Quote:
Originally Posted by Penthode
The reason for detuning is so that you can clearly see the primary peak. Then you proceed to the discriminator zero adjustment. The "null" does not mean minimum. It means zero. The adjustment will swing plus and minus. You want zero. I normally set the vtvm to read zero mid scale so when I adjust the secondary adjustment I can clearly see it swing positive and negative.
Once the discriminator zero adjustment is made, you generally go back to the primary to slightly touch it up to make the discriminator peaks equal amplitude. Then again confirm the discriminator zero adjustment.
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OK the secondary has been detuned. I know multiple photos are annoying but here is what I have setup to go.
Here is my VTVM. To be honest, reading voltages and resistance is about all I have done with this. Peaking is something I haven't done often. The instructions say a 3 volt scale but all I have in that range is 1.5 volts and 5 volts. It's set for the 1.5 volt range. From your instructions, I'm not concerned with values, just with maximum movement on the needle? I have it zeroed to the bottom scale which is dBm.
Instructions say use a probe in series with a 1 meg resistor. My probe has this resistor built into the probe.
The generator is set for 21.25mc at 100mv. The meter doesn't show this voltage but I confirmed it on my scope.
Here are the input and output to VTVM points. Input is to pin #1 V117 and the DC probe is on the dual resistor (R203 and R204) on terminal C on the secondary.
So I guess I'm asking is does this setup look OK? My biggest concern is am I using the VTVM correctly, arbitrarily zeroed to the midpoint of the scale and tuning the primary for maximum deflection to...what, the left or does it not matter?