Reposting this since the Elecraft list on qth.net was down earlier:
Bill W4ZV wrote: > > I believe many are now receiving their KRX3s and are about to discover the > amazing benefits of True Diversity with the K3. As some of you know, I > love to chase DX on 160 and will only say Diversity is something I will > never be without. I typically use a directional 3-el vertical array on > transmit and a Beverage in the same direction on receive. In Diversity > mode, I use my TX antenna on Main and the Beverage on Sub. Sometimes it's > absolutely amazing to hear signals switching back and forth between ears > in <1 second! I'm sure these signals would exhibit extreme QSB if > listening on one antenna by itself. > > Although the K3 has an effective switching system for most use, there's > one situation which I've run across which needs an external solution. > This is the (somewhat unusual) case when a signal will be present on only > one of the antennas being used in Diversity. I found I wanted a quick way > to switch out of Diversity, so that either the TX or RX antenna alone > would be applied to both ears. Otherwise I'm feeding extraneous noise > with no signal to one of my ears. > > A simple solution to this is to use an external splitter for the Beverage > input. This should be a Magic-T splitter (not just a T-connector) which > preserves impedance and isolation between the two receiver channels. You > can either build one yourself (using two ferrite cores and a resistor) or > buy a commercial unit (Mini-Circuits ZSC-2-2 or DXE RSC-2 are both ~$50). > The Mini-Circuits unit is available in either 50-50 ohm or 75-75 ohm > versions and the DXE is 75-75 only. If you make it yourself, you can make > one which will match a 75 ohm antenna to the 50 ohm RX inputs of the K3. > See W8JI's website for details to roll your own: > > http://www.w8ji.com/combiner_and_splitters.htm > > So how does this work? I feed my Beverage to the splitter and then > connect its two outputs to RX ANT and AUX RF. When I want Diversity, I > use my TX antenna (ANT1) on Main and the Beverage on AUX RF (the KRX3 > allows you to choose either the same antenna as Main or AUX RF). Here are > the two cases to switch from Diversity to either the TX array or RX > antenna using a splitter. > > 1. When I want my Beverage on both ears, I simply "tap" RX ANT. To go > back to Diversity Mode, I "tap" RX ANT again. > > 2. When I want my TX array on both ears, I "hold" RX ANT which switches > the KRX3 to the same antenna as Main. When I want to return to Diversity, > I "hold" RX ANT again. > > One tap or hold and you instantly can go out of (or back into) Diversity > with either your TX or RX antenna in those rare cases when a weak signal > may be on only one antenna. > > There's of course a ~3 dB loss when you use a splitter, but this isn't > significant on the low bands since the external noise floor is so far > above the noise floor of the K3 (...even if ATT is on). > > True Diversity in the K3 is a remarkable achievement compared to other > rigs costing much more (neither the IC-7800 or Orion has True Diversity). > In my configuration, I have it in a rig which cost me ~$2.8k including 6 > filters (2 of which are unnecessary for non-contesters, i.e. a 1.8k and > 200). > > If you want to hear some recordings using Diversity, listen to EI6IZ's CW > and SSB pileups here: > > http://ei6iz.com/ (Audio links at the bottom of his KRX3 article, and you > really need stereo headphones for the full effect. BTW, I never use > anything but headphones for DXing or contesting.) > > 73, Bill W4ZV > > > -- View this message in context: http://n2.nabble.com/-K3--KRX3-Antenna-Flexibility-tp1499595p1500426.html Sent from the Elecraft mailing list archive at Nabble.com. _______________________________________________ Elecraft mailing list Post to: [email protected] 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
