[Elecraft] K3 SO2R Question

[WILLIS COOKE]

Jim, for single band operation the sub-receiver works very well and does not need additional filters.  If you find a mult on the sub, just stop your CQ, tap A/B, make your call, then tap A/B and go back to CQ.  You don't need another K3 on the same band for that.
 Willis 'Cookie' Cooke 
K5EWJ 




________________________________
From: Jim Harris <w0em at q.com>
To: w5ov at w5ov.com; Elecraft Email <elecraft at mailman.qth.net>
Sent: Tue, March 9, 2010 11:08:42 AM
Subject: Re: [Elecraft] K3 SO2R Question


Bob,

I live on a postage size lot so big antennas and lots of separation is not possible.  I usually run an ALS-500M amp.  My initial thought is to run both K3's on the same bands.  However, digging out mult's on different bands might be the way to go.  The same band idea came from my days with duel watch radio's.  It's all a growing and learning experience.  

I've looked at the ICE filters plus those from other companys.  I'm guessing at this point the more isolation (expensive) filters would be better.  I've discovered in the last day or so that when signal levels are over about S9+30/40 the K3 receiver goes strangely quiet and no bars on the S-meter are light.  It takes from a few seconds to a minute or so to recover.

Thank you for your suggestions.

CU in the Colorado QSO Party Sept 4th, 2010.

73,  Jim, W0EM




> From: W5OV at W5OV.COM
> To: w0em at q.com; elecraft at mailman.qth.net
> Subject: RE: [Elecraft] K3 SO2R Question
> Date: Mon, 8 Mar 2010 17:20:49 -0600
> 
> Jim,
> 
> Are you asking if you can run high power SO2R and do so safely without
> bandpass filters? You didn't mention what power level, and this makes a huge
> difference.
> 
> You can use ICE bandpass filters (-30 to -35db) which are relatively cheap
> (~$40 each). Their performance is not as good as W3NQN design filters (-75db
> to -80db) which are the ones that cost big bucks(~$99 each). If you allocate
> one radio to doing say 160, 40 and 15 and the other to doing 80, 20 and 10m,
> you could get by with just one set of 6 bandpass filters.
> 
> While bandpass filters have a by-product of protecting your radio's front
> end, that's not all they do. The filter on the transmitter limits what gets
> out and the filter on the receiver limits what gets in - so having a filter
> on each radio increases the benefit. This is more of a practical operational
> thing than being protective. 
> 
> Also, when you say "separation of frequencies within the band" do you intend
> to run both radios on the same band? Needless to say, bandpass filters will
> not be of any use if you do this. The key here is physical separation of
> your antennas so that the coupling between the two is minimized.
> 
> Bob W5OV
> 
> P.S. ICE has a new owner and is delivering product again much more quickly.
> 
> 
> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net
> [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Jim Harris
> Sent: Monday, March 08, 2010 4:03 PM
> To: Elecraft Email
> Subject: [Elecraft] K3 SO2R Question
> 
> 
> Hi Folks,
> 
> I'm currently selling an off-shore rig with the hopes of acquiring a second
> K3 for SO2R, primarily for RTTY contesting.  I believe I've seen somewhere
> in the not to distant past that is was said the K3 receive front end can
> withstand 1-2 watts without damage.  I've spent the last hour reviewing the
> email archive and can find no reference to that.  Can anyone confirm or deny
> my remembrance?  (Or, is it all just wishful thinking?)  Is there anyone on
> the reflector that is operating a K3 SO2R station without the thousand or so
> dollars of band pass filters needed to protect the radio's front end?
> 
> Second part of the question is.....if possible to not damage the front end,
> what is the possibility of desensing or causing blocking or noise that would
> interfere with reception on one receiver when transmitting on the other
> radio.  I'm sure that is highly dependent on band(s) and separation of
> frequencies within the band.  I'll fully aware of the K3's ability to
> completely block signals a few kilohertz away but when RTTY contesting I do
> seem to notice there may be some desensing or AGC action from these signals
> even though they are not heard or processed by MMTTY.
> 
> Comments very much appreciated.
> 
> CU in the Colorado QSO Party Sept 4th, 2010.
> 
> 73,  Jim, W0EM
> 
> 
>                          
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