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Joined: Sun, Feb 6th 2011, 20:24 Roles: N/A Moderates: N/A

Latest Topics

Topic Created Posts Views Last Activity
Delta loop 4NEC2 model Nov 28th 2012, 21:27 2 7,282 on 29/11/12
4CX250B cathode driven input impedance Jan 6th 2012, 15:30 1 6,662 on 6/1/12

Latest Posts

Topic Author Posted On
Delta loop 4NEC2 model IW3GHD on 28/11/12
I'd like to post a full parametric 4NEC2 model of a single element (just for now) delta loop antenna which includes a gamma match. If you run the optimizer for example one can find the minimum SWR and/or the resonance condition (min Xin) by playing with antenna perimeter, wire diameter, pigtails parasitic elements, gamma rod length or spacing as well as the gamma capacitance.

4CX250B cathode driven input impedance IW3GHD on 6/1/12
Dear forum,

I'd like to design the matching PI input network for my 2x 4CX250B homebrew cathode driven HF amplifier and furthermore get into a deeper understanding on the optimal energy transferring from the RTX to the amplifier. I couldn't find any helpful in databook or SPICE models of such tubes.
May I get use of the PC-EL software somehow?
What is the cathod impedance in a grid grounded configuration?
Someone said 120 Ohm per tube with 15 pF or so in-parallel capacitance, but I don't have any datasheet confirmation on that.

Thanks indeed

IW3GHD, Stefano

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