Date: Wed, 24 Jan 2001 13:14:28 -0800 From: Wayne Burdick Subject: Re: [Elecraft] K1 filter question Tom Hammond NØSS wrote: > > Steve: > > >Second concerns the filters. I may be spoiled ... Steve, I think I understand your issue; you may the first one to mention it. Since the K2's CW filter covers a wide range of passbands (~200-1500 Hz or more), it makes the narrow settings *really* stand out. In contrast, the K1's filters range from only about 200-800 Hz. So when switching filters on the K1, there won't be high drama--only a narrower passband--and it's not as easy to hear the difference. Still, the narrow filters work very well in reducing QRM. I suggest the following experiment: tune in a low-pitch (500-600 Hz) signal using FL3, on a very busy band where you can hear one or more higher-pitch stations (the louder the better!). Then drop to FL2, then FL1, and you should hear the higher-pitch stuff just dissappear. The skirts are more than adequate; at the low I.F. used in the K1, they're much sharper than they would be if a more typical I.F. of 8-9 MHz was used. An interesting bit of techincal trivia: the K1's crystal filter is driven by a very low-impedance source follower, which favors narrower passband settings. As a result, there is almost no audible decrease in signal amplitude at the filter's center frequency as you reduce the width. 73, Wayne N6KR - --- Submissions: elecraft at qth.net Please note: The list server automatically rejects HTML encoded emails. List Archive page: http://www.qth.net/archive/elecraft/elecraft.html Elecraft Web Page: http://www.elecraft.com ------------------------------ Date: Wed, 24 Jan 2001 12:16:14 -0800 From: steven.e.huss at exgate.tek.com Subject: [Elecraft] K1 filter question Been real pleased with my K1. It will make a nice alternative to my K2 when I travel light. Thanks Elecraft! Also, it was a blast to build but it sure went fast compared to the K2! Someday I might change to the 80k tuning range... hard to beat the synthesized tuning of the K2 . Two observations: This one is very minor. The ATTN LED is a little low in intensity though it measures 1 and 3 volts on the two legs respective to gnd when activated... just like the XIT LED. The resistor values identify correctly but have not been measured. When the battery display is activated the blinking ATTN LED is only detected when all room lights are turned off and even then is very faint. Like I said... very minor and no big deal. Second concerns the filters. I may be spoiled by the K2 but the K1 filters don't seem to be as sharp. I stayed with the default filter values and when going from F1-F3 there just is not that much practical difference. Using Spectrogram the K2 filters appear more square wave like, where as the K1's are more sloping. Could I have messed something up somehow? Thanks for any suggestions and 73, Steve Kc7zvm ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Date: Mon, 16 Apr 2001 07:37:21 -0500 From: Mike Subject: Re: [Elecraft] K1 filter alignment question Andy Anderson wrote: > However, the 7050 sounded muted, course, and "scratchy" as if it was > way over-driven You'll get the best (sharpest) alignment, and be able to find the proper peak response, if you use the MINIMUM level of test signal. I tuned my K1 with a 5-inch wire in the BNC for an antenna, and a short wire stuck to an MFJ-259 antenna analyzer across the room as the signal source. Even that was too much signal once the bandpass filter coils were close to proper alignment. I could definitely be wrong, but it sounds to me like you had too much test signal. When you get to the transmitter alignment, you'll be re-aligning ALL the bandpass coils again for peak output. I wouldn't worry too much about the precise alignment yet, unless your test signal so swamped the input that it caused you to mis-align on a spurious peak. > F1, F2, and F3 seem to work FB as well. I don't understand what the above means with respect to a K1. > Do I just need to go back and re-do the 40m alignment? > What should I look for? Try it using the absolute MINIMUM amount of test signal. > Also, how do I capture these so they can be added to the Elecraft > "Builder's Resource" page? What needs to be added??? 