Re: [Elecraft] K3 ANT 1-2 isolation

2012-04-29 Thread Mike Harris
Interesting.  I looked at it from the other direction.  With the K3 ANT1 
connected to a dummy load and ANT2 connected also to a dummy load via my 
WM-2 QRP wattmeter.

With 100W out at ANT1, out of ANT2 I measured 30mW at 50MHz down to 1mW 
at 7.1MHz.  A range of -30dB to -50dB.  50MHz is not in the WM-2 spec, 
however, 25mW was measured at 28.2MHz which gives -36dB.

There are obviously potential measurement errors there so no one needs 
to take it as absolute. Perhaps someone with access to precision 
equipment could also do the test.

Regards,

Mike VP8NO



On 28/04/2012 12:27, Mark - G4AXX wrote:
 The isolation between ANT 1 and ANT 2 varies from -76dB at 1.8MHz to -46dB at
 50MHz.
 This is measured with a signal generator, using the K3 S-meter, with ANT 2,
 AUX RF and RX ANT IN terminated in 50 Ohms.

 http://elecraft.365791.n2.nabble.com/file/n7509068/ANT1-2_leakage.jpg

 The isolation between AUX RF and ANT 1/2 is95dB (1-30MHz), rising to -70dB
 (52MHz).
 This was measured with an N2PK VNA.

 I have tried to dress the unscreened wires from ANT 1  2 to the ATU in a
 way to minimise coupling, but the coupling is dominated by the capacitance
 of relays K18  K19.

 Using ANT1/2 for Diversity reception means the receivers are never truly
 independent. There is likely to be more coupling inside the K3 than can
 usually be achieved by physical separation of the antennas.

 Operating Diversity reception with the SUB RX fed from the AUX RF BNC input
 is the way to go.

 73 Mark G4AXX
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Re: [Elecraft] K3 ANT 1-2 isolation

2012-04-29 Thread Guy Olinger K2AV
You are getting some really worse numbers than I did.

You may have ant2 only terminated on one end of its cable connections,
which would be really worse on 6 meters than 160.  There is one of those
bitty jacks that needs a cable attached to it and then terminated.  It's
the other antenna connection that allows you to listen on whichever of
ANT1/2 the TX is NOT using.

Out on Core Banks, NC, we were using doublets at right angles on the same
pole to ANT1 and ANT2, receiving with diversity.  There was 30 dB
separation with the two antennas hanging on the same pole.  How much better
does it have to be inside the K3?

You need to terminate the internal K3 connection of ANT2 when you make the
measurement.  Also the shields of both cable connections at both ends need
to be grounded as well as terminated.

73, Guy.

On Sun, Apr 29, 2012 at 9:28 AM, Mike Harris mike.har...@cwimail.fk wrote:

 Interesting.  I looked at it from the other direction.  With the K3 ANT1
 connected to a dummy load and ANT2 connected also to a dummy load via my
 WM-2 QRP wattmeter.

 With 100W out at ANT1, out of ANT2 I measured 30mW at 50MHz down to 1mW
 at 7.1MHz.  A range of -30dB to -50dB.  50MHz is not in the WM-2 spec,
 however, 25mW was measured at 28.2MHz which gives -36dB.

 There are obviously potential measurement errors there so no one needs
 to take it as absolute. Perhaps someone with access to precision
 equipment could also do the test.

 Regards,

 Mike VP8NO



 On 28/04/2012 12:27, Mark - G4AXX wrote:
  The isolation between ANT 1 and ANT 2 varies from -76dB at 1.8MHz to
 -46dB at
  50MHz.
  This is measured with a signal generator, using the K3 S-meter, with ANT
 2,
  AUX RF and RX ANT IN terminated in 50 Ohms.
 
  http://elecraft.365791.n2.nabble.com/file/n7509068/ANT1-2_leakage.jpg
 
  The isolation between AUX RF and ANT 1/2 is95dB (1-30MHz), rising to
 -70dB
  (52MHz).
  This was measured with an N2PK VNA.
 
