K2 and FSK
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Hi
Is there anyone who know articles or ideas about K2 FSK mod ? 73 de aki, ja1nlx [hidden email] http://www.asahi-net.or.jp/~yy7a-ysd/ _______________________________________________ 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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aki, ja1nlx, asked:
Is there anyone who know articles or ideas about K2 FSK mod ? ------------------------------------ Most rigs today do not produce true FSK. That is, they don't shift the carrier frequency. Instead, they operate in Single Sideband mode and an external "frequency shift keyer" inputs changing audio tones into the mic connector. The RF output from the rig is then the suppressed carrier frequency + or - the audio tone, depending upon which sideband is in use. As long as the rig is set up properly with adequate sideband and carrier suppression, it's almost indistinguishable from true FSK. The tone generation is commonly done with a computer sound card, like many other digital modes today. Many hams have developed interfaces for use between their computers and their rigs. These interfaces are designed to provide the proper audio levels and to avoid ground loops that can cause hum or other problems in the system. Many have been published on the internet. Among them are S56AL's nice web pages at: http://lea.hamradio.si/~s57nan/ham_radio/ which features schematics of some interface units at: http://lea.hamradio.si/~s57nan/ham_radio/sb_intf/sb_intf.html These aren't specifically designed for use with the K2, but the basic principle is directly applicable to a K2 equipped with the KSB2 SSB board. 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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Hi Ron and others,
As I very much like to do EME and MS on 144 MHz my RF-power there is higher than average to say the least hi! So as to reduce chances for LFD etc, I decided that I should use FSK CW. It had to be FSK without phasejumps, so SSB-FSK was found to be not suitable. At the time I decided this, there was no commercial product on the market (and today there still is not) so I had to build something myself. That way my current 2m transceiver was conceived and it is still in use. It now uses a DDS and by manipulating the DDS databus, It makes realtime FSK, virtually without phase-jumps. The neighbours only hear a slight click when I switch the TX on/off. Also since the introduction of WSJT, a convector (developed by PA3BIY) was taken in use, that converts the tones of WSJT to data for the DDS. I have a K2 in use as a secondary transceiver on 144 with the DEM 144-28 ECK built in. I also use this rig as IF for microwave, very recommended I must say! So if the K2 could ever make real FSK, I would be very pleased! But it would probably take a significant hardware modification and software development for just a small group of people, so I guess that the developers at Elecraft will probably think they have something better to do hi! Or?!... 73, Dick PA2DW K2/DEM 144-28ECK KX1 _______________________________________________ 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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Dick PA2DW wrote:
"...if the K2 could ever make real FSK, I would be very pleased! But it would probably take a significant hardware modification and software development for just a small group of people, so I guess that the developers at Elecraft will probably think they have something better to do hi! Or?!..." -------------------------------- As I was answering Aki's question I was thinking that the K2 already does "true" FSK, but not at data keying rates. The PLL local oscillator and BFO frequencies are changed by the controller as needed to maintain the dial accuracy when the sidetone pitch is change in the MENU. I'm not sure about the phase issues, but it had me wondering if it were possible to provide an external keying input that would toggle between two "sidetone" frequencies during transmit in CW mode. Perhaps just a tuning input to the BFO would do the trick, since it's already a VCO and it is part of the transmit signal chain. However, maintaining phase while changing frequencies is a different story. For that, how about an external DDS with the necessary keying circuitry such as you described used as an external transmit BFO for the K2? Your observation about the relatively small number of users compared to the whole K2 population out there is exactly why Wayne and Eric had always encouraged experimentation with the Elecraft rigs, and even offer a helping hand when they can. 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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