[Elecraft] K3 Receiver Protection

[Jeff Stai]

The simplest "get you there now" solution is to simply disable
complimentary bands in each K3. Set up the left radio for 80-20-10 and the
right radio for 160-40-15, for one example.

You didn't buy Steppirs to exclude bands on each radio, but this will give
you protection now while you pursue one of the other suggestions.
(Obviously, avoid using direct frequency entry to change bands...)

Also, highly recommend purchasing this book, for the next steps of keeping
one radio from bothering the other:

http://www.inrad.net/product.php?productid=248

Have fun! 73 jeff wk6i



On Sun, Jun 1, 2014 at 9:44 AM, Cady, Fred <fcady at ece.montana.edu> wrote:

> Check out a 74LS85 4 bit comparator.  A single chip with the A=B output
> going to each of the K3's ACC pin 7, TX INH inputs.
> 73,
> Fred KE7X
>
>
> > -----Original Message-----
> > From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of
> > Joe Subich, W4TV
> > Sent: Sunday, June 01, 2014 9:28 AM
> > To: elecraft at mailman.qth.net
> > Subject: Re: [Elecraft] K3 Receiver Protection
> >
> >
> > > If the serial ports of the K3s are available,
> >
> > They tend not to be when doing SO2R - the logger has them tied up.
> > Of course if the Arduino is capable of handling four 38,400 bps ports
> > at the same time one can pass the logger data through the device.
> >
> > 73,
> >
> >     ... Joe, W4TV
> >
> >
> > On 2014-06-01 11:19 AM, Doug Person via Elecraft wrote:
> > > This would be a good place to use an Arduino.  If the serial ports of
> > > the K3s are available, it would only take a small bit of code to
> > > achieve this.
> > >
> > > Doug -- K0DXV
> > >
> > > On 05/31/2014 10:46 PM, Don Wilhelm wrote:
> > >> Jeff,
> > >>
> > >> That is a logic question seeking an answer.  I don't know of a
> > simple
> > >> solution, but it is a matter of selecting a match of the outputs of
> > 2
> > >> band data decoders.  If any two are the same, assert TX INH to both
> > K3s.
> > >>
> > >> That function could be implemented with a number of NAND gates or
> > XOR
> > >> gates at the outputs of the 2 band decoders.  The exact
> > >> implementation of the logic gates is "left to the student", there
> > are
> > >> several possibilities, but it would take a number of external logic
> > >> gates to implement.
> > >>
> > >> If you are really into logical devices, you could program a chip to
> > >> do that directly from the band data outputs - if all 4 of the
> > outputs
> > >> from both K3s are a match, assert TX INH to both transceivers.
> > >>
> > >> I do not know of an existing device that will provide that function,
> > >> so the implementation would have to be created 'from scratch'.  Yes,
> > >> it is possible, it is just a matter of "a few logic gates".
> > >>
> > >> 73,
> > >> Don W3FPR
> > >>
> > >> On 6/1/2014 12:04 AM, Jeff via Elecraft wrote:
> > >>> My station consists of two K-3's, each with a dedicated legal limit
> > >>> amplifier and SteppIr antenna. To minimize interference between
> > >>> bands I am using Array Solutions Bandpass filters. However, if both
> > >>> rigs accidentally wind up on the same band I run the risk of
> > >>> overloading the front end of the opposite rig and damaging the
> > >>> receiver (which I've done once...). Does anyone have a way of
> > taking
> > >>> the band data information and disabling transmit capability on both
> > >>> rigs if they are on the same band? How are others using SO2R
> > >>> avoiding same band transmission and subsequent receiver damage?
> > >>> Anyone have any experience with the Array Solutions AS-RXFEP front
> > end protector?
> > >>>
> > >>
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-- 
Jeff Stai ~ wk6i.jeff at gmail.com
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