as the handbook text posted above says, as a first approximation use the LC values of the transmitter plate tank.

the 160M B&W balanced (for push-pull PA) coils are 94 uH and resonate at the bottom of 160 with 90 pF. The handbook recommendation is that the LC tuner tank resonates at 80% of the intended operating frequencies so max of 100-120 pF would be used in a parallel-feed balanced link tuner for 160 using the B&W hdvl or tvl coils depending on power. From what Stefanos is seeing at the input end of his ladder line he should use the parallel configuration.

and make the link variable to dispense with the capacitor on the link side.

I need a small, panel mount 120vac (60cps) variac. 2 amp rating is plenty.
Thanks, Roland

Alan - W4AMV, good material.


[/quote]

Should be 120 ohms, real, anyway still ~ 10 uH.

Some more comments on this and to put this design approach in perspective.

Choosing Lp and Ls might be driven by the loaded
Q of the primary and secondary inductance. On the
50 ohm side, a Q of unity is realized at 1.8 MHz
with an inductive reactance of 50/(6.28*1.8 MHz)
or 4.4 uH, hence its value. On the balanced side
consider the magnitude of the Z termination, about
612 ohms, At a Q of unity, Ls would approach a
value of 54 uH. However, if the reactance of
600 ohms is tuned out at 1.8 MHz, the remaining
112 ohms is set by an inductance of 10 uH. A
range of 10-54 uH with suitable C to tune the reactance
is reasonable. It is the coupling factor, k, that
will significantly alter the final quality of the
match and the return loss. Recall in the earlier
designs of balanced matching tuner systems, a swinging
link was always touted as an ideal final adjustment.   

Even if it is a coaxial set up, the two coils have a distance of 3/4'' between them so K could be less then 0.9.

I used 4 turns for the link coil because this number was right in a previous linked tuner I made for an EFHW (4000Ohm +).

In that case I had the link coil (4 turns) around the cold side of the long inductor (44 turns). It worked perfectly without capacitor in series to ground.

In that case coupling was much better and K was for sure closer to 0.9. The long inductor was factory made and I managed a very tight coupling, may be less then 3/8''.

In any case if I'll count around 10uH when in place then with a var. cap and 1300pf in series to ground  I'll adjust it to the desire XLS.

In my calcs, the calculated coil inductances were for free coils by themselves.

If one is concerned with the Mutual Inductance, then
M ~ = (Ns X Np X Area)/length of coil.

M also is = k X SQRT(Ls X Lp)  where k is the coefficient of coupling.

If k ~= 0.9 for a coaxial set of coils, then M = 0.9 X SQRT(3.5uH X 35uH) = 0.9 X 11.1uH = 10uH.

The L/C ratio is driven by the complex line Zo with the antenna attached and the desired matching bandwidth, that is operating Q. A good treatment of the details is in the handbook, example the '63 treatment in the chapter on transmission lines. See copy of excerpt attached. There in Ch 13, the series and parallel balanced line tuning is addressed.

Hi Peter,

What values would you propose for L and C in a sircuit like the one in the attachment?
Single band use p.e 1850Khz, 50Ohm to 120+600jx impedance.

Stefano

Hello Dave!
Some stations and me heard you talking on 29030 khz in AM.
I am thinking about the time

It must be around 17.30 hour Summertime by us, that is 15.30 GMT time.
I heard you sometimes very good on my own radio: Kenwood R 5000.
And I listen in our livingroom.

But evenso on my pc (old laptop), by a webreceiver I listen to these:

http://173.48.189.54:8074/
KiwiSDR: Software-defined receiver
ASHLAND MA USA | Grid FN42FG
, ASL 90 M, [map], SNR 25/17 dB
Antenna: MAG LOOP 80M DIPOLE

Hi, hi....
On my radio I heard Dave, WB1EAD

And on the Kiwi SDR in the USA: John Petters, G3YPZ
From the UK (England)

I were wondering how good I could hear mostly both stations!
Dave good by me, in The Netherlands...
John good on the webreceiver in USA...

A very nice qso!

I were only listening, while we drinking coffee...
We were just at home from shopping....


Greetings,

Henk / pe1mph
Dokkum / The Netherlands