[Andrew2]

Back again.

Here's the block diagram of the phaser. A few notes might help:

The two DC injectors will only be required if you are using active (powered) aerials. Wire aerials can go straight to the next stage.

The level pot for the main path should be low value, say 100 to 500 ohms.

The resistive combiner is simply two resistors commoned at the OUT socket. Low values such as 50 or 100 ohms should be OK. This will lose a little signal but I don't find it to be a problem.

In the noise path, L1, L2, and L3 are chosen to resonate with the variable capacitor on the required bands. Iused small axial inductors from the junk box. Values in the range 20 to 150uH rings a bell, and bigger if you want to go down to LW. I *think* I had to add a couple of hundred pf across the noise antenna input when using a wire aerial to make the tuning behave.

The dual gate fet in mine is the old-but-good 40673. G2 is fixed biased to a couple of volts and I think the source r is a couple of hundred ohms with the drain r at 1k or so. Worth a fiddle with.

Phase splitter is standard stuff with 1k in emitter and collector. Set base bias to get a couple of volts across each.

As the level pot feeds the emitter follower, a value of a few k is OK.

Emitter follower load is a few hundred ohms.

Apart from the 12v for the active antennas, the whole thing runs from an 8v regulator.

**Just remembered I added on/off switches to enable the quick selection of one or both channels. A good place for them is after each level pot.**


If you haven't used a phaser-outer before, be prepared for some frustration as the null can be shallow and difficult to find at first.
First of all, check that both channels are working. The main channel is broadband so your receiver should work as normal via this channel.
The noise channel is tuned, so it should be possible to hit a peak on any chosen frequency in the design range. Bear in mind I have never tried this cct above 4 MHz - I suspect the noise channel will have a falling response as the frequency rises.

Once you know it's all working, tune your radio to a moderately strong MW broadcast and using only the noise channel, make sure you can peak it. If your receiver has a signal level indicator, note the strength at peak.

Switch over to the main channel only and adjust the main level pot for the same strength. Level-matching to within a few dB is important for the best null.

With both channels on, flip the reversal switch and use the setting that gives *minimum* signal. The null may be only small at this stage.

Carefully adjust the tuning cap for a dip in strength. Re-adjust the noise level pot for a better null. Repeat these two adjustments until the null is sharp and deep.

It's the same procedure when nulling noise, but it's worth checking that both antennas are hearing the same kind of noise, because if they aren't the noise won't cancel.

I've also found a few photos of the phaser during construction.