[K3] Modification day for SN 01195
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[K3] Modification day for SN 01195
 
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I've been storing up a list of modifications I wanted to install in my
K3 (S/N 01195, July 2008) and managed finally to do them today. Due to the number (nine) and varying descriptions, purposes and locations in the rig, I tried to organize my thinking by putting them in a list, trying to see which ones I really need or want, how hard they might be to install, and which ones might be best done together due to being on the same board, etc. Some are documented in Elecraft's modification kits & parts area and some in the application notes area. I started by putting all of the PDFs into a directory of "official K3 modifications" so I could study them. The ones applicable to my K3's vintage were - K3AFMDKT --- Improve speaker & line out distortion and IMD K3DSPLPF --- Active audio LPF to reduce artifacts in the audio chain, add daughter board to DSP board K3IOBUFFKT -- Increase signal level at I.F. output by more than 10 dB AFOPMDKT -- Protect audio amp from short circuit or low impedance loads App Note -- Extreme signal RX protection mod App Note -- Protect against RF pickup at microphone connection by bypassing RF choke App Note -- Protect against chirp from synthesizer by increasing DDS signal driving the PLL App Note -- Improve immunity of RS232 and audio connections to RF by bypassing RF chokes App Note -- K3 SYN ALC mod. Assure enough drive when in high temperature environment Descriptions are my paraphrase and might not be totally accurate. Anyway, I did all of these today and made notes on the degree of difficulty and which ones might best work at the same time here - http://pages.suddenlink.net/wa5bdu/k3_mods.pdf If you have a similar vintage K3 and haven't kept up on mods, they might be of interest. None of them were really difficult for me, and the instructions were complete and accurate. I should say, I assembled my K3 from a kit, I do a lot of homebrewing but it's pretty ugly, and my vision wouldn't allow SMT work with just my bifocals, but with a 10x jeweler's loupe jammed into my good eye I do OK. I did all the mods today and didn't put anything back together until I'd finished them all. Doing it this way, it's important to bag or otherwise segregate all of the screws or other hardware from each cover or component removed and keep each piece in a separate place with its own hardware. I was most interested in the lowpass filter. I'm no golden ear, but possibly the power of suggestion made me think I heard some of the harshness others described. I found myself cranking the bandpass way down toward the low end. At least preliminarily, I think I do notice the improvement in the quality of the sound (I work CW) with the LPF installed. I'm pleased with Elecraft's way of publishing instructions and making mod kits available. Not to diss any other manufacturers, but most have a "no user serviceable parts inside" approach. 73- Nick, WA5BDU ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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http://www.elecraft.com/order_form_parts.htm K3DSPUPGD Improves low freq RX/TX audio response below 300 Hz, and adds a Low Pass Filter (LPF) that rolls off RX audio above 4 kHz. K3DSPLPF Small LPF add on SMD board for earlier K3 DSP boards that adds a Low Pass Filter to roll off RX audio above 4 kHz. This is already included on the K3DSPUPGD (above) I believe it's the DSP mod which improves audio response at the low end. The DSPLPF rolls off audio artifacts above 4 kHz. I use low pitch settings of 300-440 Hz and have considered both mods but haven't yet decided it's worthwhile. Without having two units (one with and one without) to compare, it's tough to know whether I'd notice any difference. 73, Bill |
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In reply to this post by Nick Kennedy
Thank you, I am in the same position and about to do the same thing, figuring out which mods go where etc - I might just be taking the whole rig apart!
