Re: [Elecraft] K3 Sub Receiver Antenna
I'm not so sure that a BPF would solve the problem even if they are on different bands as the COR may still trip even though the subRX is on another band... ~Brett (N7MG) On Mon, Sep 27, 2010 at 11:38 AM, Don Wilhelm w3...@embarqmail.com wrote: Bill, My answer is not a smart remark, but rather the truth - and that answer is Whatever it takes! There are so many variables that your question cannot be answered specifically for your location. Some of the variables are antenna polarization, physical distance, gain of the transmit antenna and its heading relative to the receive antenna. Trees, buildings and other objects that may shield the receive antenna from the transmit ant, proximity of feedlines, how much radiation is coming back on the feedline for each antenna, plus probably a host of other factors that I may not have thought of. You could make some tests using a simple pickup antenna and a field strength meter at your proposed location for the receiving antenna before placing it. Position the temporary pickup antenna for the least field strength. Unless you have a lot of freedom in the physical location of the receive antenna, the simple solution may be to switch in an attenuator for the subRX when transmitting. If the main and the sub are going to be on different bands, perhaps a bandpass filter would be a good solution - again, the real answer is Whatever it takes, and hopefully you can begin to understand why that is the only answer possible. 73, Don W3FPR On 9/27/2010 12:59 PM, Bill N3KKM wrote: The K3 manual indicates that the Sub Receiver's AUX antenna must be well-isolated from the transmit antenna to avoid activating the sub's carrier carrier-operated relay. From a practical, real world standpoint, what is well isolated? Bill - N3KKM __ 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 __ 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
Re: [Elecraft] K3 Sub Receiver Antenna
Bill, Just an operating example, I have a short (well had) 330' beverage within 20 feet of my TX antenna for 160m. I have never had an issue with the relay tripping. I run LP or QRP, it may be an issue running HP, but I haven't heard any complaints from any of my friends on the Top Band. I don't use a relay like David does, but probably will in the future to detune my TX antenna. Not because of the second RX relay, but to minimize RX antenna pattern distortion. Probably the best thing is to use isolation transformers and current chokes, if in doubt or just to be safe. Those are relatively easy to implement. David's option is a bit more complex, but may be necessary in certain circumstances. The easiest thing to do is try it with your current setup, if it doesn't trip, then most likely you're well enough isolated for that particular issue. 73, Julius n2wn - Julius Fazekas N2WN Tennessee Contest Group http://www.k4ro.net/tcg/index.html Tennessee QSO Party http://www.tnqp.org/ Elecraft K2/100 #4455 Elecraft K3/100 #366 Elecraft K3#1875 -- View this message in context: http://elecraft.365791.n2.nabble.com/K3-Sub-Receiver-Antenna-tp5576061p5579047.html Sent from the [K3] 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
Re: [Elecraft] K3 Sub Receiver Antenna
Bill N3KKM wrote: The K3 manual indicates that the Sub Receiver's AUX antenna must be well-isolated from the transmit antenna to avoid activating the sub's carrier carrier-operated relay. From a practical, real world standpoint, what is well isolated? The easiest way to make sure is to check the RF power level from the aux antenna using a simple expendable diode detector, before connecting the antenna to the K3. The detector can be made in a couple of minutes from a 47 ohm resistor, a 1N4148 or similar diode and a 0.01uF ceramic capacitor. The rectified DC output is connected to a DMM, Any DC reading below about 1.0V will be fine. N4ZR has also published a passive protection circuit at: http://wiki.contesting.com/index.php/Basic_Receiver_Protection Next time I have the covers off the K3, I plan to install at least one +12V DC output with TX/RX switching, for use with preamps and protection relays. -- 73 from Ian GM3SEK http://www.ifwtech.co.uk/g3sek __ 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
Re: [Elecraft] K3 Sub Receiver Antenna
My arrangement has them within a few feet, so I will be using a high speed reed to remove and short the rx antenna. David G3UNA - Original Message - From: Bill N3KKM n3kk...@embarqmail.com To: elecraft@mailman.qth.net Sent: Monday, September 27, 2010 5:59 PM Subject: [Elecraft] K3 Sub Receiver Antenna The K3 manual indicates that the Sub Receiver's AUX antenna must be well-isolated from the transmit antenna to avoid activating the sub's carrier carrier-operated relay. From a practical, real world standpoint, what is well isolated? Bill - N3KKM __ 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 __ 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
Re: [Elecraft] K3 Sub Receiver Antenna
Bill, My answer is not a smart remark, but rather the truth - and that answer is Whatever it takes! There are so many variables that your question cannot be answered specifically for your location. Some of the variables are antenna polarization, physical distance, gain of the transmit antenna and its heading relative to the receive antenna. Trees, buildings and other objects that may shield the receive antenna from the transmit ant, proximity of feedlines, how much radiation is coming back on the feedline for each antenna, plus probably a host of other factors that I may not have thought of. You could make some tests using a simple pickup antenna and a field strength meter at your proposed location for the receiving antenna before placing it. Position the temporary pickup antenna for the least field strength. Unless you have a lot of freedom in the physical location of the receive antenna, the simple solution may be to switch in an attenuator for the subRX when transmitting. If the main and the sub are going to be on different bands, perhaps a bandpass filter would be a good solution - again, the real answer is Whatever it takes, and hopefully you can begin to understand why that is the only answer possible. 73, Don W3FPR On 9/27/2010 12:59 PM, Bill N3KKM wrote: The K3 manual indicates that the Sub Receiver's AUX antenna must be well-isolated from the transmit antenna to avoid activating the sub's carrier carrier-operated relay. From a practical, real world standpoint, what is well isolated? Bill - N3KKM __ 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
