> If you are a contester please respond off list. I chose to reply to the list because this is a topic of interest to many, whether contesting or not.
> What AGC > settings are you using? In sprint last night I used the K-3 > (first real contest) and I was less than thrilled with rx > performance. Close by stations seemed to overload the rx. > Something I didnt have with my MKV with the inrad mods and > filters. Been fiddling with the settings but obviously dont > have it right. All my operating is contesting and I've used two K3s for a year now. At home, there are several local contesters just a few miles line-of-sight off the back lobes of my Yagis. At 1.5 KW they saturate my S-meters. Still, they are unnoticeable when outside my filters and I'm usually run the default AGC settings. Most people have reported just the opposite comparison between the MKV and K3, i.e., they prefer the K3 RX in contest or crowded band conditions with strong signals nearby. The PREamp has more impact on RX overload than the AGC in most cases. On the low bands, you may even need to engage the ATTenuator. Don't make the AGC do all the work by slamming it with too much signal strength. Certainly, you can optimize the AGC for different conditions by changing the threshold and slope. For many it is a matter of personal preference more than an absolute "correct" setting. You will probably want higher thresholds on the lower bands due to the noise level. The slope is a trade-off between reducing gain for strong signals and still having discrimination between different signal strengths. If you keep the front-end tamed down with appropriate PRE and ATT engagements, then you will find the AGC gives you fine control over the range of signal strengths rather than relying on it alone for dealing with the very strong signals. > filters in rig 2.8, 1.8 and 250 Remember your "250" filter is really 370 Hz at the -6 dB points, so you might have it engage at DSP bandwidth of 350 or 300 Hz. But even at 350, the cascade effect will produce an overall bandwidth of less than 300 Hz, which is a bit narrow for CW contesting, IMO. At DSP WIDTHs of 400-500 Hz, your roofing filter will be the 1.8 kHz, if you have it configured "normally", so that doesn't give you IMD protection for the DSP with very strong signals located between your DSP and crystal filter widths. (I should point out that some K3 ops don't subscribe to the K3 design that deploys the crystal filters as roofing filters that are set wider than the DSP WIDTHs to protect the DSP. Instead they prefer the passband shape of the crystal filter and effectively eliminate the DSP filter by configuring their K3 filtering to have the crystal filter engage at DSP bandwidths GREATER than the crystal filter. Until the DSP WIDTH is reduced to well within the crystal filter bandwidth, the crystal filter is dominating the passband shape and filtering. Of course, the DSP will still provide steeper skirts at a point well below the passband.) 73, Ed - W0YK P.S. Thanks for the Sprint Qs! _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