  I have tried to dress the unscreened wires from ANT 1  2 to the ATU in a
  way to minimise coupling, but the coupling is dominated by the
 capacitance
  of relays K18  K19.
 
  Using ANT1/2 for Diversity reception means the receivers are never truly
  independent. There is likely to be more coupling inside the K3 than can
  usually be achieved by physical separation of the antennas.
 
  Operating Diversity reception with the SUB RX fed from the AUX RF BNC
 input
  is the way to go.
 
  73 Mark G4AXX
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Re: [Elecraft] K3 ANT 1-2 isolation

2012-04-29 Thread Mike Harris
I thought it was clear that all I was looking at was a transmit 
parameter, that is, what came out of ANT2 when ANT1 was was carrying a 
signal.  This gives an idea of the coupling across the C/O relay K18 
which selects ANT1 or 2.  In this context both ports were terminated.

I fail to see why I should also have to terminate J43 on the KAT3, it 
would in effect doubly terminate the port with one termination before 
the wattmeter and one after.  Not a satisfactory situation for the 
measurement.  Naturally, if the Sub RX is connected to J43 that job 
would be being done by the input of the RX and readings might be different.

I have my Sub RX either listening to the same antenna as the Main RX or 
to the Aux antenna port.  Nothing connected to J43.

The idea was to see what happens with one of a set of standard set-ups, 
not one where the configuration has been rigged to try and maximise a 
reading. If there is a real need to absolutely minimise what came out 
of, or into, the unused antenna port then by all means terminate J43. 
It's yours to do with what you like.

Regards,

Mike VP8NO

On 29/04/2012 17:06, Guy Olinger K2AV wrote:
 You are getting some really worse numbers than I did.

 You may have ant2 only terminated on one end of its cable connections,
 which would be really worse on 6 meters than 160.  There is one of those
 bitty jacks that needs a cable attached to it and then terminated.  It's
 the other antenna connection that allows you to listen on whichever of
 ANT1/2 the TX is NOT using.

 Out on Core Banks, NC, we were using doublets at right angles on the same
 pole to ANT1 and ANT2, receiving with diversity.  There was 30 dB
 separation with the two antennas hanging on the same pole.  How much better
 does it have to be inside the K3?

 You need to terminate the internal K3 connection of ANT2 when you make the
 measurement.  Also the shields of both cable connections at both ends need
 to be grounded as well as terminated.

 73, Guy.

 On Sun, Apr 29, 2012 at 9:28 AM, Mike Harrismike.har...@cwimail.fk  wrote:

 Interesting.  I looked at it from the other direction.  With the K3 ANT1
 connected to a dummy load and ANT2 connected also to a dummy load via my
 WM-2 QRP wattmeter.

 With 100W out at ANT1, out of ANT2 I measured 30mW at 50MHz down to 1mW
 at 7.1MHz.  A range of -30dB to -50dB.  50MHz is not in the WM-2 spec,
 however, 25mW was measured at 28.2MHz which gives -36dB.

 There are obviously potential measurement errors there so no one needs
 to take it as absolute. Perhaps someone with access to precision
 equipment could also do the test.

 Regards,

 Mike VP8NO



 On 28/04/2012 12:27, Mark - G4AXX wrote:
 The isolation between ANT 1 and ANT 2 varies from -76dB at 1.8MHz to
 -46dB at
 50MHz.
 This is measured with a signal generator, using the K3 S-meter, with ANT
 2,
 AUX RF and RX ANT IN terminated in 50 Ohms.

 http://elecraft.365791.n2.nabble.com/file/n7509068/ANT1-2_leakage.jpg

 The isolation between AUX RF and ANT 1/2 is95dB (1-30MHz), rising to
 -70dB
 (52MHz).
 This was measured with an N2PK VNA.

