KX1 : poor sensitivity on 30/20 m with KBX3080

[luc Favre-2]

Good morning,
I installed the KBX3080 module and all seems to run OK. Tx power juste fine
on all bands. Great sensivity on 40/80 (0.2 µV), but poor sensivity on 30
and 20 (0.8 and 1.0 µV).
Transmit low pass filter is OK.
KBX3080 module tensions (versus freq.) are OK too and adj. condenser are
right installed.
I tried to inject RF along the RX chain : at point A still poor sensitivity,
at pot R1 side L6 end, full sensivity (0.2 µB or even better). I then
changed L6, still poor sensitivity. The problem seems to be in the module
itself, but no idea where.
Any help and/or idea welcome !

73
Luc/F6HJO/HB9ABB


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[Don Wilhelm-4]

Luc,

Temporarily remove the wires that go to points 'A' and 'B' and try again
to peak 20 meters (80 and 30 meters will not work with those wires removed).
If 20 meters has good selectivity with the wires removed, then you can
conclude that the 8030 module has a problem.
OTOH, if 20 meters is still bad, then there is a problem in the low pass
filter area.  Check that K2 is not 'stuck'  One end of capacitors C48
and C49 should be grounded on 40 meters, but not grounded on 20.
Usually a problem with the low pass filter will show up with transmit.
Do check the transmit power levels again.

73,
Don W3FPR

Luc Favre wrote:

> Good morning,
> I installed the KBX3080 module and all seems to run OK. Tx power juste fine
> on all bands. Great sensivity on 40/80 (0.2 µV), but poor sensivity on 30
> and 20 (0.8 and 1.0 µV).
> Transmit low pass filter is OK.
> KBX3080 module tensions (versus freq.) are OK too and adj. condenser are
> right installed.
> I tried to inject RF along the RX chain : at point A still poor sensitivity,
> at pot R1 side L6 end, full sensivity (0.2 µB or even better). I then
> changed L6, still poor sensitivity. The problem seems to be in the module
> itself, but no idea where.
> Any help and/or idea welcome !
>
> 73
> Luc/F6HJO/HB9ABB

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[C. GONDARD-2]

please ignore : just testing a new adress ..
73 de Chris / F6FTB
>
>
>  

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[C. GONDARD-2]

please ignore : just testing a new adress
73 de Chris / F6FTB

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[pa0wit]

Hi Luc,

I have had the same problem due to lightning in the vicinity.
After replacing the SMD diodes on the 30-80 board everything worked nice again.

73 de John pa0wit

luc Favre-2 wrote

Good morning,
I installed the KBX3080 module and all seems to run OK. Tx power juste fine
on all bands. Great sensivity on 40/80 (0.2 µV), but poor sensivity on 30
and 20 (0.8 and 1.0 µV).
Transmit low pass filter is OK.
KBX3080 module tensions (versus freq.) are OK too and adj. condenser are
right installed.
I tried to inject RF along the RX chain : at point A still poor sensitivity,
at pot R1 side L6 end, full sensivity (0.2 µB or even better). I then
changed L6, still poor sensitivity. The problem seems to be in the module
itself, but no idea where.
Any help and/or idea welcome !

73
Luc/F6HJO/HB9ABB


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