[Elecraft] RF gain, preamp and attenuator
I am a new owner of a K3 and also run an Orion 2 which is IMHO a fine rig. I like its larger size and remote pod for use in contests. Put this aside I need to know how to drive the K3 but am influenced by the O2. For the O2 I keep attenuation off, preamp on and ride the rf gain and I do this for all bands on CW including 160 M. Sometimes for contest work I throw in some attenuation though it does not seem to be required. Is it the consensus that for the K3 a similar approach is used or am I right in gathering that many of you disable the preamp and introduce attenuation as well as throttling rf gain? Both rigs allow many options and learning to configure them for ones style of operation is critical. I helped a friend with an O2 who was having a horrible time until we went through the menus together and then he enjoyed the sun. I hope not to have too steep a learning curve and am grateful for your guidance. Thanks! 73 Doug EI2CN __ 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] RF gain, preamp and attenuator
I am a new owner of a K3 and also run an Orion 2 which is IMHO a fine rig. I like its larger size and remote pod for use in contests. Put this aside I need to know how to drive the K3 but am influenced by the O2. For the O2 I keep attenuation off, preamp on and ride the rf gain and I do this for all bands on CW including 160 M. Sometimes for contest work I throw in some attenuation though it does not seem to be required. Is it the consensus that for the K3 a similar approach is used or am I right in gathering that many of you disable the preamp and introduce attenuation as well as throttling rf gain? EI2CN is a very familiar call on 160...most recently in the ARRL DX CW! I was an original Orion owner for 4 years before getting the K3 so here are some comments which apply to both. First, it's important to carefully place any receiver's noise floor just below the band noise being presented by your antenna. There is no hard and fast rule for this because it will depend on the band (low bands being noisier), your antenna's gain and the gain of your receiver. If you do this properly, you will be maximizing the dynamic range of your receiver above the noise floor and not wasting part of it by being below the noise floor. Here's a graphic example, where A is the antenna noise, and 1 = ATT, 2 = neither ATT/PRE, 3 = PRE: 1: 00 2:00 3: 00 A:N In case 1, you have too much attenuation so you will miss the weak signal N. In case 2, the receiver is maximizing its dynamic range above N. In case 3, You have too much gain (i.e. noise floor is below N) and are wasting some of your RX's potential dynamic range above N. The simplest way to properly set ATT/OFF/PRE is to apply your antenna (with no signals except band noise) to your RX with RF GAIN max CW, and listen to see if you can hear any band noise increase in the following order: first with ATT on, then both ATT/PRE off, then with PRE on. You should stop when you can just detect an increase in band noise when the antenna is applied. Normally this will mean ATT on for the low bands because the atmospheric noise floor is much higher than higher bands **but** it will also depend on the antenna you are using. If you have a very lossy RX antenna like a Flag/Pennant, you very well may need PRE on. If you have a large vertical, you will probably need ATT on. So the best setting will depend both on the level of band noise and your antenna gain. Once you have ATT/PRE set properly, then you should back off RF GAIN (CCW direction) until you see band noise stop flickering the S-Meter. That is, set RF GAIN so it is just at the ambient noise level being shown on the meter. For the K3, I usually have AF GAIN set at about 9 o'clock and RF GAIN will vary from 3 o-clock to noon...depending on the ambient noise level. I also often use diversity with two very different antennas. My 160 TX antenna is a 3-element parasitic vertical with approximately +5 dBi gain and my RX Beverages have approximately -10 dBi gain. I want to normalize the signals into the K3 so I set ATT on for the TX antenna path on Main and PRE on for the RX antenna path on Sub. Then I can keep both RF GAIN knobs at approximately the same settings. I also use the SUB RX Audio Gain fader control so both channels are controlled by the inside AG Gain knob. I hope this helps and that my little graphic is not too distorted to get the general idea. 73, Bill W4ZV -- View this message in context: http://n2.nabble.com/RF-gain%2C-preamp-and-attenuator-tp2548489p2548976.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
Re: [Elecraft] RF gain, preamp and attenuator
btipp...@alum.mit.edu wrote: The simplest way to properly set ATT/OFF/PRE is to apply your antenna (with no signals except band noise) to your RX with RF GAIN max CW, and listen to see if you can hear any band noise increase in the following order: first with ATT on, then both ATT/PRE off, then with PRE on. Thanks, Bill, for the very nice write up. I'd like to mention that on the K2 - and I imagine on a K3 that I hope to own one day soon! - you can cycle through all four combinations of ATT/PRE on/off if you use software. I wrote a bare bones (i.e., ugly!) C program that performs some k2 cmds. I originally wrote it to first do a low power tune and then a high power tune, but have added more functions as time went on. Eventually I added a 'level' cmd so that I can choose between RF gains of +14, +4, 0, and -10 dB using the various att/pre combos. Nothing major, but maybe lets you further fine tune your rf gain settings. 73, Mike ab3ap __ 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] RF gain, preamp and attenuator
My settings: 10, 15 preamp, no attenuator 20 preamp sometimes, no attenuator 40 no preamp, sometimes attenuator 80, 160 attenuator, no preamp Dave Hachadorian, K6LL Yuma, AZ - Original Message - From: Doug Turnbull turnb...@net1.ie To: elecraft@mailman.qth.net Sent: Saturday, March 28, 2009 9:28 AM Subject: [Elecraft] RF gain, preamp and attenuator I am a new owner of a K3 and also run an Orion 2 which is IMHO a fine rig. I like its larger size and remote pod for use in contests. Put this aside I need to know how to drive the K3 but am influenced by the O2. For the O2 I keep attenuation off, preamp on and ride the rf gain and I do this for all bands on CW including 160 M. Sometimes for contest work I throw in some attenuation though it does not seem to be required. Is it the consensus that for the K3 a similar approach is used or am I right in gathering that many of you disable the preamp and introduce attenuation as well as throttling rf gain? Both rigs allow many options and learning to configure them for ones style of operation is critical. I helped a friend with an O2 who was having a horrible time until we went through the menus together and then he enjoyed the sun. I hope not to have too steep a learning curve and am grateful for your guidance. Thanks! 73 Doug EI2CN __ 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