73, Mike / KK5F +++++++++++++++++++++++++++++++++++++++++++++++ Date: Thu, 3 May 2001 10:58:00 -0700 From: steven.e.huss at exgate.tek.com Subject: [Elecraft] K1 filters Hello All, Some time ago I voiced a concern I had about my K1's three bandwidth filters. While they were narrow enough, there just was not that much perceived difference between the three using the default values. Bottom line, I did not think filter #1 was as wide as it should be. As it turns out I stated my concern quite poorly but Wayne still came back with some very good comments. You can see all this in the new summarized area of the reflector under "K1 filters". I then left it at that. After all... no one should complain about not having too wide of a filter! After my buddy built his K1 I could now perform a comparison. There was a big difference in the default #1 filters of his and mine. This lead to an email to Gary and he suggested checking the bias of D6-D8. Turns out I did not solder pin #1 of RP1! D6 never got biased. Once I made the correction all worked as expected. Hey... there are times when it is nice to have a wider bandwidth! Fact is, I would never have sent my original email if I had not made a mistake in soldering. While I'm sure Wayne's comments are true, I am very happy with the K1 filters! It might be a good thing if this follow up could be added to "Elecraft - Reflections From Their Reflector" so folks can see the full picture. Thanks and 73, Steve kc7zvm ++++++++++++++++++++++++++++++++++++++++++ Date: Thu, 03 May 2001 11:50:05 -0700 From: Wayne Burdick Subject: Re: [Elecraft] K1 filters Thanks for your comments, Steve. I'm glad you got it fixed! Wayne steven.e.huss at exgate.tek.com wrote: > After my buddy built his K1 I could now perform a comparison. There was a > big difference in the default #1 filters of his and mine. This lead to an > email to Gary and he suggested checking the bias of D6-D8. Turns out I did > not solder pin #1 of RP1! D6 never got biased. Once I made the correction > all worked as expected. Hey... there are times when it is nice to have a > wider bandwidth! +++++++++++++++++++++++++++++++++++++++++ Date: Sun, 25 Nov 2001 14:42:17 -0800 From: Wayne Burdick Subject: Re: [Elecraft] K1 and ABX Hi Mike, "ABX" (adjustable bandwidth crystal filter) is a term I dreamed up when I added varactors to the Sierra design. The K1's three bandwidth selections perform the same function, but with three discrete set points. 73, Wayne N6KR >mike wrote: > > I just ordered the K1-4 this week. Does this rig have ABX or is the > question totally not applicable to this rig? ++++++++++++++++++ From: "Jerry Ford" To: Subject: Fw: [Elecraft] K1 crystals Date: Fri, 1 Mar 2002 02:10:41 -0600 David: I remember when the discussion came out about this mod. I was building my first K-1 at the time. I ask at that time if this mod could be applicable to the K-1 as like you, I wanted to build mine right rather than changing it later. I remember the answers I got were along the line that there was a diffenence in the 2 rigs wherein the K-2 would realize an advantage but the K-1 would not. I'm sure you can take a look in the archives and find those threads. I would also expect that some of the folks here will be able to quote those threads and give you the reasons why the K-1 won't be affected by the mod. Just to long ago and its too late at night for me to recall. Anyway, I can tell you that the answer I got at the time was a resounding " No, it won't help " I'll be watching other responses to your question to see if anything has changed in recent months. 73 and g l de Jerry N0JRN ----- Original Message ----- From: "David Pratt" To: "Elecraft Reflector" Sent: Friday, March 01, 2002 1:18 AM Subject: [Elecraft] K1 crystals > Having built a K2 and subsequently changed the positions of the > grounding wires to improve the rejection characteristics of the filter, > I should like to ask whether there is any similar advantage in grounding > the crystals in the K1 at the bottom, rather than at the top, of the > crystal cans? > > I appreciate the care necessary in soldering the grounding wires to the > crystals, but if there would be improvement in soldering the wires at > the bottom, I would prefer do it now while building the K1 rather than > modify it later. > > 73 > > David G4DMP ++++++++++++++++++