I use the "Key Out" line of my K3S to drive the base of a homebrew transistor switch that, in turn, drives a relay coil at the base of my antenna. There is an isolation diode between the K3S keying line and the switching transistor because I also use the same keying line to switch my AL-1200 QSK amp. I run full QSK with a Gigavac GH-1 vacuum relay as the switching relay at the antenna. I set the QSK delay in the K3S to 10 ms and the GH-1 has a closure time of 6 ms. It works fine. I've never had an issue with hot switching in full QSK.
73, John W1FV -----Original Message----- From: Topband [mailto:[email protected]] On Behalf Of James Wolf Sent: Saturday, September 23, 2017 8:08 PM To: 'Richard (Rick) Karlquist'; 'MR TREVOR DUNNE'; [email protected] Subject: Re: Topband: Relay switching at the base on antenna Trevor, I suspect you may be trying to detune the tower during receive, which I plan on doing here as well. Check your transceiver Amplifier Key Output line. That line should close about 10ms before any RF output from the radio occurs, for the very reason Rick mentions below. Any suggestions for the group on which relay to use for this? I don't want to give up my QSK. Jim - KR9U --------------------------- >There is nothing simple about this, because you need to avoid hot switching. This means that you need to start with the rig signal that is intended for use with QSK linears. This signal will change to the transmit state 10 ms before the transmitter actually starts putting out RF. The name of this signal will vary depending on the rig, and the "PTT" signal may or may not be the correct one. Additionally, in some rigs you may need to put a switch in the QSK position (such as the FT1000). >Once you have a 10 ms head start, you need a relay that will close in >less than 10 ms. If necessary, you can use speed up circuits that put a temporary overvoltage on the coil of the relay. This requires that the relay is energized on TX and non-energized on RX, rather than vice versa. >In keeping with the word "simple": a piece of hook up wire running to >the base of the antenna is much simpler than trying to send DC on the coax, depending on how hard it would be to install this wire. You can still use the shield of the coax as the return connection. >Rick N6RK On 9/23/2017 5:39 AM, MR TREVOR DUNNE wrote: >> Hi All > > >Can Anyone tell me a simple way to switch a 12v relay at the base of > >an antenna using the rigs ptt as the trigger?? _________________ Topband Reflector Archives - http://www.contesting.com/_topband _________________ Topband Reflector Archives - http://www.contesting.com/_topband
