[Elecraft] XV transverter switching

[Robert Friess]

Hi Ken,

When a transverter is "deselected" the power is turned off to the RF
circuits in the transverter.  We will provide an option to leave the power
on the LO, but the conversion and gain circuits will be off for sure.  I
think that this should address your concern.

73,
Bob, N6CM


----- Original Message -----
From: "Kenneth E. Harker" <kharker@cs.utexas.edu>
To: "Elecraft Reflector" <elecraft@mailman.qth.net>
Sent: Tuesday, August 12, 2003 7:46 AM
Subject: [Elecraft] XV transverter switching


>      Let me rephrase my questions/concern.
>
>      Let's say it's the ARRL June VHF QSO Party, and I have the XV50 and
XV144
> transverters in a daisy chain configuration with the K2/100 as an IF rig.
> Six meters is wide open and there are signals from 50.100 MHz through
50.250
> MHz.  There's a very loud station running on 50.200 MHz.  I am switching
> back and forth between 144.200 MHz and various frequencies in the six
meter
> band.
>
>      The XV transverters have relays that disconnect the IF ports when you
> deselect that transverter (using the K2/100 as an IF rig.)  So, in the
> daisy chain setup, you are relying on this relay as isolation to keep the
> downconverted signals of the deselected transverters out of the IF.  So
the
> limit of this isolation is the limit of the 28 MHz isolation figure for
> this relay.
>
>      The relay is an Omron G6E-134P - Omron does not seem to publish the
> isolation ratings for this relay.  My guess is that it might not be enough
> for strong signals.  For instance, when listening to 144.200 MHz (28.200
MHz
> IF frequency,) a really strong signal on 50.200 MHz (also 28.200 MHz IF
> frequency) will probably bleed through.  Let's say the transverters are
able
> to produce downconverted IF signals of +0dbm.  The Elecraft K2/100 can
hear
> down to at least -130dbm.  So, doesn't this mean that the relay would need
> a 28 MHz isolation figure in excess of 130db to avoid having strong
signals on
> one band bleed through and sound like weak signals on another band?
>
>      I can't imagine that these relays have that sort of isolation.
>
>
>      Downeast Microwave transverters have the ability to turn their
> downconverter sections completely, while leaving the local oscillator on
> (so as not to cause frequency drift) when you use appropriate external
> switching.  We've had to use this feature at the W5KFT and K5TR contest
> stations, where we often share a single IF rig for the 222 MHz and 432
> MHz transverters.  Is this something that the Elecraft transverters can
> be made to do as well (hopefully automatically with the band-switching
> controlled by AuxBus?)
>
> --
> --------------------------------------------------------------------------
--
> Kenneth E. Harker      "Vox Clamantis in Deserto"
kharker@cs.utexas.edu
> University of Texas at Austin                   Amateur Radio Callsign:
WM5R
> Department of the Computer Sciences          Central Texas DX & Contest
Club
> Taylor Hall TAY 2.124                         Maintainer of Linux on
Laptops
> Austin, TX 78712-1188 USA
http://www.cs.utexas.edu/users/kharker/
> --------------------------------------------------------------------------
--
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