operate on 80-10 m.
>
> What would I accomplish by adding a 1000pF capacitor to ground for 160M?
> I have seen this suggested many times. With the L inductor network the
> 1000pF cap at the top of the hairpin to ground the cap adjustment on the
> tuners inside the shack can now be adjusted to minimum SWR. With out the
> cap minimum SWR is around 1.4:1 best it can do.
>
> Put all this on a smith chart? I have know idea what my impedance really
> is. All I care is that near 1:1 match in the shack and weather or not I am
> getting more than 60% of my signal out. That 60% I have no idea if I am
> getting that.
>
> BCI from nearby AM station renders my MFJ analyzer just about useless.
> Transmitter reads about SWR 2.5:1 with out the tuner in line.
>
> This is a hit and miss tuning proposition on 160M. Starting to think on
> giving up on the inverted L and shunt feed the 50 foot tower thats next to
> the house. Something tells me I will have the same problems.
> --
> Jim K9TF
>
--
Jim K9TF
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