 I have tried to dress the unscreened wires from ANT 1   2 to the ATU in a
 way to minimise coupling, but the coupling is dominated by the
 capacitance
 of relays K18   K19.

 Using ANT1/2 for Diversity reception means the receivers are never truly
 independent. There is likely to be more coupling inside the K3 than can
 usually be achieved by physical separation of the antennas.

 Operating Diversity reception with the SUB RX fed from the AUX RF BNC
 input
 is the way to go.

 73 Mark G4AXX
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Re: [Elecraft] K3 ANT 1-2 isolation

2012-04-29 Thread Guy Olinger K2AV
In your context the ANT1 circuit was normally terminated, one port in the
transmitter, the other in an antenna. That's normal, a load on both ends.
ANT2 was NOT normally terminated unless you want to treat the reactive 10
k+ Z termination of the tiny capacitance across the relay as normal.

If antenna two was actually being used for something while TX on ANT2,
there would be something on J43 when not in transmit. If you have a sub RX
on the non-TX line, then the crossover means something, as in do I need to
close the COR relay.  But that now is the same as your ANT1 termination, TX
on one end, ANTenna on the other, except RX on one end and antenna on the
other.

I could say that your method was the one rigged (as in not normal), and was
devised to come up with the worst possible reading.  I actually USE ANT 2
during TX on ANT 1.  That's when you want to know the separation.  I don't
get readings as bad as yours.

73, Guy.


On Sun, Apr 29, 2012 at 5:51 PM, Mike Harris mike.har...@cwimail.fk wrote:

 I thought it was clear that all I was looking at was a transmit
 parameter, that is, what came out of ANT2 when ANT1 was was carrying a
 signal.  This gives an idea of the coupling across the C/O relay K18
 which selects ANT1 or 2.  In this context both ports were terminated.

 I fail to see why I should also have to terminate J43 on the KAT3, it
 would in effect doubly terminate the port with one termination before
 the wattmeter and one after.  Not a satisfactory situation for the
 measurement.  Naturally, if the Sub RX is connected to J43 that job
 would be being done by the input of the RX and readings might be different.

 I have my Sub RX either listening to the same antenna as the Main RX or
 to the Aux antenna port.  Nothing connected to J43.

 The idea was to see what happens with one of a set of standard set-ups,
 not one where the configuration has been rigged to try and maximise a
 reading. If there is a real need to absolutely minimise what came out
 of, or into, the unused antenna port then by all means terminate J43.
 It's yours to do with what you like.

 Regards,

 Mike VP8NO

 On 29/04/2012 17:06, Guy Olinger K2AV wrote:
  You are getting some really worse numbers than I did.
 
  You may have ant2 only terminated on one end of its cable connections,
  which would be really worse on 6 meters than 160.  There is one of those
  bitty jacks that needs a cable attached to it and then terminated.  It's
  the other antenna connection that allows you to listen on whichever of
  ANT1/2 the TX is NOT using.
 
  Out on Core Banks, NC, we were using doublets at right angles on the same
  pole to ANT1 and ANT2, receiving with diversity.  There was 30 dB
  separation with the two antennas hanging on the same pole.  How much
 better
  does it have to be inside the K3?
 
  You need to terminate the internal K3 connection of ANT2 when you make
 the
  measurement.  Also the shields of both cable connections at both ends
 need
  to be grounded as well as terminated.
 
  73, Guy.
 
  On Sun, Apr 29, 2012 at 9:28 AM, Mike Harrismike.har...@cwimail.fk
  wrote:
 
  Interesting.  I looked at it from the other direction.  With the K3 ANT1
  connected to a dummy load and ANT2 connected also to a dummy load via my
  WM-2 QRP wattmeter.
 
  With 100W out at ANT1, out of ANT2 I measured 30mW at 50MHz down to 1mW
  at 7.1MHz.  A range of -30dB to -50dB.  50MHz is not in the WM-2 spec,
  however, 25mW was measured at 28.2MHz which gives -36dB.
 
