RE:K3 as a SW receiver
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For AM SW listening be sure to get the "FM" filter (13 kHz). It gives
you the width you need for the audio bandwidth you expect. The normal SSB filter (I have the 2.8) is too restricting for AM. However, I find that switching mode from AM to SSB reduces severe fading and distortion, much like AM synchronous detection does (fills in the missing carrier). It's a good technique, at least until synch detection is implemented in the firmware. Windy KM5Q K3 #764 _______________________________________________ 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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KM5Q wrote:
> For AM SW listening be sure to get the "FM" filter (13 kHz). It gives > you the width you need for the audio bandwidth you expect. The normal > SSB filter (I have the 2.8) is too restricting for AM. > > However, I find that switching mode from AM to SSB reduces severe > fading and distortion, much like AM synchronous detection does (fills > in the missing carrier). It's a good technique, at least until synch > detection is implemented in the firmware. Windy, Also note that our 6-kHz 8-pole filter is targeted specifically at AM operation, and will provide better adjacent-channel QRM rejection than the FM filter, if needed. A 6-kHz filter is also required for AM transmit (enforced in firmware). This ensures excellent 2nd-I.F. image rejection. 73, Wayne N6KR --- http://www.elecraft.com _______________________________________________ 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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G'day,
Aren't there still some issues re VFO management when wide range tuning. The band switching can go pear shaped. Regards, Mike VP8NO ----- Original Message ----- From: "wayne burdick" <[hidden email]> To: "KM5Q" <[hidden email]> Cc: <[hidden email]> Sent: Wednesday, December 31, 2008 6:16 AM Subject: [Elecraft] Re: K3 as a SW receiver | KM5Q wrote: | | > For AM SW listening be sure to get the "FM" filter (13 kHz). It gives | > you the width you need for the audio bandwidth you expect. The normal | > SSB filter (I have the 2.8) is too restricting for AM. | > | > However, I find that switching mode from AM to SSB reduces severe | > fading and distortion, much like AM synchronous detection does (fills | > in the missing carrier). It's a good technique, at least until synch | > detection is implemented in the firmware. | | Windy, | | Also note that our 6-kHz 8-pole filter is targeted specifically at AM | operation, and will provide better adjacent-channel QRM rejection than | the FM filter, if needed. A 6-kHz filter is also required for AM | transmit (enforced in firmware). This ensures excellent 2nd-I.F. image | rejection. | | 73, | Wayne | N6KR _______________________________________________ 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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In reply to this post by KM5Q
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I'd respectfully suggest that anyone who has made this as a serious suggestion for SWBC listening, has never done any serious SWBC listening ;-)
By all means, if you want to listen to AM SWBC (or AM on the ham bands for that matter) you need at a minimum the 6Khz filter, and I'd recommend the FM (13Khz) filter as well. And then I'd recommend continuing to bug Elecraft about the sync AM detector, and good flat LF response down to at least 70-80 Hz. Or better yet, buy an R-390A or SP-600 or something similar -- but there's no real reason the K3 can't meet that need as well have adjustably tighter specs for those who never venture outside the ham bands or think the AM mode should be deleted from the firmware :-) Grant/NQ5T On Dec 31, 2008, at 10:49 AM, Barbara Maloney wrote:
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In reply to this post by KM5Q
I agree with Mike that for occasional listening to AM stations outside
the ham bands, the stock SSB filter in SSB mode is fine. Zero beat the station and it sounds OK. Switch to AM mode and it's too narrow. For tuning around casually, having to listen to carriers as you tune is annoying. The 13 kHz FM filter adds a lot of quality to the fidelity, and lets you tune and listen in AM mode with pleasant results. And yes, other Mike, bandswitching and VFO management are still problematic outside the ham bands. Windy KM5Q _______________________________________________ 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 |
Re: K3 as a SW receiver
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Just have to add my two cents here. For me personally, this has
nothing to do with relaxing, high-fidelity AM listening. It has everything to do with weak-signal SWBC DXing. I've been a serious SWBC DXer off and on for 50 years, and I've used all kinds of receivers, including a fully rehabbed and up-to-spec R-390A, which I would not part with for anything. HOWEVER, for digging weak AM signals out of adjacent channel QRM, I've yet to find anything better than a good steep-skirted SSB filter in the IF. And, since (as stated below) it IS very annoying to tune through all those whooping carriers... Don't do it! It's easy to avoid most of them, especially when listening to SWBC stations, which are typically on 5-kHz channels. Set up the RIT knob to act as the VFO CRS tuning when RIT is not engaged. Then set up the VFO CRS config parameter to 5.0 kHz steps and use the RIT knob to tune to the appropriate channel. Use the main tuning to zero it in if necessary. Toggle MODE:ALT to switch between the USB and LSB sides of the carrier and listen to the side with the least QRM. In the absence of QRM on either side, you can also switch quickly back and forth between sidebands as QSB changes which one is coming through the best. In the absence of a synchronous detector, this works pretty darn good, IMO. Bill W5WVO KM5Q wrote: > I agree with Mike that for occasional listening to AM stations outside > the ham bands, the stock SSB filter in SSB mode is fine. Zero beat the > station and it sounds OK. Switch to AM mode and it's too narrow. For > tuning around casually, having to listen to carriers as you tune is > annoying. > > The 13 kHz FM filter adds a lot of quality to the fidelity, and lets > you tune and listen in AM mode with pleasant results. > > And yes, other Mike, bandswitching and VFO management are still > problematic outside the ham bands. > > Windy KM5Q > > > _______________________________________________ > 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 _______________________________________________ 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 |
