I have been very pleased with the 2.7kHz, 1.8kHz, and 500Hz filters. Even in a multi transmitter environment. The DSP is excellent for eliminating adjoining QRM.
Nothing works for eliminating adjacent wide transmitter splatter and key clicks falling into ones receiver bandwidth. 73 Bob, K4TAX Sent from my iPhone > On Dec 26, 2025, at 11:02 AM, [email protected] wrote: > > Send Elecraft mailing list submissions to > [email protected] > > To subscribe or unsubscribe via the World Wide Web, visit > http://mailman.qth.net/mailman/listinfo/elecraft > or, via email, send a message with subject or body 'help' to > [email protected] > > You can reach the person managing the list at > [email protected] > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of Elecraft digest..." > > > Today's Topics: > > 1. Re: Advice on Additional Roofing Filters for K3 (Fred Jensen) > 2. FOR SALE - K4 (Hunsdon Cary III) > 3. Re: K2 Receiver dead (Mike Furrey) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Thu, 25 Dec 2025 21:32:15 +0000 > From: "Fred Jensen" <[email protected]> > To: "Henry Pollock - K4TMC" <[email protected]>, > "[email protected]" <[email protected]> > Cc: Elecraft Reflector <[email protected]> > Subject: Re: [Elecraft] Advice on Additional Roofing Filters for K3 > Message-ID: <[email protected]> > Content-Type: text/plain; charset=utf-8; format=flowed > > It might be useful to remember: Roofing filters at the front end of the > K3's 8.1 MHz 1st IF protect the ADC from overload by [very] strong > signals adjacent to your QRG. If you are not plagued by such very > strong signals ... usually from local-ish stations ... roofers are a lot > like snowflakes, "seen one, you've seen them all." So long as the > filter is wide enough for the signal bandwidth and the integrated > spectral power centered at 15 kHz does not overload the ADC, the > bandwidth limiting/positioning provided by the DSP will do it all for > you. > > I have two roofers in my very aged K3, narrow and wide. They're the > ones that came with it [500 Hz and 2.7 kHz? Don't remember]. I don't > seem to have any locals here that overload the ADC, and on CW, there's > no discernible difference between them. My K3 hasn't seen a phone > signal in a long time. ? > > If you are plagued by a signal with lots of in-band phase noise [I was > in a previous QTH], filtering will improve the SNR at the ADC some, but > your only real recourse is to convince the op to buy a new phase-free > radio. > > 73, > > Fred ["Skip"] K6DGW > Sparks NV DM09dn > Washoe County > > > > ------ Original Message ------ >> From "Henry Pollock - K4TMC via Elecraft" <[email protected]> > To [email protected] > Cc [email protected] > Date 12/24/2025 1:21:56 PM > Subject Re: [Elecraft] Advice on Additional Roofing Filters for K3 > >> Tom, >> >> I have the 1.8 filter in my old K3 #98 and have found over the years that I >> almost never use it. The DSP Width and Shift controls with the stock 2.7 >> filter have been adequate for my needs in all SSB contest conditions when >> using fast AGC. So, if I wanted a narrower filter for SSB, then the 2.1 >> would be the only one I would consider. >> >> 73, >> Henry - K4TMC >> >>> On Wed, Dec 24, 2025 at 2:10?PM Jim Brown via Elecraft < >>> [email protected]> wrote: >>> >>> On 12/24/2025 8:43 AM, Tom Bowles via Elecraft wrote: >>>> I'm considering adding a 1.8 kHz for SSB and a 250 Hz for CW, but I've >>> read that the 250 Hz filter often measures wider in practice (around >>> 330-350 Hz) and may not be as sharp as expected. Has anyone experienced >>> this, and would you recommend it, or suggest alternatives like the 200 Hz >>> or 400 Hz instead? >>> >>> First, these are ROOFING filters to protect the DSP IF from overload >>> from very strong nearby stations. It is that DSP that sets the IF >>> bandwidth. I'm a serious contester, and have used K3s since 2008. The >>> 250 Hz 8-pole filter is great for CW. I found the 1.8 kHz filter too >>> narrow for SSB, and prefer the 2.1 kHz filter. If you work RTTY, the 2.8 >>> kHz filter has much better response than the stock 2.7 kHz filter, which >>> greatly reduces the incidental AM on transmit with RTTY. If you don't do >>> RTTY, it doesn't