K2 Dual Recieve Plans - Comments Wanted

[John Huffman-2]

I would appreciate comments on my plans to use my K2 for dual receive.

I'd like to use my K2 with my Ten-Tec Pegasus in a dual receive setup.  I would
listen with either the K2, the Pegasus, or both.  I would transmit with the
Pegasus.

I can use N4PY software to have the Pegasus track to the frequency set by the
K2.

For antenna switching I would modify the Pegasus to have an AUX receiver output
at the "spare" jack on the back of the Pegasus.  Instructions are in the N4PY
documentation.  The instructions state that "This jack is fully protected from
high transmit power when transmitting."  For K2 input I would build the K160M
module to add a second receive port to the K2 and would use that port as input
for the AUX receiver output from the Pegasus.

My concerns are how to protect the K2 from getting the front end blown up by the
Pegasus and how to mute the K2.

I plan on hooking a dummy load to the regular K2 antenna input.  I would do the
"Simple K2 RX mod handles extremely strong on-frequency signals" from the web
site which puts diodes across the IF amp.

For muting the K2 I can use the Pegasus EXT T/R jack which is an open collector
transistor switch rated at up to 24v and 200ma.  The delay is adjustable.  But,
I'm stuck as to how to take that switch and mute the K2.

I could connect the switch to a relay across the headphones.

I could use that switch to trigger the key input of the K2 to switch the K2's
internal TR switch.

Neither seems like the right solution.

Advice greatly appreciated.

73 de NA8M
John

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[n6wg]

John
I will be using a pair of K2's in a QRP SO2R configuration, very similar to
what
you propose.
One point on muting the Rx only K2.  I've seen a lot of posts trying to
figure
oput a way to do this, but don't recall seeing any clean approaches.  Your
idea of using the key jack is very clean.  Just remember to put the K2 in
TEST mode so you don't key the TX, and turn the sidetone down to zero so you
don't have to listen to it.

I use TR LOG here, and it has a key command to swap the frequency between
the
rigs in use, so that's how I will operate.  One rig with all the antennas,
and
one with just a receive antenna.  I will be building a bunch of bandpass
filters
to keep the TX out of the search RX.  You can either buy your filters, or
try to build them.  I'll be using the filters in the July/Aug 1999 QEX
article
by Ed Wetherhold, W3NQN, titled "Receiver Band-Pass Filters Having Maximum
Attenuation in Adjacent Bands".  These filters look to be very straight
forward,
so I'm confident I can build them.

Good luck and 73
Bob N6WG
The Little Station with Attitude

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]]On Behalf Of John Huffman
Sent: Wednesday, March 15, 2006 3:19 AM
To: Elecraft
Subject: [Elecraft] K2 Dual Recieve Plans - Comments Wanted


I would appreciate comments on my plans to use my K2 for dual receive.

I'd like to use my K2 with my Ten-Tec Pegasus in a dual receive setup.  I
would
listen with either the K2, the Pegasus, or both.  I would transmit with the
Pegasus.

I can use N4PY software to have the Pegasus track to the frequency set by
the
K2.

For antenna switching I would modify the Pegasus to have an AUX receiver
output
at the "spare" jack on the back of the Pegasus.  Instructions are in the
N4PY
documentation.  The instructions state that "This jack is fully protected
from
high transmit power when transmitting."  For K2 input I would build the
K160M
module to add a second receive port to the K2 and would use that port as
input
for the AUX receiver output from the Pegasus.

My concerns are how to protect the K2 from getting the front end blown up by
the
Pegasus and how to mute the K2.

I plan on hooking a dummy load to the regular K2 antenna input.  I would do
the
"Simple K2 RX mod handles extremely strong on-frequency signals" from the
web
site which puts diodes across the IF amp.

For muting the K2 I can use the Pegasus EXT T/R jack which is an open
collector
transistor switch rated at up to 24v and 200ma.  The delay is adjustable.
But,
I'm stuck as to how to take that switch and mute the K2.

I could connect the switch to a relay across the headphones.

I could use that switch to trigger the key input of the K2 to switch the
K2's
internal TR switch.

Neither seems like the right solution.

Advice greatly appreciated.

73 de NA8M
John

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[Don Wilhelm-3]

Folks,

I may be missing something here, but with my understanding of SO2R
operation, one would not want to mute the receive K2 so that you could scan
for other stations while the transmit K2 is CQing or doing some other
semi-automated transmit task.  In this situation, the solution would be to
work on the antenna isolation so the transmit transceiver does not unduly
overload the receive transceiver.

I would think that assuring that the K2 is placed in TEST mode would be a
risky way to handle the situation - although it will work technically, the
problems of making certain the receive K2 is in TEST mode during 'the heat
of the battle' sounds like a disaster waiting to happen.

73,
Don W3FPR

> -----Original Message-----
>
> John
> I will be using a pair of K2's in a QRP SO2R configuration, very
> similar to
> what
> you propose.
> One point on muting the Rx only K2.  I've seen a lot of posts trying to
> figure
> oput a way to do this, but don't recall seeing any clean approaches.  Your
> idea of using the key jack is very clean.  Just remember to put the K2 in
> TEST mode so you don't key the TX, and turn the sidetone down to
> zero so you
> don't have to listen to it.
>
>

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