Not a cheap solution, but Heil produces a foot switch that sequences the key line. Of course this requires some wiring.
Bill K9YEQ -----Original Message----- From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Don Wilhelm Sent: Thursday, September 29, 2016 1:08 PM To: EA2BD <ea...@yahoo.com>; elecraft@mailman.qth.net Subject: Re: [Elecraft] KX3 temporary high SWR on PTT with external Amplifier Ignacio, The amplifier is not switching to the transmit state within the time between when the KX3 pulls PTT low and the time RF appears. I believe that time is about 8 milliseconds. Yes, your KX3 is working into an open load when that happens - hence the high SWR. That condition is known as "hot switching", and even if it does not eventually damage the KX3 PA, the relay contacts in your amplifier T/R changover will become pitted due to the arcing. One solution is to modify your amplifier with a QSK T/R switch or substitute fast vacuum relays. Another solution is not to use QSK or VOX - connect a footswitch to the KX3 PTT *input* (ACC2 jack's TIP connection) and set the ACC2 IO menu to LO=PTT if the footswitch grounds the connection. Then use the footswitch to put the KX3 into transmit before you operate the paddles or speak into the microphone. In other words, do not turn on VOX. Another way to put the KX3 into transmit mode without the footswitch is to use the XMIT button on the KX3. 73, Don W3FPR On 9/29/2016 12:06 PM, EA2BD via Elecraft wrote: > Hello, > I want to check if anyone experiences the same behaviour when > connecting the > KX3 to an external amplifier. > > - I receintly added an external amplifier to my KX3. > - I connected the PTT cable to the ACC2 port and to the amplifier. > - I set the Menu ACC2 on the KX3 to Active low, as specified. > - I verified if the cable works and it closes contact all right every > time I key down. > > The TROUBLE is: > Everytime I send a dit (CW) or start talking (Voice) the SWR indicator > on the KX3 shows full reading (Hi SWR!) just briefly and it quickly > relaxes down to normal reading (SWR 1:1) during the rest of transmission. > > I believe there should be any kind of delay between the TX on the KX3 > and the TX on the ampli, that causes the momentarily Hi SWR reading... > But this is extrange because the PTT cable is in! > > Does anyone have experienced similar phaenomena? > Any idea to overcome this? > Do you consider there will be a real overload on the finals due to > this small transient time? > > I drive with 2 watt out from the KX3 to get around 90W out from my > Amplifier. > > Wait for your feedback, many thanks! > 73 de Ignacio EA2BD > > > > -- > View this message in context: > http://elecraft.365791.n2.nabble.com/KX3-temporary-high-SWR-on-PTT-wit > h-external-Amplifier-tp7622916.html > Sent from the Elecraft mailing list archive at Nabble.com. > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net Please help support this email > list: http://www.qsl.net/donate.html Message delivered to > donw...@embarqmail.com > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to k9...@live.com ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
