RadioBanter - View Single Post

April 24th 06, 03:12 PM posted to rec.radio.amateur.homebrew

wrote:
hello,

In my receiver project I have reached to point where I need to test my
IF amplifier.
It's based on one MC1350P stage.

I know it should give me approx 60dB gain. First idea that comes to my
mind is that I should feed it with very weak signal. Am I correct: if
feed it with lets say..1 microvolt, then 60dB of gain should give me 1
millivolt at the output?

If so..then how can I get such a low level signal (my Hartley
oscillator gives my 1.7 volts PTP).

Any comments?

A metal box with good coax connectors on both ends, containing a
resistive divider made with _good_ noninductive resistors, is the
first thing that comes to mind. You'll also want _good_ coax cable
(better than 99% shield coverage) on the jumpers from your Hartley
oscillator to the divider box, and from the divider to your amplifier.

It probably would be a _very_ good thing to put your oscillator
inside a shielded metal box, too, with precautions to minimize signal
leakage from the cables and from inside the box. Otherwise you'll be
getting some unmeasured leakage signal into your IF amp as well as the
signal from the output side of the resistive divider, and that will
invalidate your measurements.

Good luck, and let us know how you decide to do this.

--
Mike Andrews, W5EGO

Tired old sysadmin