matter. >>> >>> 73, Jim K9YC >>> ______________________________________________________________ >>> Elecraft mailing list >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>> Help: http://mailman.qth.net/mmfaq.htm >>> Post: mailto:[email protected] >>> >>> This list hosted by: http://www.qsl.net >>> Please help support this email list: http://www.qsl.net/donate.html >>> Message delivered to [email protected] >>> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[email protected] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [email protected] > > ------------------------------ > > Message: 2 > Date: Fri, 26 Dec 2025 08:10:39 -0500 > From: Hunsdon Cary III <[email protected]> > To: Elecraft Mailman <[email protected]> > Subject: [Elecraft] FOR SALE - K4 > Message-ID: <[email protected]> > Content-Type: text/plain; charset=utf-8 > >>> Subject: FOR SALE - K4 >>> >>> ?K4 serial #1097 - 100 watt w/ antenna tuner, lightly used, non-smoking >>> home $4,000 & shipped CONUS in original box. New this would run about $6200 >>> + shipping. >>> Contact: >>> Cary, K4TM >>> Lynchburg VA >>> H3cary at Gmail dot com >>> 434-660-8299 C >>> >>> >>> > > > ------------------------------ > > Message: 3 > Date: Fri, 26 Dec 2025 16:02:57 +0000 (UTC) > From: Mike Furrey <[email protected]> > To: "[email protected]" <[email protected]>, W3FPR > <[email protected]> > Subject: Re: [Elecraft] K2 Receiver dead > Message-ID: <[email protected]> > Content-Type: text/plain; charset=UTF-8 > > Hi all, > I have finally had a chance to help out with my friends K2. Using both the RF > signal generator and an AF generator, signals do get through on all bands but > is very weakly. Even with the signal generator on the IF frequency, the > signal is very weak, even at the input to the detector. We injected an AF > signal at the output of the detector and it is very robust ... great audio > and volume.? > What I have noticed ... The maximum strength on the S meter (still low) > occurs when the signal is zero beat, weather a signal is injected at the > antenna or an IF signal is injected at the input to the detector, the NE612. > I am currently suspecting a bad BFO output or an alignment somewhere. That is > currently where we stand. Any suggestions before we start again in the New > Year? Thanks. > 73, Mike WA5POK > On Friday, September 19, 2025 at 08:12:18 PM EDT, Mike Furrey via Elecraft > <[email protected]> wrote: > > Don, Thanks for the note. > I am currently at my TX home and when I return to TN in DEC, I am taking my > test gear (have plenty) to help my friend that has the non-receiving K2. I > have a decent Leader signal generator here and I use a frequency counter to > check the frequency.? I also just dug up enough parts to build a 10 mHz > generator.? > To get myself tuned up to working on the K2 I am going to go through mine > here. Been working on too many old boat anchors lately.? > 73, Mike WA5POK > ? ? On Friday, September 19, 2025 at 07:24:37 PM EDT, W3FPR > <[email protected]> wrote:? > > Mike, > > If you do not yet have a proper signal generator, try this - connect a > dummy load to the working K2, and set the power below 12 watts.? On the > dead receiver, attach a short wire (not coax) as an antenna about 1 foot > long), and place it close enough to the working K2's dummy load to > produce the proper voltage at the bad K2 input (do not move the wire > after that, and do not change the powering K2's power level).? Then > proceed with the receiver signal tracing as indicated in the manual.? > You can use the TUNE button to set the working K2 to transmit a signal) > > You should remove the KPA100 completely (Physically and electrically) > from the non-working K2 and use the lower panel BNC as the antenna input. > > Again, let me know the first stage where the output is decidedly below > normal - stop and tell me where that point is and we can troubleshoot > that stage to the component level.? I do not need/want any information > beyond that first failing point because it is not relevant until that > stage is repaired. > > 73, > Don W3FPR > >> On 9/8/2025 12:26 AM, Mike Furrey wrote: >> Hi Mike and Don, >> >> Thanks for the replies. We took out the 160 meter board and