  There are obviously potential measurement errors there so no one needs
  to take it as absolute. Perhaps someone with access to precision
  equipment could also do the test.
 
  Regards,
 
  Mike VP8NO
 
 
 
  On 28/04/2012 12:27, Mark - G4AXX wrote:
  The isolation between ANT 1 and ANT 2 varies from -76dB at 1.8MHz to
  -46dB at
  50MHz.
  This is measured with a signal generator, using the K3 S-meter, with
 ANT
  2,
  AUX RF and RX ANT IN terminated in 50 Ohms.
 
  http://elecraft.365791.n2.nabble.com/file/n7509068/ANT1-2_leakage.jpg
 
  The isolation between AUX RF and ANT 1/2 is95dB (1-30MHz), rising to
  -70dB
  (52MHz).
  This was measured with an N2PK VNA.
 
  I have tried to dress the unscreened wires from ANT 1   2 to the ATU
 in a
  way to minimise coupling, but the coupling is dominated by the
  capacitance
  of relays K18   K19.
 
  Using ANT1/2 for Diversity reception means the receivers are never
 truly
  independent. There is likely to be more coupling inside the K3 than can
  usually be achieved by physical separation of the antennas.
 
  Operating Diversity reception with the SUB RX fed from the AUX RF BNC
  input
  is the way to go.
 
  73 Mark G4AXX
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Re: [Elecraft] K3 ANT 1-2 isolation

2012-04-29 Thread Mike Harris
So what you are essentially saying is the K3 has a design fault because 
in a perfectly normal factory configuration it is leaving a port 
unterminated.  Maybe it is the electronic equivalent of a Persian rug.

I'm not rigging anything, it's how it is right out of the box.

I think the real objection here is simply that a low number is reported 
which is contrary to the perceived wish for the K3 to be somehow perfect.

Regards,

Mike VP8NO

On 29/04/2012 21:47, Guy Olinger K2AV wrote:
 In your context the ANT1 circuit was normally terminated, one port in the
 transmitter, the other in an antenna. That's normal, a load on both ends.
 ANT2 was NOT normally terminated unless you want to treat the reactive 10
 k+ Z termination of the tiny capacitance across the relay as normal.

 If antenna two was actually being used for something while TX on ANT2,
 there would be something on J43 when not in transmit. If you have a sub RX
 on the non-TX line, then the crossover means something, as in do I need to
 close the COR relay.  But that now is the same as your ANT1 termination, TX
 on one end, ANTenna on the other, except RX on one end and antenna on the
 other.

 I could say that your method was the one rigged (as in not normal), and was
 devised to come up with the worst possible reading.  I actually USE ANT 2
 during TX on ANT 1.  That's when you want to know the separation.  I don't
 get readings as bad as yours.

 73, Guy.


 On Sun, Apr 29, 2012 at 5:51 PM, Mike Harrismike.har...@cwimail.fk  wrote:

 I thought it was clear that all I was looking at was a transmit
 parameter, that is, what came out of ANT2 when ANT1 was was carrying a
 signal.  This gives an idea of the coupling across the C/O relay K18
 which selects ANT1 or 2.  In this context both ports were terminated.

 I fail to see why I should also have to terminate J43 on the KAT3, it
 would in effect doubly terminate the port with one termination before
 the wattmeter and one after.  Not a satisfactory situation for the
 measurement.  Naturally, if the Sub RX is connected to J43 that job
 would be being done by the input of the RX and readings might be different.

 I have my Sub RX either listening to the same antenna as the Main RX or
 to the Aux antenna port.  Nothing connected to J43.

 The idea was to see what happens with one of a set of standard set-ups,
 not one where the configuration has been rigged to try and maximise a
 reading. If there is a real need to absolutely minimise what came out
 of, or into, the unused antenna port then by all means terminate J43.
 It's yours to do with what you like.