RE: Re: K3 as a SW receiver
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In reply to this post by wayne burdick
> Also note that our 6-kHz 8-pole filter is targeted specifically > at AM operation, and will provide better adjacent-channel QRM > rejection than the FM filter, if needed. "Targeted specifically at AM operation" is correct only in the context of amateur "communications." The 6 KHz filter bandwidth limits the audio bandwidth to 3 KHz before the skirt selectivity starts to create significant rolloff. If one is looking for SW or MW broadcast reception the 13 KHz FM filter would provide significantly better fidelity - particularly if the 4 KHz DSP audio frequency limit was increased to 5.5 or 6.0 KHz (at least for AM). > A 6-kHz filter is also required for AM transmit (enforced in > firmware). This ensures excellent 2nd-I.F. image rejection. This could certainly be relaxed to allow use of the 13 KHz filter for AM transmit. Even if the 13 KHz filter had only a 2:1 shape factor, with the carrier centered in the filter response at the image frequency (30 KHz away) should be very close to the filter's ultimate rejection ... shifting the filter 2 or 2.5 KHz away from the image in transmit would provide even more insurance against unwanted image response. 73, ... Joe, W4TV > -----Original Message----- > From: [hidden email] > [mailto:[hidden email]] On Behalf Of wayne burdick > Sent: Wednesday, December 31, 2008 4:17 AM > To: KM5Q > Cc: [hidden email] > Subject: [Elecraft] Re: K3 as a SW receiver > > > KM5Q wrote: > > > For AM SW listening be sure to get the "FM" filter (13 > kHz). It gives > > you the width you need for the audio bandwidth you expect. > The normal > > SSB filter (I have the 2.8) is too restricting for AM. > > > > However, I find that switching mode from AM to SSB reduces severe > > fading and distortion, much like AM synchronous detection > does (fills > > in the missing carrier). It's a good technique, at least > until synch > > detection is implemented in the firmware. > > Windy, > > Also note that our 6-kHz 8-pole filter is targeted specifically at AM > operation, and will provide better adjacent-channel QRM > rejection than > the FM filter, if needed. A 6-kHz filter is also required for AM > transmit (enforced in firmware). This ensures excellent > 2nd-I.F. image > rejection. > > 73, > Wayne > N6KR > > --- > > http://www.elecraft.com > > _______________________________________________ > 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 _______________________________________________ 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,
I use the K3 for AM SWL reception all the time and find it quite capable. I use the 13kHz FM filter. I don't even have the 6kHz filter. I have no intention of ever transmitting on AM or for that matter FM. For good strong AM stations I set the passband from 100Hz to 4.2kHz and enjoy quite good audio. Yes, I wouldn't mind even a little wider hi cut but once you reach 5kHz whistles form adjacent stations become a problem. Right now I am monitoring WWV with Spectrum Laboratory on the line output and Heil headphones on the front panel and clearly see and hear the full spectrum from 100-4200Hz. WWV has a tone at 100Hz which is clearly audible and visible (my DSP hardware is unmodified). I don't know how much more you can ask. Well OK, please get rid of the bugs associated with the passband tuning and the associated graphic. E.g. the low cut of 200Hz is skipped on the way up but available on the way down (and others that are well documented).
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Do I get a prize for the first 2009 message (according to the time stamping in the MARC database)?
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Hello again again,
On the issue of using the SSB mode for AM reception, having a look at this spectrum snip from LP-PAN: http://ab2tc.getmyip.com:82/pictures/amreception.jpg Look at that monstrously wide local station at 1490kHz. Using USB mode the distant station at 1500kHz is perfectly copyable, in fact the disco music from 1490 is barely noticeable. No other mode will bring the 1500kHz station through. The K3 has such great suppression of the opposite sideband that there is absolutely no flutter (which is usually a problem with analog radios) when zero beating an AM station. You bet, SSB mode reception of AM stations is a very good option in difficult situations with this radio.
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PS.
You can log in to remotehams.com and check out the situation yourself on my lesser radio IC-718 but which still can copy the 1500kHz station but with the flutter aforementioned. Happy new year, BTW.
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In reply to this post by ab2tc
How does it sound in PowerSDR SAM mode, with filter adjusted to just inside the adjacent stations? This is how I usually listen to AM broadcasts.
Larry N8LP
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PowerSDR in SAM mode sounds great. In all modes the audio from PowerSDR is consistently better than from the K3 using the same headphones. Of course with SAM there is no direct comparison since the K3 still lacks that option. I didn't try, but I bet SAM would loose lock in the situation above. I might try that tonight.
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