bypassed >> it with clip leads.It has s/n 36XX (trying to remember as Jim took it >> with him) We also pulled the KPA100 amp and used the BNC antenna jack >> to connect to a dummy load to check power output ... around 10 to 12 >> watts, then to an antenna to listen for signals. I will talk with Jim >> tomorrow? and we will start developing a plan on the bench. Most of my >> all of my test gear is at my TX home and we are currently in TN. I >> have a scope here and a test probe and might have enough stuff to >> build the crystal oscillator here ... once again plenty of stuff ... >> not in TN. Hi. >> >> Now that I just finished in the TNQP we will start a methodical look >> at the front end. >> >> We will keep y'all posted >> >> Thanks es 73, >> >> Mike WA5POK >> >> On Sunday, September 7, 2025 at 04:33:37 PM EDT, W3FPR >> <[email protected]> wrote: >> >> >> Mike, >> >> What is the serial number of that K2?? If below 100, it is a Field Test >> model and is slightly different that those above that SN. >> >> I would not recommending "shotgunning" the problem, there is a >> methodical way to go about it which will lead to the problem area >> without guesswork. >> >> The best way to troubleshoot a dead receive problem with the K2 is first >> to remove the KPA100 completely, and then test the base K2 from the >> lower panel BNC connector. >> See the Troubleshooting section of the K2 manual (Appendix E). Since you >> do not have a signal generator, you could build up the crystal >> oscillator shown on page 9 of the Appendix.? If you do not have a >> 'scope, you can use the RF probe also shown on page 9.? It does not have >> to be 'pretty' for this job, pushing the component leads though >> cardboard and soldering them together will work fine for the frequencies >> involved here. >> >> The troubleshooting steps begin on the right column of page 10 and >> continue thru the left column of page 12.? With the proper input level, >> you are looking to find the first stage that that has lower than >> expected output. >> Once you locate that stage, let me know and I can help you with >> component by component checks to solve the problem.? Dave Van Wallingan >> W8FGU can also assist since he is the current /major repair person for >> the K2 and other legacy gear that I used to repair. >> >> 73, >> Don W3FPR >> >> >>> On 9/7/2025 1:07 PM, Mike Furrey via Elecraft wrote: >>> At a hamfest a week ago there were two k2s for sale from an estate. >> I bought one and a friend (not on here yet) bought the other. His >> receiver is dead. The transmitter has full output (110 watts) on all >> bands. The receiver ... AF gain works, side tone works, filters work, >> and RF gain works. This can be heard in the change of the pitch/volume >> of the noise emitted. >>> ATTN and Preamp do not work/function. We see no codes. We made a >> cursory disassembly and unseated and reseated all the boards. It has >> the 160 meter option in, and we bypassed it.? Unfortunately I sold my >> old signal generator at the hamfest in anticipation of getting a more >> up-to-date unit. Hmmm mabe use my old Model 59 GDO as a generator. We >> are thinking relay ... haven't yet gone into it that far. One thing >> that puzzles me is the RF gain control (R4). Where is it in the >> circuit? I see it connected to J1. I see it coming off of P1 and that >> is it where it ends!!?? I see R5, R6, R7, etc but I can't find where >> R4 connects? I am thinking a relay somewhere in there? loose jumper or >> plug I have overlooked? Maybe someone can throw me a bone as to a hint >> as to where to look for the missing RF to the receiver. >>> Many Thanks, Mike WA5POK >>> ______________________________________________________________ >>> > > ? > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [email protected] > > ------------------------------ > > _______________________________________________ > Elecraft mailing list > Post to: [email protected] > http://mailman.qth.net/mailman/listinfo/elecraft > You must be a subscriber to post. > Elecraft web page: http://www.elecraft.com > > End of Elecraft Digest, Vol 260, Issue 24 > ***************************************** ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
