Hi Ken,
I believe two of your component values are off.
I calculate 201µH for the L next to the tubes,625pF for the shunt C and 1.1mH
for the second L .
For the 201µH L I would use iron powder (Amidon #2), for the 1.1mH #43 ferrite.
Use the mini toroid calculator to find the appropiate size regarding number of
turns and
allowed flux with safety margin.
73
Clemens
DL4RAJ
>-----Original Message-----
>From: [email protected]
>[mailto:[email protected]] On Behalf Of Ken
>Sent: Saturday, October 17, 2015 5:41 PM
>To: [email protected]
>Subject: LF: TX Toroid Material
>
>Dear All. I am having problems with the choice of material for
>the output network of the 475kHz Valve TX. The network is an L
>? C ? L, ?T? network with an input impedance of 2100 ohms and
>a load of 50 ohms, for this configuration the input L is
>7.7mH, shunt capacitance is 117pf, and output L is 1.1mH. The
>PA design using a 6146 low power or 813 high power work fine
>when simulated using LT spice IV. When testing in the real
>world using the 6146 there is in excess of 800v rms rf on the
>network side of the anode coupling capacitor, but nothing
>after the input L. I can only conclude that I using the wrong
>type material for the toroids, I used the largest size
>(unmarked) toroid which gave me a modest number of turns. I
>have checked the Amidon tables and Iron Powder because of the
>low AL values, which leaves Ferrite, which mix would you
>recommend? The simulations give me output powers 90W for the
>6146, and 300W for the 813. I would be grateful for any core
>material advice .
>
>
>
>Ken Wright.
>
>M0KHW
>
>
>
>
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