80 Transmit on KX1

[Bill Trettin]

I installed the KXB3080 option in my KX1 a couple months ago and everything
checked out OK after completion, including output on 80 meters.  

 

Now however, I am getting no output at all on 80 meters.   I am still
getting 5 volts output at point F, and current draw of the KX1 increases by
around 15ma when I select 80 meters, so it looks like the K1 relay is
switching as it should.

 

I get the same symptoms whether the KXAT1 ATU is installed or removed and
replaced with a jumper.

 

I put a signal generator at the antenna connector and can trace a signal
through the RF section in any of the band positions but in 80 meters, I get
no signal at all, even at the J7 jumper.

 

I'm thinking when I switch to 80 meters and the K1 relay switches, it's
introducing a short somewhere on the KXB3080 board or possibly on the LPF1
board but I haven't been able to find it.  Has anyone else had this problem
or have any ideas?

 

Bill, KF8GE/HL9TY

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[Don Wilhelm-4]

Bill,

My bet would be on a poorly tinned toroid lead either on L1 or L2 on the
LPF board.
The red winding is only used on 80 meters, and the relay shorts out the
red winding on the other bands.
Look very carefully at the back of the LPF board - if you see any trace
of red enamel, that is the problem.

Another check is to see if you have continuity between the BNC jack
center and where the green wire of L1 connects to the board.  You will
have to check with power on and the KX1 set to 80 meters since the relay
on the LPF board is not a latching type.

73,
Don W3FPR

Bill Trettin wrote:

> I installed the KXB3080 option in my KX1 a couple months ago and everything
> checked out OK after completion, including output on 80 meters.  
>
>  
>
> Now however, I am getting no output at all on 80 meters.   I am still
> getting 5 volts output at point F, and current draw of the KX1 increases by
> around 15ma when I select 80 meters, so it looks like the K1 relay is
> switching as it should.
>
>  
>
> I get the same symptoms whether the KXAT1 ATU is installed or removed and
> replaced with a jumper.
>
>  
>
> I put a signal generator at the antenna connector and can trace a signal
> through the RF section in any of the band positions but in 80 meters, I get
> no signal at all, even at the J7 jumper.
>
>  
>
> I'm thinking when I switch to 80 meters and the K1 relay switches, it's
> introducing a short somewhere on the KXB3080 board or possibly on the LPF1
> board but I haven't been able to find it.  Has anyone else had this problem
> or have any ideas?
>
>  
>
> Bill, KF8GE/HL9TY
>
> ______________________________________________________________
> 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
>
>  

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Please help support this email list: http://www.qsl.net/donate.html