 Regards,

 Mike VP8NO

 On 29/04/2012 17:06, Guy Olinger K2AV wrote:
 You are getting some really worse numbers than I did.

 You may have ant2 only terminated on one end of its cable connections,
 which would be really worse on 6 meters than 160.  There is one of those
 bitty jacks that needs a cable attached to it and then terminated.  It's
 the other antenna connection that allows you to listen on whichever of
 ANT1/2 the TX is NOT using.

 Out on Core Banks, NC, we were using doublets at right angles on the same
 pole to ANT1 and ANT2, receiving with diversity.  There was 30 dB
 separation with the two antennas hanging on the same pole.  How much
 better
 does it have to be inside the K3?

 You need to terminate the internal K3 connection of ANT2 when you make
 the
 measurement.  Also the shields of both cable connections at both ends
 need
 to be grounded as well as terminated.

 73, Guy.

 On Sun, Apr 29, 2012 at 9:28 AM, Mike Harrismike.har...@cwimail.fk
   wrote:

 Interesting.  I looked at it from the other direction.  With the K3 ANT1
 connected to a dummy load and ANT2 connected also to a dummy load via my
 WM-2 QRP wattmeter.

 With 100W out at ANT1, out of ANT2 I measured 30mW at 50MHz down to 1mW
 at 7.1MHz.  A range of -30dB to -50dB.  50MHz is not in the WM-2 spec,
 however, 25mW was measured at 28.2MHz which gives -36dB.

 There are obviously potential measurement errors there so no one needs
 to take it as absolute. Perhaps someone with access to precision
 equipment could also do the test.

 Regards,

 Mike VP8NO



 On 28/04/2012 12:27, Mark - G4AXX wrote:
 The isolation between ANT 1 and ANT 2 varies from -76dB at 1.8MHz to
 -46dB at
 50MHz.
 This is measured with a signal generator, using the K3 S-meter, with
 ANT
 2,
 AUX RF and RX ANT IN terminated in 50 Ohms.

 http://elecraft.365791.n2.nabble.com/file/n7509068/ANT1-2_leakage.jpg

 The isolation between AUX RF and ANT 1/2 is95dB (1-30MHz), rising to
 -70dB
 (52MHz).
 This was measured with an N2PK VNA.

 I have tried to dress the unscreened wires from ANT 12 to the ATU
 in a
 way to minimise coupling, but the coupling is dominated by the
 capacitance
 of relays K18K19.

 Using ANT1/2 for Diversity reception means the receivers are never
 truly
 independent. There is likely to be more coupling inside the K3 than can
 usually be achieved by physical separation of the 

Re: [Elecraft] K3 ANT 1-2 isolation

2012-04-28 Thread Mark - G4AXX
The isolation between ANT 1 and ANT 2 varies from -76dB at 1.8MHz to -46dB at
50MHz. 
This is measured with a signal generator, using the K3 S-meter, with ANT 2,
AUX RF and RX ANT IN terminated in 50 Ohms.

http://elecraft.365791.n2.nabble.com/file/n7509068/ANT1-2_leakage.jpg 

The isolation between AUX RF and ANT 1/2 is 95dB (1-30MHz), rising to -70dB
(52MHz). 
This was measured with an N2PK VNA.

I have tried to dress the unscreened wires from ANT 1  2 to the ATU in a
way to minimise coupling, but the coupling is dominated by the capacitance
of relays K18  K19.  

Using ANT1/2 for Diversity reception means the receivers are never truly
independent. There is likely to be more coupling inside the K3 than can
usually be achieved by physical separation of the antennas.

Operating Diversity reception with the SUB RX fed from the AUX RF BNC input
is the way to go.

73 Mark G4AXX


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Re: [Elecraft] K3 ANT 1-2 isolation

2012-04-28 Thread Mark n2qt
with isolation numbers like this perhaps there is hope for
duplex mode, with transmitting on one band with the
subrx enabled and listening on another??

