Thread: dBm and Voltage
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Old June 7th 05, 06:46 PM
K7ITM
 
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Hi Hern=E1n,

Hope a couple comments will be helpful:

I'd suggest you reconsider using the LTC6903. The data sheet says it
has a lot of jitter, which will translate to huge phase noise... If
you connect up just the LTC6903 and listen to its output on a good
receiver, if it doesn't sound like a clean tone (SSB/CW mode receiver)
or a noisless carrier, that's what it's going to add to whatever signal
you want to listen to when using it as an LO for a receiver. There are
probably some very decent low-power LO designs in the QRP community
that you could adapt. May be difficult to get wideband digital
control, which it looks like you might be trying to get with the LTC
part.

I suppose the AD607 is pretty tolerant of levels at the LO input, and
it's a relatively high input impedance. You don't have to waste power
by adding an external 50 ohm resistor. Get the LO input voltage level
close to the suggested value or a bit more and you should be fine.

Cheers,
Tom

nanchez wrote:
Hi

Thanks to all of you... like Roy said, this newsgroup is very
educational... now I have enough information to make some
experimentation with this mixer and oscillator... actually, the mixer
is an Analog Devices AD607 and the oscillator is a Linear LTC6903...
I'm planning to build my own rig...
=20
Thank you so much.
=20
Hern=E1n S=E1nchez
HJ4SZY