Thanks for the reply, Curt. No, I have not thought of a good way to simulate the switching without the T-4XC and still have similar timing of the RF load. The muting method in the NC-300 is simply opening the cathode circuit (same method as used with the RX / TX switch on the receiver. I suppose if there is enough capacitance in the cathode circuit, there could be a very small delay in shutting down the RX. A bad or leaky bypass cap might exaggerate that. Simply turning the RX / TX switch on the receiver on and off is very quiet, but, of course, there is no simultaneous RF load. That is why I suspect that the RF is hitting the receiver before the RX circuits are completely shut down.
If necessary, I could look into muting the RX with a bias source that is switched within the TX (would need -22 to -50 volts) to mute the RX using grid block. That would also facilitate QSK keying capability. That is probably a last resort, however, as it would require a little work on the TX, which I would like to avoid for now. Hank ----- Original Message ----- From: Curt To: [email protected] Sent: Tuesday, October 18, 2011 8:09 PM Subject: Re: [Drakelist] Receiver Muting Have you tried seeing what happens when you simulate the same muting in the Rx without the T4x? It might be something in the Rx that does that when it switches. Your suggestion is certainly possible if the Rx Mute response is slow. It does not do this with a R4any. Curt KU8L On 10/18/2011 2:56 PM, Henry Foglesong wrote: I am using a T-4XC with a National NC-300 receiver and am using the receiver mute circuit to mute the receiver. This works well except that when I initiate a transmission with any mode, I get a rather sharp and loud thump in the receiver. It almost sounds as if the rf from the transmitter is hitting the receiver slightly before the transmitter relay switches the antenna and mutes the receiver. Is this typical of that kind of setup, and what, if anything, can be done to minimize the effect? _______________________________________________ Drakelist mailing list [email protected] http://mailman.zerobeat.net/mailman/listinfo/drakelist ------------------------------------------------------------------------------ _______________________________________________ Drakelist mailing list [email protected] http://mailman.zerobeat.net/mailman/listinfo/drakelist
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