Hopefully!

Mark n2qt


-Original Message- 
From: Mark - G4AXX
Sent: Saturday, April 28, 2012 11:27 AM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] K3 ANT 1-2 isolation

The isolation between ANT 1 and ANT 2 varies from -76dB at 1.8MHz to -46dB 
at
50MHz.
This is measured with a signal generator, using the K3 S-meter, with ANT 2,
AUX RF and RX ANT IN terminated in 50 Ohms.

http://elecraft.365791.n2.nabble.com/file/n7509068/ANT1-2_leakage.jpg

The isolation between AUX RF and ANT 1/2 is 95dB (1-30MHz), rising to -70dB
(52MHz).
This was measured with an N2PK VNA.

I have tried to dress the unscreened wires from ANT 1  2 to the ATU in a
way to minimise coupling, but the coupling is dominated by the capacitance
of relays K18  K19.

Using ANT1/2 for Diversity reception means the receivers are never truly
independent. There is likely to be more coupling inside the K3 than can
usually be achieved by physical separation of the antennas.

Operating Diversity reception with the SUB RX fed from the AUX RF BNC input
is the way to go.

73 Mark G4AXX


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Re: [Elecraft] K3 ANT 1-2 isolation

2012-04-26 Thread Ignacy
True that the isolation between ATN1, ANT2 and RX Ant are poor. The solution
is to use a preamp in receive antennas so that signals from RX and TX
antennas are similar in strength.
Ignacy



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Re: [Elecraft] K3 ANT 1-2 isolation

2012-04-26 Thread Mike Harris
Poor is a bit harsh, what do you expect from a single small C/O relay. 
Anything over 30dB isolation is a luxury.

Regards,

Mike VP8NO

On 26/04/2012 11:24, Ignacy wrote:
 True that the isolation between ATN1, ANT2 and RX Ant are poor. The solution
 is to use a preamp in receive antennas so that signals from RX and TX
 antennas are similar in strength.
 Ignacy
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Re: [Elecraft] K3 ANT 1-2 isolation

2012-04-26 Thread Matt Zilmer
Might be considered poor in relation to coaxial switches.  Some of
these get  70 dB isolation.

73,
matt W6NIA

On Thu, 26 Apr 2012 15:44:39 -0300, you wrote:

Poor is a bit harsh, what do you expect from a single small C/O relay. 
Anything over 30dB isolation is a luxury.

Regards,

Mike VP8NO

On 26/04/2012 11:24, Ignacy wrote:
 True that the isolation between ATN1, ANT2 and RX Ant are poor. The solution
 is to use a preamp in receive antennas so that signals from RX and TX
 antennas are similar in strength.
 Ignacy
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Re: [Elecraft] K3 ANT 1-2 isolation

2012-04-26 Thread Guy Olinger K2AV
I have much greater separations than 30 dB when the jacks are terminated
with real lines, so I'll have to assume that readings like 30 dB are
listening in an unterminated port with signals on another.  You can't
measure separation (or RX noise) without line terminations (resistor or
real antenna) on ALL ports.

73, Guy.

On Thu, Apr 26, 2012 at 3:17 PM, Matt Zilmer mzil...@verizon.net wrote:

 Might be considered poor in relation to coaxial switches.  Some of
 these get  70 dB isolation.

 73,
 matt W6NIA

 On Thu, 26 Apr 2012 15:44:39 -0300, you wrote:

 Poor is a bit harsh, what do you expect from a single small C/O relay.
 Anything over 30dB isolation is a luxury.
 
 Regards,
 
 Mike VP8NO
 
 On 26/04/2012 11:24, Ignacy wrote:
  True that the isolation between ATN1, ANT2 and RX Ant are poor. The
 solution
  is to use a preamp in receive antennas so that signals from RX and TX
  antennas are similar in strength.
  Ignacy
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