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On 10/2/2015 2:34 AM, Jeff wrote:
___ '-----o-----UUU--------------- .-. | ^ | | | | 20 | | C| ' '-' C| 4uH | C| 50 ohms | | --- | . -130--- | | | | v '-----o------------------------ (created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de) Yes that works too. Lots of ways to do it. Brian Oh, yes of course. I try to avoid capacitors as much as I can because one end can float with static voltage while an inductor does not. I've had issues with nearby static lightning discharges. Just my paranoia. To each his own. But it is connected by a 20 ohm resistor. How bad can that be? I don't understand. Do you mean the antenna's feed point resistance of 20 ohms? My understanding of the installation is that the antenna is not directly connected to ground. Am I off track here? My bad. I didn't realize that was the antenna. But the capacitor could be bypassed with a large value resistor if static charge is your concern. A kohm should do the job without impacting the circuit significantly. But wait! Isn't the -130 cap also the antenna then? What capacitor??????????? The 20-j130 is the impedance presented by the antenna at the feed point to gnd, there is no physical capacitor, the 4uH to gnd will provide a dc path for any static. Yes, that is what I said. "Isn't the -130 cap also the antenna then?" I was confused because of poor trimming when someone posted about a different matching network using a capacitor and a reply saying they don't like capacitors because they fail. With the context not being clear I thought they were talking about the capacitor in the diagram with the inductive matching network, but as you say, this capacitance is just part of the antenna. -- Rick |
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