K3 Sensitivity problem on 75/80 and 160 meters

[Jan Ditzian]

I have a K3 that works fine on all bands except 75/80 and 160.   I have
a backup rig, an IC-730 from the 1980's, that has 75/80 but not 160.  I
did an A/B with the two rigs on 80 meters, and both the S-meter and my
ears tell me that signals are 5-7 S-units weaker on the the K3.  S/N is
clearly worse on the K3 than on the 730.

Can someone clue me as to how to chase this down?  Even if I have to
send a board back to Elecraft, I would like to do that rather than send
the radio.

Thank you,

Jan, KX2A

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

[Joe Subich, W4TV-4]

 > Can someone clue me as to how to chase this down?

The easiest, most accurate way is to actually measure sensitivity using
an XG-2 or XG-3 signal generator.  You can check the S-meter on 80 and
160 compared to 20 meters and calculate the MDS on each band following
the method in the signal generator manual.

Have you calibrated the RF gain of the rig and checked the antenna
settings (ANT 1/ANT 2 if you have the KAT3 or Main/RX if you have a
KXV3 installed)?  Both antenna settings are saved per band as is the
preamp and attenuator.

73,

   ... Joe, W4TV


On 2015-03-15 8:41 PM, Jan wrote:

> I have a K3 that works fine on all bands except 75/80 and 160.   I have
> a backup rig, an IC-730 from the 1980's, that has 75/80 but not 160.  I
> did an A/B with the two rigs on 80 meters, and both the S-meter and my
> ears tell me that signals are 5-7 S-units weaker on the the K3.  S/N is
> clearly worse on the K3 than on the 730.
>
> Can someone clue me as to how to chase this down?  Even if I have to
> send a board back to Elecraft, I would like to do that rather than send
> the radio.
>
> Thank you,
>
> Jan, KX2A
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

[Don Wilhelm-4]

Jan,

Check your antenna selections - ANT1 vs. ANT2 or RX ANT on vs. off.
The amount of attenuation you hear is about the same as the isolation
between the antenna selection in the K3 (40 to 50 dB).

The antenna selection is on a per band basis.

73,
Don W3FPR

On 3/15/2015 8:41 PM, Jan wrote:
> I have a K3 that works fine on all bands except 75/80 and 160.   I
> have a backup rig, an IC-730 from the 1980's, that has 75/80 but not
> 160.  I did an A/B with the two rigs on 80 meters, and both the
> S-meter and my ears tell me that signals are 5-7 S-units weaker on the
> the K3.  S/N is clearly worse on the K3 than on the 730.
>
> Can someone clue me as to how to chase this down?  Even if I have to
> send a board back to Elecraft, I would like to do that rather than
> send the radio.

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]