Steve,
TX Buffer U9 is a rail-to-rail op amp, and the maximum signal output
swing will depend on the supply voltage.
So, if you are operating from a supply voltage lower than 13.8 volts,
the maximum power from the K60XV may be limited. I would suggest you
modify the TRN menus for a maximum of something like 0.75 mW and adjust
the input attenuator on the transverters (assuming the Elecraft XV
series transverters) to work with that lower level.
The reason for changing the TRN menus is to keep from overdriving the
transverters when operating from a higher voltage power source.
73,
Don W3FPR
On 6/18/2014 10:03 AM, Steve Kavanagh wrote:
I noticed this past weekend that my K2's transverter output level was lower
than the nominal 1 mW it was set to when operating from the car battery with
the ignition off. I confirmed this behaviour today, with about a 12.2 V power
supply voltage to the K2. The power control of the K60XV worked fine up to
about 0.85 mW but was unable to go higher when the power knob was turned up to
maximum. There's no problem when running from a 14 V supply.
The only transmitter stage running from the unregulated 12 V rail (in transverter mode) seems to be the buffer U9 - does anyone know if this stage is running close to its compression point and if this behaviour is normal ? Its gain appears to be fixed by resistors and one capacitor and shouldn't be very voltage-dependent. Or do I need to look into tweaking the 10-12 m bandpass filter to get a bit more margin ? Or maybe adjust/modify my transverters to run from a lower input level ?
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