Thanks for sharing that. 73 de M0XDF, K3 #174, P3 #108 The saddest aspect of life right now is that science gathers knowledge faster than society gathers wisdom. -Isaac Asimov, scientist and writer (1920-1992) On 26 Aug 2010, at 02:54, Nick-WA5BDU wrote: > I've been storing up a list of modifications I wanted to install in my > K3 (S/N 01195, July 2008) and managed finally to do them today. Due to > the number (nine) and varying descriptions, purposes and locations in > the rig, I tried to organize my thinking by putting them in a list, > trying to see which ones I really need or want, how hard they might be > to install, and which ones might be best done together due to being on > the same board, etc. Some are documented in Elecraft's modification > kits & parts area and some in the application notes area. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: [K3] Modification day for SN 01195
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In reply to this post by Bill W4ZV
Bill, > I use low pitch settings of 300-440 Hz and have considered both mods > but haven't yet decided it's worthwhile. Without having two units > (one with and one without) to compare, it's tough to know whether I'd > notice any difference. I added the LPF to my Rev.B DSP board and found that worthwhile. I can certainly notice the decrease in high frequency "garbage" in both speaker (Sony "bookshelf" speakers) and headphone (200/120 Ohm) audio. The only receive effect of the DSP upgrade is to decrease the LF corner frequency when using headphones. The corner (-3 dB point) frequency is dependent on the headphone impedance. Here is a comparison of the original 10 uF coupling capacitors and the new DSP board with 100 uF caps: Z Original Modified Notes --------------------------------------- 600 26 Hz 3 Hz 400 39 Hz 4 Hz 200 80 Hz 8 Hz Heil ProSet 150 101 Hz 10 Hz Senheiser PC-350 120 124 Hz 12 Hz Yamaha CM-500 64 221 Hz 22 Hz Senheiser HD-280 Pro 32 398 Hz 40 Hz Direct Sound EX-29 24 497 Hz 50 Hz Sony MDR-V150 16 663 Hz 66 Hz Etymotic ER6i, HF5 8 995 Hz 99 Hz Yaesu YH-55 The obvious conclusion is that the new DSP board reduces the corner frequency by a factor of 10 (as expected). Whether it matters to a given user depends on his headphone preference and the importance of LF response. With your EX-29, you might find the DSP replacement a plus; with my CM-500, I decided to pass on the DSP board replacement. 73, ... Joe, W4TV On 8/25/2010 10:17 PM, Bill W4ZV wrote: > > > Nick-WA5BDU wrote: >> >> K3DSPLPF --- Active audio LPF to reduce artifacts in the audio chain, >> add daughter board to DSP board >> >> <SNIP> >> >> I was most interested in the lowpass filter. I'm no golden ear, but >> possibly the power of suggestion made me think I heard some of the >> harshness others described. I found myself cranking the bandpass way >> down toward the low end. At least preliminarily, I think I do notice >> the improvement in the quality of the sound (I work CW) with the LPF >> installed. >> > > http://www.elecraft.com/order_form_parts.htm > > K3DSPUPGD Improves low freq RX/TX audio response below 300 Hz, and adds > a Low Pass Filter (LPF) that rolls off RX audio above 4 kHz. > > K3DSPLPF Small LPF add on SMD board for earlier K3 DSP boards that adds > a Low Pass Filter to roll off RX audio above 4 kHz. This is already included > on the K3DSPUPGD (above) > > I believe it's the DSP mod which improves audio response at the low end. > The DSPLPF rolls off audio artifacts above 4 kHz. > > I use low pitch settings of 300-440 Hz and have considered both mods but > haven't yet decided it's worthwhile. Without having two units (one with and > one without) to compare, it's tough to know whether I'd notice any > difference. > > 73, Bill > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Nick Kennedy
Thanks for the helpful info, Nick. I have an unmodified K3 of the same
vintage and just yesterday was trying to decide what order to perform the mods. A couple of mods I didn't notice on your list that might be applicable are the Systhesizer Stiffener Plate and the 12v Sense mod. I'll skip the synth plate as that doesn't seem to be a problem with my K3 (I have attached a baffle to the back of my speaker). As for the 12v sense, I haven't had any problems but seems like I might as well install it. 73, Drew AF2Z On Wed, 25 Aug 2010 20:54:32 -0500, Nick, WA5BDU wrote: > I've been storing up a list of modifications I wanted to install in my >K3 (S/N 01195, July 2008) and managed finally to do them today. Due to >the number (nine) and varying descriptions, purposes and locations in >the rig, I tried to organize my thinking by putting them in a list, >trying to see which ones I really need or want, how hard they might be >to install, and which ones might be best done together due to being on >the same board, etc. Some are documented in Elecraft's modification >kits & parts area and some in the application notes area. > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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