Transverter Question

[W1JHR]

I have a K2 and added the Elecraft transverter interface using split rx/tx.  
I am using 28 MHZ as an If and use only TRansverter 1 on the menu. I am using  
50/144/222/432 DEM transverters  with split lines out using an external  
switch. The K2 drives the transverters fine but on RX I can hear strong 144 MHZ  
signals even thought I am on 222. For switching I built a DEM IF switch(no  
longer sold). It uses a switch and an IF amp on TX &RX plus pots to balance  out
the power/gain. At first I thought the problem was in the DEM switching box  
because of the IF amplification and the use of a switch as opposed to a relay.  
I  Then built up a switching box using good isolation relays made by Dow  Key
microwave. (2) SP4T are used and controlled by a 2P4T switch which also  
switches the contoll/PTT line but the problem still exists. Has anyone else  
experienced this problem while using the Elecraft transverter interface?
George, W1JHR
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[Don Wilhelm-3]

George,

Since you are hearing 144 MHz signals, I would think you should investigate
either the transverter interface hookup or address the problem with DEM -
the K2 is set to receive 28 MHz signals, and if you hear 144 MHz, it has to
be coming from one of the DEM transverters - does your switch de-activate
the unused transverters or does it simply disconnect the output coax?  If
the transverter is still active, I can understand that you may have some
strange feedthrough path that exists - the ground connections are a common
suspect in similar cases, and the use of a common power supply for the
transverters may also provide a 'sneak' path.

We can only guess at the cause, but I have trouble believing that the K2
transverter interface is causing it since it only receives 28 MHz. signals,
and something in your arrangement is causing the 144 MHz signals to be
converted to 28 MHz.

73,
Don W3FPR

> -----Original Message-----
>
> I have a K2 and added the Elecraft transverter interface using
> split rx/tx.
> I am using 28 MHZ as an If and use only TRansverter 1 on the
> menu. I am using
> 50/144/222/432 DEM transverters  with split lines out using an external
> switch. The K2 drives the transverters fine but on RX I can hear
> strong 144 MHZ
> signals even thought I am on 222. For switching I built a DEM IF
> switch(no
> longer sold). It uses a switch and an IF amp on TX &RX plus pots
> to balance  out
> the power/gain. At first I thought the problem was in the DEM
> switching box
> because of the IF amplification and the use of a switch as
> opposed to a relay.
> I  Then built up a switching box using good isolation relays made
> by Dow  Key
> microwave. (2) SP4T are used and controlled by a 2P4T switch which also
> switches the contoll/PTT line but the problem still exists. Has
> anyone else
> experienced this problem while using the Elecraft transverter interface?
> George, W1JHR
>

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