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Re: LF: TX Toroid Material

To: [email protected]
Subject: Re: LF: TX Toroid Material
From: DK7FC <[email protected]>
Date: Sat, 17 Oct 2015 17:56:20 +0200
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Hi Ken,

I would first transform to 50 Ohm using a BIG ferrite core and then use iron powder cores to build the LPF. T-200-2 types work fine on MF for decent power levels :-)

73, Stefan

Am 17.10.2015 17:41, schrieb Ken:

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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