K2 vs. K1 - Info please.
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Yea, I know, we've discussed this before. I'm not going to ask a
general question because it is too easy to get into an apples to oranges comparison. But I've had the K1 for a bit now and have become familiar with it's performance and operation. Now I have a better basis for understanding the K2. So on to the questions. 1. How do the IF filters in the K2 compare to the audio filters in the K1. I assume they provide more selectivity and greater stop-band rejection. I also assume the multiple IF stage filters in my Omni will provide even greater selectivity. 2. How does the RX noise level compare between the K2 and K1. My K1 is a quieter rig than the more complex Omni V that it sits on. It is just nicer to listen to. If the K2 is similar to the K1 it would be a very sweet rig. 3. AGC - Does the K2 have multiple AGC rates (fast & slow?)? 4. Tuning rates. K1 tunes very quickly. Similar to analog rigs from the 80's. I assume the K2 tunes slower, yes? 5. Knob wobbliness. The knobs on my K1 are just a bit wobbly. The pots are tight on the PCB but the shafts have some play. Is this the case with the K2? I assume it uses the same pots and has the same feel. 6. SWR protection of the finals. Are the finals SWR protected in some way? What I'm thinking right now is I'll sell the Omni V and the K1 and buy a K2/100 with SSB. I'm not a builder so I'd be looking for a very late SN used rig or may just buy new and have a pro build it for me. Hmmm, lots to think about ... think think think ... - Keith KD1E - _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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>1. How do the IF filters in the K2 compare to the audio filters in the K1.
I can't address the K2, but the variable bandpass filtering in the K1 takes place in the IF crystal filter network. The audio filtering is fixed. >5. Knob wobbliness. The knobs on my K1 are just a bit wobbly. Early K1 kits were provided with AF and RIT pots whose plastic shaft did not have much support, so there was a lot of wobble. You can solve that by installing replacements from Elecraft. The parts now being supplied (since 2002??) have significantly greater shaft support and feel much much better. I'd assume that if you bought an early used K2, it would be likely that the earlier style pots would be found on it as well. 73, Mike / KK5F _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
RE: K2 vs. K1 - Info please.
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In reply to this post by Darwin, Keith
Keith KD1E asked:
1. How do the IF filters in the K2 compare to the audio filters in the K1. I assume they provide more selectivity and greater stop-band rejection. I also assume the multiple IF stage filters in my Omni will provide even greater selectivity. 2. How does the RX noise level compare between the K2 and K1. My K1 is a quieter rig than the more complex Omni V that it sits on. It is just nicer to listen to. If the K2 is similar to the K1 it would be a very sweet rig. 3. AGC - Does the K2 have multiple AGC rates (fast & slow?)? 4. Tuning rates. K1 tunes very quickly. Similar to analog rigs from the 80's. I assume the K2 tunes slower, yes? 5. Knob wobbliness. The knobs on my K1 are just a bit wobbly. The pots are tight on the PCB but the shafts have some play. Is this the case with the K2? I assume it uses the same pots and has the same feel. 6. SWR protection of the finals. Are the finals SWR protected in some way? ---------------------------------------------------------------------------- ---- Keith, I don't own a K1 so I can't speak to the K1-specific issues. The K2 is a completely different rig from the K1, mechanically and electrically. Regarding the AGC, the K1 uses audio-derived AGC while the K2 has an I.F.-derived AGC. The I.F.-derived AGC is inherently faster to take hold than audio AGC, producing smoother action on the "attack". That's a basic limitation of any audio-derived AGC. It takes several cycles of rectified signal to build up the voltage needed to control the gain. Several cycles of signal happen much, much more quickly at the intermediate frequency than they do at an audio frequency, so the control voltage is available much more quickly in an I.F-derived system. Yes, the K2's AGC has a fast and slow mode. And it has an "off" mode, which I use a lot when tuning around<G>. Although I will say that for this "AGC-hater" I find the K2's AGC no problem at all. I often turn AGC off because I don't want the receiver turning up the gain between signals. I prefer to hear the background stay constant as I tune with the signals standing out above it at various levels according to their strengths, rather than having everything adjusted to about the same sound level. If I want to dig for a weak signal down near or in the noise, I turn up the gain <G>. The K2's tuning rates are variable in three steps from very fast, about 100 kHz per revolution, to about 6 kHz per revolution, and on down to about 1 kHz per revolution. The K2's tuning is controlled by an optical encoder, not a pot, so the feel is very smooth and precise. The readout is in 10 Hz steps but, thanks to a unique phase-locked loop (PLL) design used in the local oscillator, the tuning is smooth with no 'steps'. The PLL local oscillator is also very quiet electrically, avoiding the phase noise usually associated with many PLL local oscillators that shows up as excess noise indistinguishable from normal background QRN. The K2 does this by using a PLL that tunes in about 5 kHz "steps" and then varies the PLL reference oscillator's frequency to tune smoothly in between those steps. So the tuning has the true smooth feel and spectral purity of an excellent "analog" oscillator with the accuracy and stability of a good PLL. The dial reads out in 10 Hz steps. The logic design limits the absolute accuracy to about 20 or 30 Hz, although it's not unusual for the K2 display to be within 10 Hz of the actual frequency. I can't speak in any great detail about the protection circuits in the finals for either the KPA100 or the K2. I know they both withstand repeated transmits into an open load at full power setting without harm. The finals in both the basic K2 and the KPA100 are very conservatively rated, handling rather severe overloads and operating stresses without trouble. Ron AC7AC _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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