Arie, As Wayne explained, the K3 has plenty of audio gain, and yes, the audio gain can be advanced sufficiently to hear the internal receiver noise, and even hear it as a mild 'roaring' noise. Gains 'all to the right' is not a good way to compare two receivers - ideally one would have to compare the audio at a level where the same signal produces the same amount of audio for both receivers. You can achieve that by using a steady signal source (a signal generator is ideal) that produces a signal level near S-9 and then connect the FT1kMP audio to a computer running an audio spectrum analyzer application (like Spectrogram) which will display the signal amplitude. Do the same with the K3 and set the AF Gain to produce the same signal amplitude. You will then have the same overall gain set for both receivers. You are attempting to compare the receiver internal noise level and not the receiver gain, so for a valid comparison, the gain of both receivers must be made the same for the test.
You indicated that the noise increased on your K2 when you disconnected the antenna. AGC could do that, or too high a setting of the AF Gain. If you have any signals in the receiver passband when you have the antenna connected, the AGC would have held the receiver gain down (how much depends on your AGC SLP and TH menu settings) - then when the antenna is removed, the K3 will go to full gain, and you will be hearing the internal noise at full gain. Actually noise evaluation should be done with the AGC off so its action will not influence the test outcome. My K3 has enough audio gain that I can just barely hear the internal receiver noise with the AF Gain set at about the 8:30 position.on the internal speaker if the menu AG Gain parameter is set to HI, and about the 11:30 position if AG Gain is set to LO. With a dummy load connected (or the antenna disconnected), if I leave the RF Gain at maximum and set the AF Gain to the point where I can barely hear the receiver noise, then connect an antenna, the noise level always increases - this is the reverse of your test, but it should be just as valid. The only way I can get my K3 to have almmost as much noise with the antenna removed as it has with the antenna connected is to set the AGC Threshold to its minimum value (002). My AGC Threshold is normally set at 008. As a side-point, I set my AGC SLP at 002 because that produces a response similar to that of the K2 which I liked - weak signals sound weaker, strong signals stronger and I can judge that without reference to the S-meter. If you wish to try some other tests, let me know and I will try to help. 73, Don W3FPR Arie Kleingeld PA3A wrote: > Let me throw in a penny please. > > Just for comparison: > FT1kMP : all controls full gain (except AF of course), antenna connected. > Then disconnect antenna and listen: nearly no audio, only the receiver > noise. > > K3: do the same. Difference is that when I disconnect the antenna, the noise > coming from the speaker is much louder! So the receiver noise is much > louder? I thought that that might come from the dsp design. (I think that > that is what Don meant) > > I am open for enlightenment. > > 73 > Arie > > ______________________________________________________________ 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
