RE: [Elecraft] K2 Noise Blanker Slot as Additional IF Amplifier Stage
Hi Dick, The variable crystal filters in the K2 are very good. In fact the best I have ever used. As Don says, unless you have a bad component, crystal filtering should be excellent down to about 250 Hz, and the DSP down to 100 Hz before you get a bit of attenuation of signal. You can even boost the volume a bit in the DSP adjustments. I originally had similar problems to you when I first built the rig in 1999. Now I use MixW to check the filters visually. You can also use Spectrogram. Pictures don't lie. I have some MixW screens shots on my website here. I think it would be hard to get these kind of results with most other ham transceivers. http://users.ev1.net/~spituch/Steve's%20Page/Radio/RTTY/RTTY.html From the photos alone the performance of the filters look phenomenal. If you adjust the filters while looking at the MixW screen you can get instant feedback on the adustments you are making and easily adjust the filters perfectly. Centering the filters this way is a snap. One of the reasons for the great popularity of the K2 is that you don't need to add any filters. Regards, Steve, W2MY -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.405 / Virus Database: 268.10.9/416 - Release Date: 8/10/2006 ___ 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
[Elecraft] K2 Noise Blanker Slot as Additional IF Amplifier Stage
Has anyone thought of, or tried modifying the K2 Noise Blanker to be an additional K2 IF amplifier stage? My problem is that when I really, really need the crystal filter, I am trying to copy a very weak (but readable) CW signal with adjacent S-9 QRM. When I switch in tighter than about 1200 Hz of crystal filtering, I tend to lose the target signal due to filter loss. ( Losing the target signal is not because the BFOs are not properly calibrated). When I use just the DSP filter to block the adjacent S-9 QRM, then I still lose the target DX due to AGC pumping (without the IF roofing filter). I'd really like some additional IF gain to compensate for the crystal filter loss. I would try using the Noise Blanker's U1, MC1350, as the added IF stage, and use U3, the Controller's decoded program lines to adjust U1's AGC input for front panel gain control. I could use P1's pin 8, 8R, as power for the MC1350 so that it's only active on receive. Any feedback would be appreciated. 73, Dick, AD7AF Dick and Marty Lemke PO Box 1038 Ocean Park, WA 98640 Tel. 360-665-2438 www.lemkestudios.com ___ 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
RE: [Elecraft] K2 Noise Blanker Slot as Additional IF Amplifier Stage
Dick, Not an IF amplifier stage, but an added IF filter - check out http://homepages.nildram.co.uk/%7Ebaker/K2_Overview.html to see if that might address your stated needs. If you have filter loss at bandwidths less than 1200 Hz, then I would conclude that you have something wrong with your filter - the filter typically does not show attenuation until the bandpass is reduced to less than 200 Hz. If you are certain your BFO frequencies are correct (the filter peak is centered on your sidetone pitch), you should not experience attenuation at reasonable filter widths - if you do, I would suspect that you have a bad crystal in the filter. 73, Don W3FPR -Original Message- Has anyone thought of, or tried modifying the K2 Noise Blanker to be an additional K2 IF amplifier stage? My problem is that when I really, really need the crystal filter, I am trying to copy a very weak (but readable) CW signal with adjacent S-9 QRM. When I switch in tighter than about 1200 Hz of crystal filtering, I tend to lose the target signal due to filter loss. ( Losing the target signal is not because the BFOs are not properly calibrated). When I use just the DSP filter to block the adjacent S-9 QRM, then I still lose the target DX due to AGC pumping (without the IF roofing filter). I'd really like some additional IF gain to compensate for the crystal filter loss. I would try using the Noise Blanker's U1, MC1350, as the added IF stage, and use U3, the Controller's decoded program lines to adjust U1's AGC input for front panel gain control. I could use P1's pin 8, 8R, as power for the MC1350 so that it's only active on receive. ___ 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
