Granted this thread is moribund at this point, but... With Bill's nice summary of existing products, it got me to thinking about this again after comparing the MFJ and Timewave products a few years back. I believe the DXE product is new since my last survey of the field.
I'm primarily a 6-meter weak-signal operator, and neither the DXE not the MFJ product is characterized for operation above 30 MHz. The ANC is, last time I checked. (Their website is down right now so can't re-check.) I've studied enough about the designs of the MFJ and ANC to understand why the ANC is at the bottom of Bill's list. I think. It has to do with phasing range, mostly, in which both the MFJ and ANC products are deficient, but the ANC more so. There may be other faults in the ANC design as well; I believe the MFJ's ability, not present in the ANC, to phase to an "add" (0 degrees) condition and then invert has been mentioned. If the phasing need in your particular situation happens to be within the range that the ANC can match, you're probably going to think it's great. But that's a crap-shoot. My question from several years ago is still the same now, with the addition of the DXE product to the mix: Why are the MFJ (and now DXE) products characterized only through 30 MHz? Would they really not work acceptably at 50 MHz, or are we talking about a small amount of degradation in performance that might be seen as an acceptable trade-off? Or do they just flat-out not work on 6 meters? What would be necessary in the way of design mods to get the DXE product, for example, to perform at 50 MHz? Has anybody ever looked into this? Bill W5WVO -----Original Message----- From: Bill W4ZV Sent: Tuesday, November 30, 2010 15:08 To: elecraft@mailman.qth.net Subject: Re: [Elecraft] Reï¼ Diversity Receive as Noise C anceling? Edward R. Cole wrote: > > I'm not sure that adapting the sw for noise > cancellation will take that much extra > processing. Reversing phase is a simple digital > inversion. > It's also very simple to do at RF with one of the external phase boxes. I've used all 3 of these and rate them in the following order: 1. DXE NCC-1 (the best but expensive) 2. MFJ-1025 (very good with W8JI's mods below) 3. Timewave ANC-4 References: http://www.dxengineering.com/Parts.asp?ID=1227&PLID=215&SecID=114&DeptID=12&PartNo=DXE-NCC-1 http://www.mfjenterprises.com/Product.php?productid=MFJ-1025 http://www.w8ji.com/mfj-1025_1026.htm http://www.timewave.com/support/ANC-4/anc4.html I personally wouldn't give up diversity for noise canceling, but I don't live on a city lot. I'd use an external phase box with noise sense antenna aimed at the noise source combined with an RX antenna via a phasing box into RX ANT and a second RX antenna into AUX RF for diversity. Using DSP to do what a $180 box does reasonably well seems like overkill. This reminds me of the Flex Radio guru who proposed a 4 RX/TX solution to what an external 4SQ phase box does for $350...plus you need only one feedline to the controller instead of 4 to the shack, one 1.5 kW amp instead of 4 each $375 amps, and much less complexity. "A technical solution looking for an application" comes to mind. 73, Bill -- View this message in context: http://elecraft.365791.n2.nabble.com/Diversity-Receive-as-Noise-Canceling-tp5782138p5788410.html Sent from the [K3] mailing list archive at Nabble.com. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
