++++++++++++++ Date: Fri, 29 Nov 2002 19:57:00 +0000 From: pjhend at ameritech.net To: elecraft at mailman.qth.net Subject: Re: [Elecraft] K2 with an outboard DSP I occasionally use a DSP-59+ and Motorola HSN4039A with my K2 with very good results - keep in mind that in most instances, it is not necessary at all. I like the 59+ just a little better than the ClearSpeech DSP (which did a nice job as well). I also use a DSP-9 with my Kenwood TS-930S with good results. Picked up both of the DSP's "used" for very fair prices. Just my limited experiences.... 73 Paul k4wtf at ENTERZONE.NET wrote: > On Fri, 29 Nov 2002, Bob Nielsen wrote: > > > > Good audio DSPs can be had rather cheaply these days, the Timewave-59+ and > > > NIR-12 are going for $100 to $125 used. They provide most, if not all the > > > functionality that one needs. The advantages of implementing the DSP in the > > > last - low frequency IF does not seem to me to be worth the price of a new > > > rig. I understand the advantages of having filtering in the AGC loop, but > > > implementing it in the last IF brings up all sorts of issues with what > > > happens to the strong signals in previously filtering. > > > > > > Just my $0.02 worth. - Dr. Megacycle KK6MC/5 > > > > Good point. Perhaps someone could report their experiences with the K2 > > and an outboard audio DSP unit. > > > > Bob, N7XY > > I've used my ClearSpeech DSP with my K2. It works wonderful. When the > signal is down in the noise and barely audible, switching to DSP mode will > often make it sound like the person is sitting right beside you. > > 73 de John - K4WTF > K2/100 #2490 +++++++++++++++ From: "Mike McCoy" To: Subject: Re: [Elecraft] Comparing the K2 to other RIGs Date: Sat, 30 Nov 2002 08:12:38 -0600 > > > > Good audio DSPs can be had rather cheaply these days, the Timewave-59+ and > > NIR-12 are going for $100 to $125 used. They provide most, if not all the > > functionality that one needs. The advantages of implementing the DSP in the > > last - low frequency IF does not seem to me to be worth the price of a new > > rig. I understand the advantages of having filtering in the AGC loop, but > > implementing it in the last IF brings up all sorts of issues with what > > happens to the strong signals in previously filtering. > > > > Just my $0.02 worth. - Dr. Megacycle KK6MC/5 > > Good point. Perhaps someone could report their experiences with the K2 > and an outboard audio DSP unit. > I use a Timewave DSP-599ZX in conjunction with my K2. As good as the K2 is on its own the Timewave puts it in whole new league (for the better). I like how it is in essence three distinctly seperate DSP units (Voice, CW & DATA), each with their own unique features for each mode. And you can operate two seperate rigs off one 599ZX (discrete A & B channels), so it's almost like having 6 DSP units in one box. And oh yea, it has an integral FSK signal detector/generator & 'rigblaster' interface. Hit the 'random' button and the QRM basically goes away (like a clearspeech?). Hit the 'tone' button and that annoying heterodyne is automagically gone. And the audio doesn't sound like it's coming out of a 'tin-can' that is usually associated with outboard audio filters There is no way I could cover all the features of the 599ZX. Just go to the Timewave website for details. I know I sound like a Timewave ad but I actually like it so much I have two, one for my K2 and one for my Icom 751A. 73, Mike K5PU +++++++++++++++++ From: "robert parker" To: "'Mike McCoy'" , Date: Sat, 30 Nov 2002 09:36:52 -0500 Subject: [Elecraft] Using DSP with the K2 I sometimes use an MFJ-784B DSP unit with my K2. It is used only when Conditions are very poor and only with SSB. No need for it ever in CW. The DSP does work well but sometimes on the bands nothing works and even those multi kilobuck transceivers fail. Generally there is no need for DSP with the K2. The low noise floor and great user programmable filtering works very well. Also I think the audio filter (KAF2) is a must and will suppress much of the noise in addition to the filtering. DSP will leave behind artifacts in the audio stream which can become fatiguing to listen to. It's almost as bad as the noise it was used to suppress in some cases. Cheers, Robert VE3RPF +++++++++++++ From: "Dave White" To: Date: Sat, 30 Nov 2002 10:08:28 -0700 Subject: [Elecraft] DSP and the K2 (was Comparing the K2 to other RIGs) Bob, N7XY asked for more comments regarding using an outboard DSP with the K2. I have used two such units; the TimeWave 599ZX (latest firmware) and the ClearSpeech Base II. My K2 is fully loaded, including the K2 audio filter (KAF2), and all of the "latest" mods from the reflector (at least on the receiver end). My operation is strictly SSB or digital modes. As background, I am a big fan of DSPs, especially when I used them with my previous rigs (assorted "high end" units). When used with the K2, I have tried both units using the external speaker output from the K2, as well as tapping the 599ZX into the audio cct after the KAF2 audio filter (to provide more constant audio level feed -- I built a special interface board for this to convert the signal from "balanced feed to unbalanced" and back again -- I was careful to match audio levels and impedances so as not to overdrive the K2 final audio amp). My experience with a DSP on the K2 have been somewhat disappointing (ie: the improvement in audio and reduction in noise was less dramatic than anticipated). After months of careful listening, I came to the conclusion that the receiver of the K2 was quieter than previous rigs and hence DSP filtering improvements were marginal. I did not use the bandwidth reduction controls on the 599ZX very much, as I always seemed to be able to reduce adjacent channel interference using a combination of IF filter adjustments on the K2 (the preferred method). The one major advantage to either DSP has been the automatic heterodyne reduction feature, something the K2 lacks. Both DSP units perform this function well. At this point I prefer the ClearSpeech Base II for it's simple operation and lower cost. On the noise reduction side, the time constant averaging feature of the ClearSpeech algorithms take longer to respond than the 599ZX, but the effect is not objectionable, and simple rewiring of the input feed cct to the ClearSpeech may eliminate some of this effect; the ClearSpeech On/Off switch turns the unit off as well as bypassing the audio -- my thought is to retain power and audio feed to the input while switching the audio output only, hence leaving the noise reduction cct active and the noise reduction algorithms "up to date". I also found the ClearSpeech noise reduction less aggressive than the TimeWave, which, in my opinion, was better suited to the K2's lower receiver noise (and yes, I know the TimeWave noise reduction effect can be adjusted). Another advantage for the more adventurous is the ability to mount the ClearSpeech board into an EC-2 with a pair of K2 speakers to make a matching DSP'd external speaker enclosure. I prefer to have a front firing speaker in my shack. This is my next project. My comments on the KAF2 echo those of others on the reflector; I find the overall effect of KAF2 cct in reducing high frequency noise an advantage. However, I make limited use of the other audio filter functions as they are designed primarily for CW mode. They have proved an advantage on occasion with digital modes; it depends on the nature of the interference. Has anyone experimented with altering the characteristics of the KAF2 filters to make them more suitable for broadband (SSB) work? My filter design skills are weak. Anyway, I now have a TimeWave 599ZX for sale ;-) As always, the experiences of others may be different depending on their operating preferences and opinion as to what constitutes "good received audio". Regards Dave White VE6DRW K2 S/N 2171 +++++++++++++++++